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for the sqfe use of lqsers

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Contents SECTION
l. General
I q^^na
r.r oeuPc.
1.2 Application.
1.3 l,aser Safety Oflicer (LSO)
2. Definitions
3. Hazard Evaluation and Classification
3.1 Ceneral.
3.2 LaserConsiderations.
3.3 Laser and I-aser System Hazard Classification
Definitions.
3.4 Environment in Which the Laser is Used.
3.5 Personnel.
4. Control Measures
4.1 General Considerations. .
4.2 Laser Safety Oflicer (LSO).
4.3 Engineering Controls.
4.4 Administrative and Procedural Controls. . .
4.5 Special Considerations .
4.6 PersonalProtectiveEquipmeni .....
4.7 Waming Signs and Labels
4.8 Service and Repair of Laser Systems. . . . ' ,
4.9 Modification of Laser Systems.
5. Laser Safety and Training Programs
5.1 Organization.
5.2 Education.
5.3 Implementation. .....
Medical Surveillance
6.1 General.
6.2 Personnel Categories-
6.3 General Procedures.
6.4 Frequency of Medical Examinations.
7. SoecialConsiderations
7. t Industrial Hygiene Considerations.
7.2 Explosion Hazards. ....
7.3 Optical Radiation Hazards -
(Other than Laser Beam Hazards).
7.4 Electrical Hazards. .
7.5 Flammability ofLaser Beam Enclosutes. .
7.6 Laser Operation in Outdoor Environments .
Criteria for Exposure of the Eye and Skin
8.1 Intrabeam Viewing and Extended-Source Ocular Exposures. . . .
8.2 MPE for Intrabeam Viewing.
8.3 MPE for Extended-Source Viewing. . . . . .
8.4 MPE for Skin Exnosure to a Laser Beam.
8.5 Special Qualifications - lnfrared.
9. Measurements
9.1 General.
9.2 lntrabeam and Extended-Source Measurements,
9,3 Instruments.
I
I
I
6
6
7
8
9
l0
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l')
t6
tt
t9
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22
z2
22
22
22
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23
23
23
23
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24
25
25
25
25
26
26
27
2'l
27
28

o
SECTION
10. Revision of American National Standards
Refened to in This Document
Tables
Table I Accessible Emission Limits for Selected
Continuous-Wave Lasers and
Laser Systems
Table 2 Summary of Levels (Energy and Radiant
Exposure Emissions) for Single-Pulsed
Leser and Laser System Classification
Table 3 Maximum Radiant Exposure Incident Upon a Diffuse
Surface Which Will Not Produce Hazardous Reflections
Table 4 Minimum Optical Densities Required
forProtectiveEyewear . . ., .
Table 5 MPE for Direct Ocular Exposure, Intrabeam
Viewing, to a LaserBeam ..
Table 6 MPE for Viewing a Diffuse Reflection of a
Laser Beam or an Extended Source
Table7
MPE for Skin Exposurc to a Laser Beam
Table 8 Required Radiomeric Parameters
Table 9 Maximum Apenure Diameters (Limiting Aperture)
for Measurement Averaging
Table l0 Control Measures for the Four Laser Classes
Figurcs
Fig. la
Fig. lb
Fig. lc
Fig. 2a
Fig. 2b
Fig. 2c
Fig. 2d
Fig. 2e
Fig. 3
Fig. 4
Sample Waming Sign for Class 2
and Certain Class 3a Lasers
Sample Waming Sign for Certain Class 3a Lasers and for
Class 3b and Class 4 Lasers
Sample Waming Sign for Temporary
Conholled Area
Area,/EntrYway Safety Controls
for Class 4 Lasen
Safeay Controls for Class 4 Lasers where
Arey'Entryway Controls are Inappropriate . . . .
Unsupervised Laser Installation for
Demonstrationlaser .,,,.
Supervised Laser lnstallation for
Demonshationlaser .... .
Supervised Laser Installation for
Demonstrationlaser ....,
Limiting Angular Subtense (Apparent Visual Angle),
0tn6, for l"= 0.4 to 1.4 lrm
MPE for Direct Ocular Exposure to Visible and Near
Infrared Radiation (1"= 0.4 to 1.4 pm) Intrabeam
Viewing (Angular Subtense < o'n;n in Fig. 3), for
Single Pulses or Exposures .
28
30
3l
3l
JJ
34
35
35
36
4l
43

o
SECTION
Fie. MPE for Direct Ocular Exposure to Ultraviolei
Radiation (Intrabeam Viewing and Extended
Sources) for Exposure Durations from l0e to 3 x ld s
Fig. 6 MPE for Direct Ocular Exposure to Ultraviolet
(1" = 0.315 to 0.400 pm) and Infrarcd
(1, = 1.4 pm to I mm) Radiation (lntrabeam
Viewing aod Extended Sources) for Single
Pulses or Continuous Exposures
Fig. 7 MPE for Direct Ocular Exposure to Laser Radiation
(1" = 0.4 to 0.7 pm and 1.051 to 1.4 pm) from
Extended Sources (Angular Subtense >cln;n in Fig' 3)
for Single Pulses or Continuous ExPosures
Fig. 8 Conection Factor C,a for WaYelengths Between
0.7 and l4 pm (From Tables 5 and 6)
Fig. 9 Correction Factors CB and ft for Wavelengths
Between 0.55 and 0.7 um . .
Fig l0 Ocular MPE for lntrabeam Viewing (Angular
Subtense < cr,n6 in Fig. 3) as a Function
of Exposure Dumtion and Wavelength
Fig. ll Ocular MPE for Extended Sources (Angular
Subtense 2 cr-6, in Fig. 3) as a Function
of Exposure Duration and Wavelength
Fig. 12 Reduction ofMPE for Repetitively Pulsed Lasers and
for Multiple Exposures from Scanning Lasers ' . .
Fig. 13 Measurement Arrangement Used for Purposes
of Laser Classification ....
Appendixes
Appendix A Examples of Classification of Lasers or Laser Systems
Tables
Table Al Typical Laser Classilication - Continuous-Wave (CW) Lasers . . . . .
Table A2 Typical Laser Classification - Single-Pulse Lasers
Table ,A3 lntrabeam MPE for the Eye and Skin for
Selected CW Lasers
Table 44 Inrabeam MPE for the Eye and Skin for
Selected Pulsed Lasers
Appendix B Calculation for Hazard Evaluation and Classification
8.1 General .
8.2
B.3
8.4
Tables
Symbols
Examples of MPE Determinadon and Laser Classification
Formulas and Examples Useful in Evaluation
of Various Laser Applications
Table B I Typical Diffuse Reflection Cases for Visible Radiation
(l=0.4to0.?um) ...
PACE
47
48
49
50
52
)J
J)
)t
)/
58
58
59
59
59
60
tt)

SECTION
Figures
Fig. Bl
Fig. 92
Fig. 83
Fig. 84
Fig. 85
Fig' 86
Fig. B7
Appendix C
Figures
Fig. Cl
Fig. C2
Appendix D
Dl.
D2.
D3.
Dl.
D5.
D6.
D7.
Tables
Table Dl
Intrabeam Viewing - Direct (himary) Beam
lntrabeam Viewing - Specularly Reflected (Secondary) Beam " " ' '
Extended-Source Viewing - Normally Diffuse Reflection
Examples of Use of l-aser Range Equation for
Determining Nominal Hazard Distance
Nominal Hazard Zone for Diffuse Reflection
Laser Range F4uation Nomogram ' ' ' '
Diagram of the l-aser Arrangement for Exampte 26
lnformation and References for Sections 3 and 4
IEC-825 (1985) Waming Label -
Hazard Symbol
IEC-825 (1985) Waming Label -
Label for ExPlanatory Wording
Guide for Organization and ImPlementation
of Laser Safety and Training Programs
Responsibility and Authority of Laser Safety Oflicer (LSO)
Deputy Laser SafetY Officers
Safety Committee
Responsibility of the Laser or Laser System Supervisor
Responsibility of Employees Working with or near Lase$
Training .
References
Recommended Training for LSOs and Employees
(lncludins but Not Limited to' OPerators'
Maintena-nce Personnel. and Service Technicians)
Routinely Working with or Around Lasers ' ' '
AppendixE
Medical Surveillance . .
Pumose of Medical Surveillance " " ' '
El,
82.
E3.
E4.
E5.
86.
w.
Medical Examinations '.. '
Medical Refenal Following Suspected or
Known Laser Injury
Records and Record Retentron
Access To Records
Epidemiologic Studies .... "'
References
AppendixF
Special Considerations ' ' '
Fl.
F2.
Compressed Gases
Cryogenic Liquids .. " "
PACE
73
73
74
74
75
/b
78
79
79
't9
80
80
80
8t
8l
82
83
83
83
84
85
85
85
85
6)
E5
86

SETION
F3.
F4.
F5.
F6.
Appendix
Gl.
c2.
Appendix H
Hl.
H2.
H3.
Lt4.
Ventilaiion
Ionizing Radiation
Toxic Materials
References
Biological Effects on the Eye and Sktn .
Minimal Biologicai Effects of Laser
Radiation on the Eye .. '. '
Biological Effects of Laser
Radiation on the Skin . . . .
Measurements
RadiomearicMeasurements .
Radiant Exposure Profiles and Radiant Exposure
Estimates for Pulsed Lasers .
Beam Divergence
References
PACE
86
86
86
86
87
8'1
89
90
90
90
90
90

American National Standard
for the Safe Use of Lasers
1. General
1.1 Scope. This standard provides reasonable and
adequate guidance for the safe use of lase$ and laser
syslems.
1.2 Application. The objective of this standard is to
pmvide reasonable and adequate guidance for the
safe use of lasen and laser systems. A practical
means for accomplishing this is first to classify lasers
and laser systems according to their relative hazards
and then 1o specify appropriate conrols for each
classification.
The basis of the hazard classincation scheme in Section
3 of this standand is the ability of the primary
laser beam or reflected primary laser beam to cause
biological damage to the eye or skin during intended
use. For example, a Class I laser is one that is considered
to be incapable of producing damaging radiation
levels and is, therefore, exempt from any control
measures or other forms of surveillance. Class 2
lasers (low-power) are divided into two subclasses, 2
and 2a. A Class 2 laser emits in the visible portion of
the spectrum (0.4 to 0.7 !rm) and eye protection is
normally afforded by the aversion response including
the blink reflex. Class 3 lasers (medium-power) are
divided into two subclasses, 3a and 3b. A Class 3
laser may be hazardous under direct and specular
reflection viewing conditions, but the diffuse
reflection is usually not a hazard. A Class 3 laser is
normally not a fire hazard. A Class 4 laser (highpower)
is a hazard to the eye and skin from the dircct
beam and sometimes from a diffuse reflection and
also can be a fire hazard,
It must be recognized that the classification scheme
given in this standard relates specifically to the laser
product and its potential hazard, based on op€rating
characterisdcs. However, the conditions under which
the laser is used, the level of safety training of individuals
usiog the laser and other environmental and
personnel factors are imponant considerations in
determining lhe full extent of safety control measures.
Since such situations require informed judgments
by responsible persons, major responsibility
for such judgments has been assigned to a person
with the requisite authority and responsibility,
namely the Laser Safety Officer (LSO).
Lasen or laser systems certified for a specific class by
a manufacturer in accordance with the Federal Laset
Product Performance Standard may be considered as
fulfilling alt claJsification requirements of this standard.
In cases where the laser or laser system
classification is not provided or where the class level
may change because of th€ addition or deletion of
engineering conrol measures (see 4.3), the laser or
laser system shall be classified by the LSO in accordance
with the descriptions given in Section 3 or the
methods described in Section 9, or both.
The recommended stepwise procedure for using this
standard is as follows:
(l) Determine the appropriate class of laser or laser
syslem,
(2) Comply with the measurcs specified for that class
of laser or laser system, using the following table as a
guide. This procedure will in most cases eliminate
the need for measurement of laser radiation, quantitative
analysis of hazard potential, or use of the Maximum
Permissible Exposure (MPE) values given in
Section 8 of this standard.
Class Control Measur€s Medical Surveillance
I
2
2a
3a
3b
4
Not applicable*
Applicable
Applicable
Applicable
Applicable
Appticable
Not applicable
Not applicable
Not applicable
Not applicable
Applicable
Appticable
* During normal oJrration and mainlenance only Alignment
and service procedurcs ofan embedded Chss 2. 3, or 4 laser
shatl rcquire conuol or adminislmtive procedures appropdale
to theclass during thes€ functions.
For quantitatiye evaluation of the hazard associated
with a given laser or laser syslem, Sections 8 and 9
should be consulted. To use the MPE values in Section
8, first determine whether there is a possibility of
intrabeam viewing (in which case the intrabeam MPE
criteria in 8.2 shalt be used) or whether a hazardous
diffuse reliection is being viewed (in which case the
MPE values for an extended source as given in 8.3 or

o
AMERICAN NATIONAL STANDARD ZI36.I-I986
the intrabeam MPE values as given in 8.2 may be
applicable). (See Figs. Bl, 82, and 83 in
Appendix B for illustrated viewing conditions-)
For the purposes of this standard, except for shortdistance
viewing of small diameter focused Class 3
lasers (see 3.4.1.3), only Class 4 lasers are capable of
producing hazardous diffuse reflections; hence calculations
for viewing diffuse reflections from Class l, 2,
and 3 systems are normally unnecessary.
The laser hazard classification system is based
entirely on the laser radiation emission. Other ancillary
hazards must be dealt with separately and are
addressed in Section 7 (Special Considerations).
Other special application standards within the 2136
series may have provisions which are exceptions to
the requirements of this standard. Each exception is
valid only for applications within the scope of the
standard in which it appears.
1.3 Laser Safety Officer (LSO)
1.3.1 General, An individual shall be designated
the Laser Safety Officer (LSO) with the authority and
responsibility to monitor and enforce the control of
laser hazards, and to effect the knowledgeable evalua-
(ion and control of laser hazards.
Depending on the extent and numb€r of laser installations,
the position of LSO may or may not be a full
time assignment. In some instances, designation of
an LSO may not be required. Such instances could
include operation and maintenance which are limited
to Class I and Class 2 lasers. However, under some
circumstances it may be necessary to designate an
LSO for example, if service is performed on a laser
product having an embedded Class 3a, Class 3b, or
Class 4laser. In such iostances, the designation ofan
LSO may be the responsibility of the organization
requiring access to the embedded laser or laser system,
such as the service company or organization.
There shall be a designated LSO for all circumstances
of operation, maintenance, and service of a Class 3a,
Class 3b or Class 4 laser or laser system.
1.3,2 LSO Specific Responsibililies
13.2.1 Classification. The LSO shall classily,
or verify classifications, of lasers and laser systems
used under the LSO's jurisdiction.
1.3,2.2 Hnard Evaluation. The LSO shall be
responsible for hazard evaluation of laser work areas,
including the establishment of Nominal Hazard
Zones (NHZ). (See 3.4.)
2
1.3.2.3 Control Measures. The LSO shall be
responsible for assuring that the prescribed control
measures are in effect, recommending or approving
substitute or altemate control measures when the primary
ones are not feasible or practical, and periodically
auditing the functionability of those controls
measures in use.
13.2.4 Procedure Approvals, The LSO shall
approve standard operating procedures, alignment
procedures, and other procedures that may be part of
the requirements for administrative and procedural
control measures.
1,3.2.5 Protective Equipment. The LSO shall
recommend or approve protective equipment i.e.,
eyewear, clothing, barriers, scrcens, etc., as may be
required to assure personnel safety. The LSO shall
assure that protective equipment is audited periodically
to ensure proper working order.
1,3.2.6 Signs and Labels. The LSO shall
approve the wording on area signs and equipment
labels.
1.3.2.7 Facility and Equipment. The LSO
shall approve laser installation facilities aod laser
equipment prior to use. This also applies to
modification of existing facilities or equipment.
1.3.2.8 Training, The LSO shall assur€ that
adequae safety education and training is provided to
laser area penionnel.
1.3.2.9 Medical Surveillance. The LSO shall
determine the personnel categories for medical surveillance.
(See 6.2)
1.3,2.10 Additional. Additional recommended
duties of the LSO are included in Appendix D.
2. Definitions
The definitions of the lerms listed below are based on
r pragmatic rathor than u basic approach. The tcrms
delined are therefore limited to those actually used in
this standard and its appendixes and are in no way
intended to constitute a dictionary of terms used in
the laser lield as a whole.
absorption. Transformation of radiant energy to a
differenr form ofenergy by interaction with matter.
accessible emission limit (AEL). The maximum
accessible emission level p€rmined wiftin a particular
class.

accessible radiation. Radiation to which it is possible
fbr the humiln eye or skin to be cxposed in nonuill
usage.
(Inmi^. See limiting dngular subtense.
apertDre. An opening through which radiation can
pass.
apparent visual angle. The angular subtense of the
source as calculated from source size and distance
from the eye. It is not the beam divergence of the
source. (See 8.1 for criteria.)
attenuation. The decrease in the radiant flux as it
passes
through an absorbing or scattering medium.
average power. The total energy imparted during
exposurc divided by the exposure duration.
aversion response. Movement of the eyelid or the
head to avoid an exposure to a noxious stimulant or
bright light. It can occur within 0.25 s, including the
blink reflex time.
beam. A collection of rays which may be parallel,
divergent, or convergent,
beam diameter. The distance between diametrically
opposed points in that cross-seciion of a beam where
the power per unit area is l/e (0.368) tim€s that of the
peak power per unit area.
blink reflex. See aversion response,
calorim€ter. A device for.measuring the total
amount of energy absorbed from a source of electromagnetic
radiation.
carcinogen. An agent potentially capable of causing
cancer.
coherent. A light beam is said to be coherent when
the electric vector at any point in it is related to that at
any other poiDt by a definite, continuous function.
collimated beam. Effectively, a "parallel" beam of
Iight with very low divergence or convergence. (See
8.1 for criteria.)
conjunctival discharge (of the eye). Increased
secretion of mlrcus from the surface of the eyeball.
continuous wave (cw). The output of a laser which
is operated in a continuous rather than a pulsed mode.
In this standard, a laser operating with a continuous
output for a period >0.25 s is regarded as a cw laser.
controlled area, An area where the occupancy and
activity of those within is subject to contml and
supelvision for the purpose of protection from radiation
hazards.
AMERICAN NATIONAL STANDARD ZI 36. I -I 986
cornea. The transparent outer co&t of the human eye
which covers the iri$ and ahe cryst{lline lens. The
comea is the main refracting element of the eye.
cryogenics. The branch of physics dealing with very
low temperatures.
depigmentation. The rcmoval of the pigment of
melanin granules fmm human tissues.
dermatology. A branch of medical science that deals
with the skin, iis structure, functions, and diseases,
diffraction. Deviation of part of a beam, determined
by lhe wave nature of radiation and occuring when
the radiation passes the edge ofan opaque ob$iacle.
diffuse reflection. Change of the spatial distribution
of a beam of radiation when it is reflecied in many
directions by a surface or by a medium.
divergence. The increase in the diameter of the laser
beam with distance from the exit aperture. The value
gives the full angle at the point where the laser
energy or irradiance is l/e (36.8%) of the maximum
value. For the purposes of lhis standard, divergence
is taken as the full angle, expressed in radians, of the
beam diameter measured between those points which
include laser energy or irradiance equal to l/e of the
maximum value (the angular extend of a beam which
contains all the radius vectors of the polar curve of
radiant intensity that have length rated at 36.8Eo of
the maximum). Sometimes this is also refened to as
beam spread,
edema. The swelling of tissues in the human body
due to the presence of abnormal amounts of fluid in
the extracellular spaces.
electromagnetic radiation. The flow of energy consisting
of orthogonally vibrating electric and magnetic
fields lying transverse to the dir€ction of propagation.
X-ray, ulraviolet, visible, infrared, and radio
waves occupy various portions of the electromagnetic
spectrum and differ only in frequency and
wavelength.
embedded laser. A laser with an assigned class
number higher than the inherent capability of the
laser system in which it is incorporated, where the
systems lower classiflcation is appropriate due to the
engineering fearures limiting accessible emission.
energy. The capacity for doing work. Energy content
is commonly used to characterize lhe output from
pulsed lasers, and is generally expressed in joules (J).
epidemiologJr. A brarch of medical science that
deals with the incidence, distribution and control of

AMERICAN NATIONAL STANDARD ZI36.I-I986
disease in a population.
€pithelium (of ahe cornea). The layer of cells fbrming
the outer surface of the comea.
erythema. Redness of the skin due to congestion of
the capillaries.
extended source. A source of radiation that can be
resolved by the eye into a geometrical image, in contrast
10 a point source of radiation, which cannot be
resolved into a geome*ical image. (See 8.1 for criteria.)
failsafe interlock. An interlock where the failure of
a single mechanical or electrical component of the
interlock will cause the system to go into, or remain
in, a safe mode.
focal length. The distance from the secondary nodal
point of a lens to the primary focal point. In a thin
lens, the focal length is the distance between the lens
and the focal point.
focal point. The point toward which radiation converges
or from which radiation diverges or appears to
diverge.
fundus. See oculdr fundus.
funduscopic. Examination ofthe fundus (rear) ofthe
natf-power poirrt. The value on either the leading or
trailing edge of a laser pulse at which the power is
one-half of its maximum value.
hertz (Hz). The unit which expresses the frequency
of a periodic oscillation in cycles per second.
infrar€d radiation. Electromagnetic radiation with
wavelengths which lie within the range O.?;rm to
I mm.
integrated radiance. The integral of the radiance
over the exposure duration. Also known as pulsed
radiance. Unit: joules per square centimeter per
steradian (J 'cm-2 sil).
intrabeam viewing. The viewing condition whereby
the eye is exposed to all or pan of a laser beam where
the visual angle is less than clmin (see limiting angular
subtense). (See Figs. Bl and 82.)
ionizing radiation. Electromagnetic radiation having
a sufficiently large photon energy to directly ionize
atomic or molecular systems with a single quantum
event,
iris. The circular pigrnented membrane which lies
behind the comea of th€ human eve. The iris is
perforated by the pupil.
irradiance (al a poinl of a surface). Quotient of the
radiant flux incident on an element of the surface containing
the point at which inadiance is measured, by
the area of that element. Unit watt per square centimeter
(W ' cm-2).
Jaeger's tesa. Samples of type of various sizes
printed on a card for testing close visual acuity. An
analogue of the Snellen chan for distant visual acuity.
joule. A unit of energy. I joule = I watt ' second.
Lambertian surface. An ideal surface whose emitted
or rcflected radiance is independent of the viewing
angle.
laser. A device which produces an intense, coherent,
directional beam of light by stimulating electronic or
molecular transitions to lower energy levels. An
acmnym for Light Amplification by Stimulated
Emission of Radiation.
laser safety officer (LSO). One who has authority to
monitor and enforce the conhol of laser hazards and
effect the knowledgeable evaluation and control of
laser hazards.
laser system. An assembly ofelectrical, mechanical,
and optical components which includes a laser.
lesion. An abnormal change in the structure of an
organ or purt due to injury or disease.
limiting angular sublense (dmin). The apparent
visual angle which divides intrabeam viewing from
extended-source viewing, (See 8.1 for criteria,)
limiting aperture. The maximum diameter of a circle
over which inadiance and radiant exoosure can be
averaged,
limiting exposure duration (tma,(). An exposure
duration which is specifically limited by the design or
intended use(s). (See Section 8 for examples.)
lossy medium. A medium which absorbs or scatters
radiation passing thruugh i1.
maint€nsnce. Performance of those adjustments or
procedures specified in user information provided by
the manufacturer with the laser or laser system, which
are to be performed by the user to ensure the intended
performance of the product, It does not include
operation ot seruice as defined in this section.
maximum permissible exposure (MPE). The level
of laser radiation to which a person may be exposed
without hazardous effecl or adverse biological
changes in the eye or skin. The criteria for MPE for

lhe eye and skin are detailed in Section 8
meter. A unit of length in the international system of
units; cunently defined as a ' fixed number of
wavelengths, in vacuum, of the orange-red line of the
spectrum of krypton 86. Typically, the meter is subdivided
into the following units:
Centimeter (cm) = l0-2 m
Millimeter (mm) = l0-r m
Micrometer (pm) = l0{ m
Nanometer (nm) = lOa m
nominal hazard zone (NHZ). The nominal hazard
zone describes the space within which the level of the
direct, reflected or scattered radiation during normal
operation exceeds the applicable MPE. Exposure
levels beyond the boundary of the NHZ are below the
appropriate MPE level.
nominal ocular hazard distance NOHD). The dislance
along the axis of the unobstructed beam from
the laser to th€ human eye beyond which the inadiance
or radiant exposure during normal operation is
not expected to exceed the appropriate MPE.
ocular fundus. The back of the eye. May be seen
through
the pupil with an ophthalmoscope.
operation. The performance of the laser or laser system
over the full range of its intended functions (normal
operation). It does not include maintenance or
service as defined in this section.
ophthalmoscope. An instrument for examining the
interior offte eye.
optical density (D1). Logarithm to the base ten of
the reciprocal of the transmittance: D1=-log1e t1,
where t1 is transmittance.
- optically pumped laser. A laser in which the clechons
are excited into an upper energy state by the
absorption of light from an auxiliary light source.
photophobia. An unusual intolerance of light. Also,
an aversion to light usually caused by physical
discomfon upon exposure to light.
photosensitizers. Substances which increase the sensitivity
of a material io irradiation by electromagnetic
energy.
pigment epithelium (of the r€tina). The layer of
cells which contain brown or black pigment granules
next to and behind the rods and cones.
point source. A source of radiation whose dimensions
are small enough, compared with the distance
between source and receptor, to be neglected in
AMERICAN NATIONAL STANDARD ZI36.I -1986
calculations. Equivalent for the purpose of this standard
to intrabeam viewing. (See 8. t for criteria.)
power. The rate at which energy
hansfered, or received. Unit: watts
second).
prf. Abbreviation for pulse-repetition
(See repetitively pulsed laser.)
is emitted,
(oules per
frequency.
protective housing. An enclosure that surrounds the
laser or laser system that prevenls access co laser radiation
above the applicable MPE level. The aperture
through which the useful beam is emitted is not pan
of the protective housing. The protective housing
may enclose associated optics and a work station and
shall limit access to other associated radiant energy
emissions and to electrical hazards associated with
components and tefminals.
pulse duration. The duration of a laser pulse; usually
measured as the time interval between the halfpower
points on the leading and trailing edges of the
pulse.
pulsed laser. A laser which delivers its energy in the
form of a single pulse or a train of pulses. ln this
standard, the duration ofa pulse

AMERICAN NATIONAL STANDARD 2I36.I.I986
Quotient of the radiant flux leaving the source and
propagated in an element of solid angle containing
the given direction, by the element of solid angle'
Unit: watts per steradian (W ' sf').
radiant power. See radiant flux'
radiometry. A branch of science which deals with
the measurement of radiation. For the purposes of
this standard, radiometry will be limited to the measurement
of infrared, visible, and ultraviolet rddiation.
Rayl€igh scataering. Scattering of radiadon in the
course of its passage thtough a medium containing
panicles whose sizes are small compared with the
wavelength of the radialion.
reflectance. The ratio of total reflected radianl power
to total incident power. Also called re.fecrivity.
reflection. Deviation of radiation following
incidence on a surface.
rep€titively pulsed laser. A laser with multiple
pulses of radiant energy occurring in sequence with a
prf ) I Hz.
retina. The sensory membrane which receives the
incident image formed by the comea and lens of the
human eye. :Ihe retina lines the inside ofthe eye.
scannlng laser. A laser having a time-varying direction,
origin, or pa em of proPagation with respect to
a stationary frame of reference.
scintillation. The rapid changes in irradiance levels
in a cross-section of a laser beam.
service. The performance of those procedures or
adjustments describ€d in the manufacturer's servlce
instructions which may affect any asPect of the performance
of lhe laser or laser system. It does not
include maintenance or operation as defined in this
section.
shall. The word "shall" is to be understood as mandatory.
should. The word "should" is to be understood as
advisory.
solid angle. The three-dimensional angular spread at
the vertex of a cone measured by the area intercepted
by the cone on a unit sphere whose center is the vertex
of the cone. It is expressed in steradians (sr).
source. A laser or a laser-illuminated reflecting surface.
specular r€fl€ction. A mirrorlike reflection.
steradian (sr). The unit of measure for a solid angle'
6
There are 4ft steradians about any Point in space.
stromal haze (of the cornea). Cloudiness in the
connective tissue or main body of the comea.
surface exfoliation (of th€ cornea). A stripping or
peeling off of the surface layer of cells from the cornea.
tonometry. Measurcment of the pressurc (tension)
of the eyeball.
transmission. Passage of radiation through a
medium.
transmittance. The ratio of total tmnsmitted radiant
power lo total incident radiant power.
ultraviolet radiation. ElecFomagnelic radiation
with wavelengths smaller than those of visible radiation;
for the purpose of this standard, 0.2 to 0.4 pm.
visible radiation (light). Electromagnetic radiation
which can b€ detected by the human eye. This term
is commonly us€d to describ€ wavelengths which lie
in the range 0.4 to 0.7 Fm.
$att. The unit of power or radiant flux. 1 watt = i
joule per second.
wavelength, The disknce between two successive
points on a periodic wave which have the same
phase,
3, Hazard Evaluation and Classification
3.1 General. Three aspects of the application of a
laser or laser system influence the total hazard
evaluation and thereby influence the application ol
contlol measures:
(1) The laser or laser sys@m's capability of iniurinS
personnel
(2) The environment in which the laser is used
(3) The personnel who may use or be exposed to laser
radiation
The laser classification scheme is based on aspect ( I )
Laser and laser systems classilied in accordance with
this \tandard shall be labeled with the appropriatt
hazatd classification (see 3.3). Classification labeling
used in conformance with the Federal Laser Producl
Performance Standard may be used to satisfy lhis
labeling requirement. lt should be noied that in some
cases there may be differences beMeen this standard
and the Federal L,aser Product Performance Standard'

(See Appendix C for references.) If the laser
b€en modified subsequent to classification by
manufacturer, the guidance in 4.10 shall be used.
has
the
Any laser or laser system shall be classified according
to its accessible radiation during normal operation.
Aspects (2) and (3) vary with each laser application
and cannot be readily standardiud. The total hazard
evaluation procedure shall consider all three aspects,
although in most cases only aspect (l) influences the
conrol measures which are applicable.
The detailed hazard evaluation or the classification of
a laser or laser system as outlined in this section
should not be attempted by personnel untrained in
laser safety or optical engineering/physics. When it
is necessary for the LSO to effect such an eyaluation,
it should be based on adequate training or
knowledgeable assistance so that the calculations and
risk determinations outlined in this section will be
accomplished. Errors in such analyses could result in
injuries of personnel and should not be taken lightly.
3,2 Laser Considerations. The LSO or knowledgeable
individual responsible for laser classification
shall ensure that laser-output data are valid in accordance
with Section 9 (Measurements). Classification
shall be based on the maximum output available for
the intended use.
3.2.1 Multiwavelength Lasers. The classification
of lasers or laser syslems capable of emitting
numemus wavelengths shall be based on the most
hazardous possible op€ration. (See 83, examples l2
and 13.)
3.2.1,1 A multiwavelength laser which by
dssign can operate only as a single-wavelength laser
shall be classified as a single-wavelengrh laser.
3.2.1.2 A multiwavelength laser which by
design can operate over two or more wavelength
regions (as defined in Section 8) shall require
classification in each region of operalion. Thc
apprcpriate control measures for each region shall be
taken.
3.2.2 Repetitively Pulsed Lasers. The evaluation
of repetitively pulsed laseE or exposures requires the
use of cenain correction factors. (See Section 8.)
3.2.3 Radiometric Parameters of the Laser
Required for Determlnlng Laser Hazard
Classification
AMERICAN NATIONAL STANDARD 2136.I - I986
3.2.3.1 Classification of essentially all lasers
requires the following Parameters:
(l) Wavelength(s) or wavelength range
(2) For cw or repetitively Pulsed lasers: average
Dowcr output and limiting exposure durdtion 1,,,.
inherent in the design or intended use of the laser or
laser system
(3) For pulsed lasers: total energy per pulse (or peak
power), pulse duration, prf, and emergent beam radianl
exposure
3.23.2 Classification of extended-source lasers
or laser systems (such as laser arays, injection laser
diodes, and lasers having a permanent diffuser within
the output optics) requires, in addition to the Parameters
listed in 3.2.3.1, knowledge of the laser source
radiance or integrated radiance and ihe maximum
viewing angular subtense.
3,2.3.3 Class I AEL. To determine the laser's
potenlial for producing injury, it is necessary to consider
not only the laser outPut irradiance or radiant
exposure, but also whether a hazard would exist if the
total laser beam power or pulse energy were confined
to the area of the limiting aperture for the applicable
MPE (see Table 9).
The Class I AEL is defined in two different ways'
depending on whether the laser is considered a point
source or an extended source (an unusual case).
3.2.3.3.1 Most lasers can be considered Point
sources. For such lasers, the Class I AELs shall be
determined by the pmduct of two factors:
( l) The intrabeam MPE for the eye (see Figs. 4 and
6) for the limiting exposure duradon
(2) The area of the limiting apenure for the MPE (i.e"
1, 7 or l I mm as applicable; see Table 9) in cm'
That is, AEL = MPE x (arca of limiting aperturc)
3.2.33.2 For exlcndcd-vrurce lasen or laser
systems which emit in the sPectral range 0'4 to
1.4 pm, the Class I AELs shall be determined by a
power or energy outPut such that:
(l) The source radiance does not exceed the MPE
(see Table 6) when the source is viewed at the
minimum viewing dista.nce
(2) A theoretically perfect optical viewing system
(50-mm limiting entlance aperture, T-mm exit aperture)
would collect lhe entire laser beam output

AMERICAN NATIONAL STANDARD 2I36.I-I986
If this definition is difficult to apply, the definition in
3.2.3.3.1 may be applied and will result in a conservative
Class I AEL.
3,2.3.3.3 The Class 2 AEL's shall be determined
in the same manner as Class I AEL'S except
the MPE values are based on an exposure duration of
0,25 s (aversion response). For cw point source conditions,
the MPE is 2.5 mW' cm-r.
3.3 Laser and Laser Sysaem Hazard Classification
Definitions. Tables I and 2 offer a summary of levels
for laser and laser system classification: Table I
for cw lasers with an emission duration > 0.25 s and
Table 2 for pulsed lasers with an emission duration
< 0.25 s. (See Appendix A, Examplcs of
Classification of Lasers or Laser Systems).
3,3,1 Class I Las€rs and Laser Systems
3.3.1.1 Any laser, or laser system containing a
laser. that cannot emit accessible laser radiation levels
in excess of the Class I AEL for the maximum
possible duration inherent in the design or intended
use of the laser or laser system is a Class I laser or
laser system during normal operation and is exempt
from all control measures or other forms of surveillance
with the exception of applicable requirements
for embedded lasers. See 4.3.1.1. The exemption
strictly applies to emitted laser radiation hazards and
not to other potential hazards (see Section 7. Special
Considerations).
3.3.1.2 Lasers or laser systems intended for a
specific use may be designated Class I by the LSO on
the basis of that use for a t "* classification duration
less than 3 x lOa s, provided that the accessible laser
radiation does not exceed the corresponding Class I
AELs for the maximum possible duration inherent in
the design or intended use of the laser or laser system.
3.3,2 Class 2 and Class 2a Visible Lasers and
Laser Systems
3.3,2.1 Class 2 lasers and laser systems incl ude:
(l) Visible (0.4 to 0.7 pm) cw lasers and laser systems
which can emit accessible radiant Dower
exceeding the Class I AEL for the maximunr possible
duration inherent in the design or intended use of the
laser or laser system, but not exceeding I mW
(2) Visible (0.4 to 0.7 pm) repetitively pulsed lasers
and laser systems which can emit accessible radiant
power exceeding the appropriate Class I AEL for the
maximum possible duration inhercnt in the design or
intended use of the laser or laser svstem. but not
R
exceeding the Class I AEL for a 0.25 s exposure
duration
3^1,2,2 Visible (0.4 to 0.7 pm) laser and laser
systems intended for a speciic use where the output
is not intended to be viewed shall be designated
Ctass 2a by the LSO, provided that the accessible
radiation does not exceed the Class I AEL for an
exposure duration less than or equal 1o ld s.
3.3.3 Class 3a and Class 3b Lasers and l,aser
Systems
3J.3.1 Class 3a and Class 3b laser and laser
systems include:
( l) Infrared ( 1.4 Fm to I mm) and ultraviolet (0.2 to
0.4 pm) lasers and laser systems which can emit
accessible radiant power in excess of the Class I AEL
for the maximum possible duration inherent in the
design of the laser or laser system, but which
(a) cannot emit an average radiant power in excess of
0.5W for 20.25s or (b) cannot produce a mdiant
exposure of l0J'cm-2 within an exposure time
< u.lJ s
(2) Visible (0.4 to 0.7 pm) cw or rcpetitively pulsed
lasers and laser systems which produce accessible
radiant power in excess of the Class I AEL for a
0.25 s exposure time (l mW for a cw laser), but
which cannot emil an average radiant power greater
than O.5 W
(3) visible and near-infrarcd (0.4 to 1.4 pm) singlepulsed
lasers which can emit accessible radiant
cnergy in excess of the Class I AEL but which cannot
produce a radiant exposurc that exceeds
10 J 'cm-z or produce a hazardous diffuse reflection
as given in Table 3
(4) Near-infrared (0.7 to 1.4 pm) cw lasers or pulsed
lasers which can emit accessible radiant power in
excess of the Class I AEL for the r,"* inherent in the
design or intended use of the laser or laset system,
but which cannot emit an average power of 0.5 W or
greater for periods ) 0.25 s
33.3.2 All Class 3 lasers and laser systems
which have an accessible output power between I
and 5 times the Class I AELs for wavelengths less
than 0.4 pm or greater than 0.7 pm, or 5 times the
Class 2 AELs for wavelengths between 0.4 pm and
0.7 pm, are Class 3a. See 4.7.3.1 .
3.3.3.3 All Class 3 lasers and laser systems
which do not meet the requirements of 3.1.3.2 shall
be classified as Class 3b.

3.3.4 Ctass 4 Lasers and Laser Systems. Class
4 lasers and lsser systems include:
(l) Ultraviolet (0.2 to 0.4 pm) and infrared ( 1.4 pm to
I mm) lasers and laser systems which (a) emit an
average accessible radiant power in excess of 0.5 W
for periods >,0.25 s or (b) produce a radiant exlxrsurc
of l0 J ' cm-' for an exposure duration of < 0.25 s
(2) Visible (0.4 to 0.7 ltm) and near-infrared (0.7 to
1.4 pm) lasers and laser systems which (a) emil an
average accessible radiant power of 0.5 w or greater
for periods ) 0.25 s or (b) produce a radiant exposure
in excess of lOJ'cm-2. or a hazardous dill'use
reflection as defined in Table 3. for Deriods < 0.25 s
3.4 Environment in Which the Laser is Used. Following
laser or laser system classification, environmental
factors rcquire consideration. Their importance
in the total hazard evaluation depends on the
laser classification. The decision by the LSO to
employ additional control measures not specifically
required in Section 4 of this standard, (or eliminate
some thaa are), is influenced by environmental considerations
principally for Class 3 and Class 4 lasers
or laser Systems.
The probability of personnel exposure to hazardous
laser radiation shall be considered. This may be
influenced by whether the laser is used indoors or
outdooni. Examples of indoor applications include
lasers used in a classroom, a machine shop, a closed
research laboratory or on a factory production line.
Examples of outdoor applications include lasers used
in a mining tunnel, a highway construction site, a
military laser range, the atmosphere above occupied
areas, a pipeline construction uench or in outer space.
Other environmental hazards (see Section 7) shall
also be considered.
If exposure of unprotected personnel to the primary
or specularly reflected beam is possible, determination
of the inadiance or radiant exposure for ihe primary
or specularly reflected beam at that specific
location, or of the radiance of an extended source, is
required. (See Appendix B.)
Where applicable, e.9., in the presence of unenclosed
Class 3b and Class 4 beam paths, the LSO shall be
responsible for establishing the Nominal Hazard
Zone (NHZ). The NHZ describes the space within
which the level of direct, reflected or scattered radiation,
during normal operation, exceeds the applicable
MPE. If the beam of an unenclosed Class 3b or
Class4 laser or laser system is contained within a
region by adequate control measures lo protecl
AMERICAN NATIONAL STANDARD ZI36.I-I986
personnel from exposure to levels of radiation above
the approp ote MPE, thst region may bc considcrcd
ro conhin the NHZ. The NHZ may be determined by
information supplied by the laser or laser system
manufacturer, by measurement, or by using the
appropriate laser range equation or other equivalent
assessment as described in this $ection and
Appendix B
The LSO shall assure that consideration is given to
dir6ct, reflected and scattered radiation in the establishment
of boundaries for the laser conrolled area
(see4.3.10). [f operation or maintenance peEonnel
are required to be within the NHZ, appropriate control
measures shall be established (see Section 4).
During service, a temporary laser contf,olled area may
be required (see 4.3. t2).
Since the levels of radiation that escap€ the NHZ are
maintained at or below the appropriate MPE, no additional
controls are required outside the NHZ.
Viewing the main beam or a specular laser hrget with
an optical instrument is potentially hazardous due to
the instrument's light-gathering capability (see
4.3-5.2 and B4.5, examples 2l and 22). Use of such
optical systems may therefore effectively increase the
NHZ boundaries and must be considered in the
overall hazard analysis.
3.4.1 lndoor Laser Operations. ln general, only
the laser is considered in evaluating an indoor laser
operation if the beam is enclosed or is operated in a
controlled area. The step-by-steP procedure
described in 3.4.1.1 through 3.4.1.4 is recommended
fbr evaluaaion of the NHZ of laser and laser systems
when used indoors if there is a potential for exposure
of unprotected personnel. In this evaluation consider
all optics (lenses, mimors, fiber optics, etc.) which
are a perrnanent pan of the laser beam Path,
3.4.1.1 Step l. Detemine and evaluate the
NHZ of all possible beam paths. Include multiple
beam paths due to lack of fixed positioning and unintended
Lream paths due to unstable mounts, bearing
wear, vibration, etc]
3,4.1.2 Step l. Determine the NHZ for specular
reflections (as fi1)m optical surfaces).
3.4.1.3 Step tl. Determine the exient of hazardous
diffuse reflections if the emergent laser beam is
focused. Hazardori; diffuse reflections are possible
from a focused or imall-diameter beam of a Class 3
laser. However, the angular subtense of the source is
normally sufficiently small at all practical viewing
distances that intrabeam MPEs apply. Determine the

AMERICAN NATIONAL STANDARD 2I36. I. I 986
NHZ.
3.4.1.4 Slep 4. Determine the likelihood for
operation or maintenance personnel to be within the
NHZ during normal operation.
3.4.15 Step 5. Determine if other (nonlas€r)
hazards exist (see Section ?, Special Considerations),
3,4.2 Outdoor Laser Operaaions Over
Extended Distances. The total hazard evaluation of
a particular laser system depends on defining the
extent of several potentially hazardous conditions. In
this evaluation, consider all optics (lenses, mirrors,
fiber optics etc.) which are a permanent part of lhe
laser beam path. This may be done in a step-by-step
manner, as given in 3.4.2.I through 3.4.2.5.
3.4.2.1 Step l Determine the NHZ of the
laser, Calculations of radiant exposure or beam irradiance
as a function of ftrnge can be made with the
raDge equation for a circular beam (see Appendix B).
These calculated ranges are only estimates beyond a
few hundred meters. since uncertainties arise from
atmospheric effects (for example, scintillation due to
turbulence; see ?,6.3).
3.4.2.2 Step 2. Evaluate potential hazards
from transmission through windows and specular
reflections, Specular surfaces ordinarily encountered
(for example, windows and mirrors in vehicles and
windows in buildings) arc oriented vertically and will
usually reflect a horizontal beam in a horizontal
plane.
As much as 89o of the beam's original inadiance or
radiant exposure can be reflected toward the laser
from a clear glass window which is oriented perpendicular
to the beam. If the beam strikes a flat, specular
surface at an angle, a much greater percentage of
the beam can be reflected beyond or to the side of the
target area. If the beam strikes a still pond or other
similar surface at a grazing angle, effective
reflectivity also may be high. Specular reflective surfaces,
such as raindrops, wet leaves, and most other
shiny natural objects, seldom reflect hazardous radiant
intensities beyond a meter from thesc reflectors.
3.4.2.3 Step 3. Determine whether hazardous
diffuse reflections exist (see Table 3 and 8.3.2.3,
Examples 8 and 9). Determine the coresponding
NHZ.
3.4.2.4 Step 4. Evaluate the stabiliry of rhe
laser platfom to determine the extent of lateral range
control and the lateral constraints that should be
placed on the beam traverse. Determine the
l0
corresponding NHZ during normal operatlon.
3.4.2.5 Step 5, Consider the likelihood of people
being in the NHZ.
3.5 Personn€I. The personnel who may b€ in the
vicinity of a laser and its emitted beam(s), including
maintenance personnel, service personnel and the
operator, can influence the total hazard evaluation
and hence influence the decision to adopt additional
control measures not specifically required for the
class of laser being employed. This depends upon the
classification of the laser or laser system.
35.1 If children or others unable to read or und€rstand
waming labels may be exposed to potentially
hazardous laser radiation, the evaluation of the hazard
is affected and control measures may require
appropriate modifi cation.
3.5.2 The type of personnel influences the total
hazard evaluation. It must be kept in mind that for
certain lasers or laser systems (for example, military
laser rangefinders and some lasers used in the construction
industry), the principal hazard conrol rests
with the operator, whose responsibility is to avoid
aiming the laser at personnel or flat mirrorlike surfaces.
The following are considerations regarding operating
personnel and those who may be exposed:
( | ) Maturity ofjudgment of the laser user(s)
(2) General level of training and experience of laser
user(s) (that is, whether high school students, military
personnel, production line operators, scientists, etc.)
(3) Awareness on the part of onlookers that potentially
hazardous laser radiation may b€ present and
the relevant safety precautions
(4) Degree of training in laser safety of all individuals
involved in the laser's operation
(5) Reliability of individuals to follow standard
operating procedures (SOP) and recommended control
procedures
(6) Number of individuals and their location relative
to the pdmary beam or reflections, and potential for
accidental exposure
(71 Other hazards not due to laser radiation which
may cause the individuals to rEact unexpectedly or
which influence the choice of personnel protective
equipment
NOTE: Examples of typical lasers classified in accordance
with this standard are given in Appendix A. Examples of

AMERICAN NATIONAL STANDARD ZI36.I - 1986
diagnostic, therapeutic, or medical research purposes,
by or under the direction of qualified professionals
engaged in the healing arts. However, those administering
and assisting in the administering of the laser
radiation as well as the patient where applicable, shall
be protected by the control measures as outlined
hercin, and, as applicable, to the requirements as
specified in the American National Standard for Laser
Safety in Health Care Faciliries, ANSI Zt 36.3.
4.1.4 El€ctrical, Beam Int€raction, and other
Associated Hazards. The ancillary hazards associated
with the use of laser or laser systems can be
significant. For example, loss of life has occuned
during elecrical servicing and testing of laser equipment
incorporaiing high-voltage power supplies.
In addition, toxic fumes, particulates and intense
blackbody radiation (which can prcsent additional
eye hazards) may be released during the interaction of
laser energy with materials. The controls for associated
hazards are included in this section. and Section
?.
4.2 Laser Safety Officer (LSO). The LSO shall
have the responsibility and authority to monitor and
enforce the control of laser hazards and effect fte
knowledgeable evaluation and control of laser
hazards. This shall include, but not be limited to,
such actions as establishing an NHZ, approving standard
operating procedures (SOP's), avoiding
unnecessary or duplicate controls, seleclion ol allernate
controls and training. (See Sections l, 3, 5 and
Appendix D.)
4.3 Engineering Controls. The engineering control
measules fol a )aser ol laser sysrems are as specified
in4.3.1to4.3.15.
Although corimercial laser products ihanufactured in
compliance with the Federal Laser Product Pedormance
Standard will be certified by the manufacturer
and will incorporate some engineering controls, the
use of the additional conhols outlined in this section
shall be considered in order to reduce the potential lbr
hazard associated with some applications of lasers
and laser systems.
The engineering controls (performance features)
which are supplied by the mtmufacturer of cenified
products and are used in this documenl are described
in 4.3. l, 4.3.2, 4.3.-1, 4.3.4, 4.3.5. l, 4.3.7, 4.3.tt. 4.3.9,
and 4.3.14.
NOTE: Lasers and laser systems which have been altered
by other than the user may necessitatc rccenilication,
reclassilication and compliance reporl;ng under the
t1
requirements of the Federal Laser hoducl Performance
Standard.
4,3.1 Protective Housings: (All Classes). A protective
housing shall be provided (except as noted in
4.3. l.l ) for all classes of lasers or laser systems. (See
4.4.8) The pmtective housing may require interlocks
(4.3.2) and labels (4.7).
43,1.1 Laser Use without Protecaive Housing:
(All Classes). In some circumsiances, such as
research and development and during the manufacture
of la.sers, operation of laser or laser systems
without a protective housing may become necessary.
In such cases the LSO shall determine the hazard and
ensure that controls are instituted appropriate to the
class of maximum accessible emission to assure safc
operation. These controls may include, but not b€
limited to:
(l) access restriction (see 4.3.10)
(2) eye protection (see 4.6.?)
(3) area controls (see 4.3.10 and 4.3.1 l)
(4) barriers, shrouds, beam stops etc. (see
4.3.8)
(5) administrative and pmcedural controls
(see 4.4)
(6) education and training (Section 5)
43,2 Interlocks on Removablc Protective
Housings (Embedded Class 3a, Class 3b or Class
4). Protective housings which enclose embedded
Class 3a, Class 3b or Class 4 lasers or laser systems
shall be provided with an interlock system which is
activated when the protective housing is intended to
be opened during operation and maintenance. The
interlock or interlock sysrem shall be designed to
prevent access to laser radiation above the applicable
MPE. The interlock may, for example, be electrically
or mechanically interfaced to a shutter which interrupts
the beam when the protective housing is
removed (see 7.4.2 for electrical design criteria).
Failsafe interlocks shall be provided for any ponion
of the protective housing which, by design, can be
removed or displaced during normal operaiion and
maintenance and thereby allows access to laser radialion
of an embedded Class 3b or Class 4 laser. One
method to fulfill the fail-safe requirement is the use
oI redundanl electrical series-connected interlocks.
The protective housing interlock shall not be defeated
or overridden during operation.

t
The LSO should periodically confirm that protective
hou$ing interlocks are functional.
Adjustments or procedures during service on lasers or
laser systems containing interlocks shall not cause the
interlocks to be inoperative when the equipment is
restored to its normal operational condition, except ns
noted in 4.3.1.1.
4.3.3 Service Access Panels: (Embedded Class
3b or Class 4). Ponions of the protective housing
which are intended to be removed only by service
personnel and permit direct access to laser radiation
associated with an emb€dded Class 3b or Class 4
laser or laser system shall either:
(l) be interlocked (fail-safe interlock nol
required), or
(2) require a tool for removal and shall have an
appropriate warning label (see 4.7) on the panel.
If the interlock can be bypassed or defeated, a waming
label with the appropriate indicarions shall be
located on or near the interlock. The design shall not
permit the service access panel to be replaced with
the interlock bypassed or defeated.
4.3,4 Master Switch: (Class 3b or Class 4), A
Class 3b laser or laser system should be provided
with a master switch. A Class 4 laser or laser system
shall be provided with a master switch. This mdster
switch shalt be operated by a key, or by a coded
access (such as a computer code).
The authority for access to the master switch shall be
vested in the appropriate supervisory personnel. The
master switch shall be disabled when the laser or
laser system is not intended to be used.
4.3.5 Vlewing Portals and Collecting Opaics
4.3.5.1 Viewing Portals and Display Screens:
(Class 2' Class 3a, Class 3b or Class 4). All viewing
ponals and/or display screens included as an
integral part of a Class 2, Class 3a, Class 3b or
Class 4 laser or laser system shall incorporate a suitable
means (such as interlocks, filters, attenuators) to
maintain the laser radiation at the viewing position at
or below the applicable MPE for all conditions of
operation and maintenance.
4.3,5.2 Collecting Optics (Class 2, Class 3a,
Class 3b or Class 4). All collecting optics (such as
lenses, telescopes, microscopes, endoscopes, etc.,)
intended for viewing use with a laser or laser system
shall incorporate suitable means (such as interlocks,
filters, attenuators) !o maintain the laser radiation
transmitted through the collecting optics to l€vels at
AMERICAN NATIONAL STANDARD 2136,I.I986
or below the appropriate MPE, under all conditions
ol operation and maintenance.
NOTE: Normal or prescription eyeweal are nor considered
collecting optics.
4.3.6 Beam Paths: (Class 3b or Class 4). Control
of lhe laser b,:am path shall be accomplished as
described in the following sections. (AIso, see
Appendix B.)
4.3.6.1 Totally Unenclosed Beam Path:
(Class 3b or Class 4). In applications of Class 3b or
Class 4 lasers or laser systems where fte entire beam
path is unenclosed, a laser hazard analysis shall be
effected by the LSO to establish the NHZ if not furnished
by the manufacturer or available as part of the
classification (see 3.4).
The analysis will define the area where laset radiation
is accessible at levels above the appropriate MPE and
will define the zone requiring control measures. A
laser controlled area shall be established in this zone
(see 4.3.10 and 4.3. | | ) and appropriate control measures
shall be implemented based upon the
clussification associated with the maximum level of
accessible laser radiation.
4.3.6.2 Limited Open Beam Path: (Class 3b
or Class 4). In applications of Class 3b or Class 4
lasers or laser systems where the beam path is
confrned by design to significantly limit the degree of
accessibility of the open beam, a hazard analysis shall
be effected by the LSO ro establish the NHZ
(see 3.4). The LSO shall establish controls approPriate
to the magnitude and exte[t of the accessible radiallon,
Frequently the hazard analysis will define an
extremely limited NHZ and procedural controls can
pmvide adequate Protection.
4.3.6.3 Enclosed Beam Palh: (All Classes).
In applicaiions of laser or laser systems where the
entire beam path is enclosed, and the enclosure
fulfills all requirements of a protective housing (i.e.,
limits the exposure to the MPE; see 4.3.1 and 4.3 2),
the requirements of Class I are fullilled and no
further controls are required.
When the protective housing requirements are temporarily
relaxed, such as during service, the LSO
shall establish the appropriate controls. These may
include a temporary area control (see4.3.12) and
adminisrative and procedural controls (see 4.4).

AMERICAN NATIONAL STANDARD ZI 36.I. I986
43,7 Remoae Interlock Connector: (Class 3b or
Class 4). A Class 3b laser or laser system should be
provide.d with a remote interlock connector. A
Class 4 laser or laser system shall b€ provided with a
remote interlock connector.
The interlock connector facilitates electrical connections
to an emergency mastet disconnector interlock,
or to a room, entryway, floor, or area interlock, as
may be required for a Class 4 controlled area (see
4.3.10.2).
When the terminals of the connector are open circuited,
the accessible radiation shall not exceed the
appropriate MPE levels.
4.3,E Beam Stop or Attenuators (Class 3a,
Class 3b or Class 4), A Class 3a or a Class 3b laser
or laser system shoutd be provided with a permanently
attached tream stop or attenuator.
A Class 4 laser or laser system shall be provided with
a permanently attached beam stop or attenuator.
The beam stop or attenuator shall be capable of
preventing access to laser radiation in excess of the
appropriate MPE levet when the laser or laser system
output is not requircd.
There are many instances, such as during service,
when a temporary beam attenuator placed over the
beam aperture can reduce the level of accessible laser
radiation to levels below the applicable MPE level.
Such a practice can replace the requirements for laser
eye protection for some critical alignment procedures.
4.3.9 Laser Activation Warning Systems:
(Class 3b or Class 4). An alarm (for example, an
audible sound such as a bell or chime), a waming
light (visible through protective eyewear), or a verbal
"countdown"
command should be used with
Class 3b, and shall be used with Class 4 lasen or
laser systems during activation or startup.
Distinctive and clearly identifiable sounds which
arise from auxiliary equipment (such as a vacuum
pump or fan) and which are uniquely associated with
the emission of laser radiation are acceptable as an
audible waming.
4.3,9.1 Emissior Delay (Class 4). For Class 4
lasers or laser systems, the waming systcm shall be
activated a sufficient time prior to emission of laser
radiation to allow appropriate action to be taken to
avoid exposure to the laser radiation.
t4
4.3.10 Indoor Laser Controlled Area (Class 3b
or Class 4). A laser hazard analysis, including determination
of the NHZ, shall be effected by the LSO.
If the analysis determines that the classification associated
with the maximum level of accessible radiation
is Class 3b or Class 4, a laser conuolled area shall be
established and adequate control measurcs instituted
(see 4.3.10.1 or 4.3.10.2).
NOTE: The rcquirements for nonenclosed laseN or laser
systems inyolving the general public are detailed in 4.5.1.
4.3.10.1 Class 3b Laser Controlled Are:
(Class 3b). The Class 3b laser controlled area shall:
(l)Be posted with the appropriate waming
sign(s) (see 4,7), except as detailed in 4.5.1.10
(2) Be operated by qualified and authorized
personnel
(3) Be operated in a manner such that the path
is limited when the NHZ of the laser beam must exit
an indoor controlled area, particularly to the outdoors
under adverse atmospheric conditions, i.e., rain, fog,
snow, etc. See 4.3.1 I or 7.6
In addition to the above, a Class 3b contmlled arca
should:
(l) Be under the direct supervision of an individual
knowledgeable in laser safety
(2) Be so located that access to the area by
spectators is limited and requires approval, except as
detailed in 4.5
(3) Have any potentially hazardous beam terminated
in a beam stop of an appropriate material
(4) Have only diffuse reflective materials in or
near the beam path, where feasible
(5) Have personnel within the controlled arca
provided with the appropriate eye protection if there
is any possibility of viewing the direct or reflected
beams
(6) Have the laser secured such that the beam
path is above or below eye level of a person in any
standing or seated position, except as required for
medical use
(7) Have all windows, doorways, open ponals,
etc. from an indoor facility be either covered or restricted
in such a manner as to r€duce the transmitted
laser radiation to levels at or below the appmpriate
ocular MPE
(8) Requirc storage or disabling (for example,
removal of the k€y) of the laser or laser system when

not in use to prcvent unauthorized use
4.3.10.2 Class 4 Laser Controlled Ar€g
(Class 4). All personnel who regularly require entry
into a Class 4 laser controlled area shall be adequately
trained, provided with appropriate protecrive
equipment, and follow all applicable administrative
and procedural controls.
All Class 4 area/entryway safety controls shall be
designed to allow both rapid egrrss by laser person.
nel at all times and admiB,ance to the laser controlled
area under emergency conditions.
For emergency conditions therc shall be a clearly
marked
"Panic Button" (remote controlled connector
or equivalent device) available for deactivating the
laser or reducing the output to the appropdate MPE
levels.
The Class 4 laser controlled area shatl be designed to
fullill all items of 4.3.10.1, and in addition shall
incorporate one of the following altematives.
( I ) Non-Defeatable (non-override) Area,/Entryway
Safety Controls.
Non-defeatable safely latches, entryway or area inLerlocks
(e.g., electrical switches, pressure sensitive
floor mats, infrared or sonic detectors) shall be used
to deactivate the laser or reduce lhe output to the
appropriate MPE levels in the event of unexpected
entry into the laser controlled area. (See Figure 2a).
(2) Defeatable Area/Entryway Safery Controls.
Defeatable safety latches, entryway or area interlocks
shall be used if non-defeatable area/entryway safety
controls limit the intended use of the laser or laser
system. For example, during normal usage requiring
operation without interruption (e.9., long telm testing,
medical procedures, surgery), if it is clearly evident
that there is no oplical radiation hazard at the point of
entry, override of the safety controls shall be permitted
to allow access to authorized personnel provided
that they have been adequately trained and provided
with adequate personal protective equipment. (See
Figure 2a.)
(3) Procedural Area,/Entryway Safety Controls.
Where safety latches or interlocks are not feasible or
are inappropriate, for example during medical procedures,
surgery, etc., the followi[g shall apply (see
Fig.2b):
(a) All authorized personnel shall be adequately
trained and adequate personal protective
AMERICAN NATIONAL STANDARD 2I36.I -I986
equipment shall be provided upon enry
(b) A door, blocking barrier, screen, curtains,
etc. shall be used to block, scrcen or attenuate
the laser radiation at the entryway. The level of laser
radiation at the exterior of these devices shall not
exceed the applicable MPE, nor shall personnel
experience any exposure above the MPE immediately
upon entry
(c) From the entryway there shall be a
visible or audible signal indicating that the laser is
energized and operating at Class 4 levels. A lighted
laser waming sign or flashing light are two of the
appropriate methods to accomplish this requirement
4.3.11 Outdoor Control Measures (Class 3b or
Class 4). A Class 3b or Class 4 laser or laser system
used outdoors shall meet the following requircments:
(l) The LSO shall effect an analysis to establish
the NHZ if not available as pan of the
classification documentation nor fumished bv the
manufacturer
(2) Unprotected, ultrained and unauthorized
personnel shall be excluded from the beam path at all
points where the appropriate MPE is exceeded
(3) Appmpriate combinations of physical barriers,
screening, protective eye and body wear or
appropriate adminisirative controls shall be used if
personnel are permitted within the NHZ
(4) Directing the laser beam toward automobiles,
aircraft or other manned vehicles shall be prohibited
within the NHZ
(5) The laser beam path shall not be maintained
at or near personnel eye level without specific authorization
of the LSO
(6) The beam path shall be terminated where
possible
(7) When the laser is not being used, it shall be
disabled in a manner that prcvents unauthorized use
(8) Only qualified rmd authorized personnel
shall operate the laser or laser system
(9) The operation of Class 4 lasers or laser systems
during rain or snow-fall or in fog or dusty atmosphere
may produce hazardous reflections near the
beam. In such applications, the LSO shall effect an
evaluation of the need for, and specify the use of,
appropriate personal protective equipment
t5

AMERICAN NATIONAL STANDARD 2136,I.1986
4.3.12 Temporary Laser Controlled Area
(Embedded Class 3b or Class 4). In those conditions
where removal of panels or protective housings,
over-riding of protective housing interlocks, or entry
into the NHZ becomes necessary (such as for service),
and the accessible laser radiation exceeds th€
applicable MPE, a temporary laser controlled area
shall be devised for an embedded Class 3b or Class 4
laser or laser system.
Such an area, which by its nature will not have the
built-in proteclive features as defined for a laser controlled
area, shall provide all safety requirements for
all personnel, both within and without.
A notice sign (see 4.7.4.3) shall be posted outside the
temporary laser controlled area to wam of the potential
hazafi.
4.3.13 Remole Firing and Monitoring (Class 4).
Whenever appropriate and possible, Class 4 lasers or
laser systems should be monitored and fired from
remote positions. The remote console should also
include a laser activation waming system.
4.3.14 Equipment Lab€lsr (All Classes Except
Class l). All lasers or laser sysaems (except Class l)
shall have appropriate waming labels (see 4.7) with
the appropriate cautionary statement. The label shall
be affixed to a conspicuous place on the laser housing
or control panel. Such labels should be placed on
both the housing and the control panel if these are
separated by more than 2 meters.
NOTE: A Class 2a laser requires a label, but no symbol.
Additional wording for non-laser hazards may bc required
(see 7.4-61.
4,3.15 Area Posting Signs (Class 2, Class 3a,
Class 3b or Class 4). An area which contains a
Class 2 or Class 3a laser or laser system should be
posted with the appropriate sign as described in 4.7,
except as noted in 4.5. l.10.
An area which contains a Class 3b or Class 4 laser or
laser system shall be posted with the appropriate sign
as described in 4.7-
A notice sign, as described in 4.7, shall be posted outside
a temporary laser controlled area.
4.4 Administrative and Procedural Controls.
Administrative and procedural controls are methods
or instructions which specify rules, or work practices,
or both, which implement or supplement engineering
contrcis and which may specify thc use of personal
protcctive cquipmcnt. Unless otherwise specilied,
administrative and procedural controls shall apply
l6
only to Class 3b and Class 4 lasers or laser systems.
4.4.1 Standard Opersting Procedures: (Class
3b or Class 4). The LSO should require approved
written standard operating, maintenance and sewice
procedures (SOP's) for Class 3b lasers or laser systems.
The LSO shall require and approve written
SOP'S for Class 4 lasers or laser systems. These
written SOP's shall be maintained with the [aser
equipment for rcference by the op€rator. and maintenance
or service personnel.
4.4.2 Output Emission Limitations: (Class 3a,
Class 3b or Class 4). If, in the opinion of the LSO,
excessive power or radiant energy is accessible during
operation and maintenance, the LSO shall take
such action as required to rcduce the levels of accessible
power or radiant energy to that which is commensurate
with the required applicaaion.
4.4.3 Education and Training: (Class 2, Class
3a, Class 3b or Class 4). Education and training
shall be provided for operators, maintenance or service
personnel for Class 3a, Class 3b or Class 4 lasers
or laser systems, Education and raining should be
providcd for opcratoni. maintenance or service personnel
for Class 2 lasers or laser systems. The level
of training shall be commensurate with the level of
potential hazard (see Section 5 and Appendix D).
4.4.4 Authorized Personnel (Class 3b or Class
4). Class 3b or Class 4 lasers or laser systems shall
be operated, maintained or serviced only by authorized
personnel. l-asers or laser systems with embedded
Cla.ss 3b or Class 4 lasers shall be maintained or
serviced only by authorized personnel if such procedures
would permit access to levels which exceed
the appropriate MPE (see Section 5).
4.4.5 Alignment Procedures (Class 2, Class 3a'
Class 3b or Class 4). Alignment of laser optical systems
(mirrors, lenses, beam deflectors, etc.) shatl be
performed in such a manner that the primary beam, or
a specular or diffuse reflection of a beam, does not
expose the eye to a level above the applicable MPE.
Written procedures outlining alignment methods
should be approved for Class 3b and shall be
approved for Class 4 lasers or laser systems. The use
of low power (Class I or Class 2) visible lasers for
path simulation of higher power lasers is recommended
for alignment of higher power Class 3b or
Class 4 visible or invisible lasers and laser systems.
Experience has shown that a significant ocular hazard
muy exist during olignment procedures.

4.4,6 Eye Protection (Class 3b or Class 4). Eye
protection devices which are speciRcally designed for
protection against radiation from Class 3b lasers or
laser systems should be administratively required and
their use enforced when engineering or other procedural
and admiui$trative controls are inadequate to
eliminate potential exposure in excess of the appticable
MPE (see 4.6).
Eye protection devic€s which are specifically
designed for protection against radiation from Class 4
lasers or laser systems shall be administratively
required and their use enforced when engineering or
other procedural and administrative controls are
inadequate to eliminate potential exposure in excess
of the applicable MPE (see 4.6).
When long-term exposure to visible lasers is not
intended, the applicable MPE used to establish the
optical density requircment for eye protection may be
based on a 0.25 second exposure (see 8-2).
When viewing an extended source or the diffuse
reflection of the beam from a Class 3b or Class 4
la,ser or laser system where intermediate viewing time
is intended, e.g., optical alignment procedures, the
applicable MPE should be based upon the maximum
viewing time anticipated during any given 8 hour
period. For example, a maximum viewing time of
600 seconds is applicable for most alignment procedures
when viewing a diffusely reflecting target.
If the extended source criteria (8.3) is not applicable
due to a small beam size, then the exposure at the
comea from a diffuse reflector may be estimated
using the inverse square law relationship and the
intrabeam MPE criteria shall apply. See B.4.4.
4.4.7 Spectators (Class 3b or Class 4). Spectators
should not be permitted within a laser controlled
area (see4.3.10 and 4.3.11) which contains a
Class 3b laser or laser system and spectators shall not
be permitted within a laser controlled area which contains
a Class 4 laser or laser system unless:
(l) appropriate supervisory approval has been
obtained
(2) the degree of hazard and avoidance procedure
has been explained
(3) appropriate protective measurcs are taken
Laser demonstrations involving the general public
shall be govemed by the requirements of 4.5.
4.4.8 Seryice Personnel (All Classes). Personnel
who require access to Class 3b or Class 4 lasers or
laser systems contained within a protecdve housing
AMERICAN NATIONAL STANDARD 2I36.I.I986
or protected area enclosure for the Purpose of service
shall comply with the appropriate control measures of
the enclosed or embedded laser or laser system. The
service personnel shall have the education and training
commensurate with the class of the laser or laser
system contained within the pmtective housing.
4.5 Special Considerations
4.5.1 Laser Demonstrations Involving the G€neral
Public. The following special control measures
shall be employed for those situations where lasers or
laser systems are used for demonstration, anistic
display, entertainment or other related uses where the
intended viewing group is the general public.
Such demonstrations can be, but are not timited to,
trade show demonstrations, artistic light performances,
planetarium laser shows, discotheque lighting,
stage tighting effects and similar special lighting
effects that use lasers or laser systems emitting in the
visible wavelength range (0.4 to 0.7 pm).
For the purposes of this section, the applicable MPE
may be detemined by using the classilication duration
defined as the total combined operational time of
the laser during the performance or demonshation
within any single period of 3 x lOa seconds.
4.5.1.1 Operational Requir€ments - Gen'
erat. Only Class I laser or laser systems shall be
used for general public demonstration, display' or
entertainment in unsupervised areas without additional
rcquirements,
lf unsupervised, the use of Class 2 and Class 3a lasers
or laser systeDs shall be limited to installations
which prcvent access to the direct or specularly
reflected beams or where the accessible radiation is
maintained at the distance requirements specified in
4.5.1.6.
The use of Class 3b or Class 4 lasers or laser systems
shall be permitted only under the following conditions:
(l) When the laser operation is under the control
of an experienced, trained operator
(2) When the laser is operated in a superyised
laser installation as specified in 4.5.1.7
(3) When the laser is operaaed in an unsupervised
laser installation provided: (a) the LSO has
assured that appropriate controls are incorporated
which provide for an equivalent degree of protection
to the general public: (b) a designated person, present
at all times at the show or display, is responsible for
t7

AMERICAN NATIONAL STANDARD 2I36.I-I986
the immediate termination of the laser equipment in
the event of equipment malfunction, audience unruliness,
or other unsafe conditions.
For training of operators see Section 5.
4.5.1.2 Invisible Laser Emission Limitations.
The general public shall not be exposed nor have
access to laser radiation emission at wavelengths outside
the visible range (0.4 to 0.7 pm) at levels
exceeding the applicable MPE levels under any possible
conditions of operation.
4,5.1.3 Optical Radlatlon Limlts for the General
Public. Laser radiation in the location where the
general public is normally allowed shall not exceed
the applicable MPE levels during operation. hser
radiation to be considered shall include reflections
from all possible surfaces and scattering materials.
4.5.1.4 Operator and Performers. Alt operators,
performers and employees shall be able lo perform
their required functions without the need for
exposure to laser radiation levels in excess of the
applicable MPE level.
4,5.1.5 Scanning Devices. Scanning devices,
including rotating minored balls, shall incorporate a
means to prevent laser emission if scan failure or
other failure resulting in a change in either scan velocity
or amplitude would result in failure to fulfill the
criteria given in 4.5.1.3 and 4.5.1.4.
4.5.1.6 Unsupervised Installaaions - Distanc€
R€quirements. If a laser demonstration using
a Class 2. Class 3a, Class 3b or Class 4 laser does not
operate at all limes under the direct supervision or
conhol of an experienced, trained operator, the laser
radiation levels to which access can be gained shall
be limited by baniers, windows, or other means so as
not to exceed the limits of the applicable MPE. This
limitation applies at any point less than 6 m above
any surface upon which a penon in the general public
is permitted to stand and to any point less than 2.5 m
in lateral separation from any position where a person
in the general public is permitted to be present du ng
the performance or display. See Figures 2c, 2d and
2e.
4.5.1.7 Supervis€d Laser Installations. Laser
demonstrations which do not meet the criteria stated
in 4.5.1.6 shall be operated at all times under the
direct supervision or conrol of an experienced,
trained operator who shall maintain constant surveillance
of the laser display and terminate the laser
emission in the event of equipment malfunction.
audience unruliness or other unsafe conditions.
18
The operator shall have visual access to the entire
area of concem. lf obstacles or size preclude visual
access by the operator, then multiple obsewers shall
be used, with a communication link to the operator,
In such supervised installations accessible laser radiation
shall be limited by baniers, windows or other
means so as to not exceed the applicable MPE (see
4.5.1) at any point unless the following requirements
arc mer:
(l ) The accessible laser radiation is maintained
a minimum distance of 3.0 m above any sudace upon
which the general public would be able to stand during
a performance. See Figure 2d.
(2) The accessible laser radiation is maintained
a minimum distance of 2.5 m in lateral separation
from any position where the general public is permitted
to be prcsent during the performance or demonstration.
See Figure 2e.
As a general practice, the largest practical venical
and lateral separation distances should be employed
wherever possible. However, if specific physical limitations
of the space in which the lasers are to be used
preclude compliance with the required minimum
separations specified in (l) and (2), shorter separation
distances may be utilized, provided that the LSO
assures that altemative measurBs are established
which assure an equivalent degree of protection to the
general public.
4.5.1.8Beam Termination Requirements.
All laser demonshation syslems shall be provided
with a rcadily accessible means to effect immediate
termination of the laser radiation. lf the demonstration
does not require continuous supervision or
operator control during its operation, there must be a
designated person at all times at the show or display
who is responsible for the immediate termination of
the laser radiation in the event of equipment malfunction,
audience unruliness or other unsafe cond.itions.
45,1.9 Maximum Power Limitations. The
maximum output power of the laser shall be limited
to the level required to pmduce the desired and
intended effect within the limitations outlined in
4.5.1.1 through 4.5.1.8.
4.5.1,10 Posting of Warning Signs and
l-ogm. If the laser installation fulfills all requirements
as detailed in 4.5.1.1 through 4.5.1.9 - or as
altematively provided by the LSO (see, for example,
4.5.1.7\ - then posting of area waming signs shall
not be required.

4.5.1.11 Federal, Slste, or Local Require.
ments, The lsscr operstor snd/or LSO responsible
for producing the laser demonsfation should determine
that any applicable federal, state, or local
requirements are satisfr ed.
4J,2 Laser Optical Fiber Transmission System.
Laser transmission systems which employ optical
cables shall be considered enclosed systems with
the optical cable forming part of the enclosure. If
disconnection of a connector results in accessible
radiation being reduced to below the applicable MPE
by engineering conhols, connection or disconnection
may take place in an uncontrolled area and no other
control measures are required. When the system provides
access to laser radiation above the applicable
MPE via a connector, lhe conditions given in 4.5.2.1
or 4.5.2.2, or for optical communication systems as
specifled in the American National Standard for the
Safe Use of Optical Fiber Communication Systems
Utilizing Laser Diode and LED Sources, ANSI
2136.2, shalt apply.
4.5.2.1 Connection or disconnection during
operation shall take place in an appropriate laser controlled
area, in accordance with the requirements of
4.3.12, ifthe MPE is exceeded.
4.5.2.2 Connection or disconnection during
maintenance, modification, or service shall take place
in a temporary laser conuolled area, in accordance
with 4.3.12 if the MPE is exceeded. When the connection
or disconnection is made by means of a connector,
other than one within a secured enclosure,
such a connector shall be disconnectable onlv bv the
use of a tool.
When the connection or disconnection is made within
a secured enclosure, no tool for connector disconnection
shall be required, but a waming sign appropriate
to the class of laser or laser system shall be visible
when the enclosure is open.
4.6 Personal Protective Equipment
4.6.1 General. Enclosure of the laser equipment
or beam path is the prefened method of control, since
the enclosure will isolate or minimize the hazard.
When other control measures do not provide adequate
means to prevent access to direct or reflected beams
at levels above the MPE, it may be necessary to use
p€rsonal protective equipment. It should be noted
that personal protective equipment may have serious
limitations when used as the only contol measure
with higher-power Class 4 lasers or laser systems; the
protective equipment may not adequately reduce or
AMERICAN NATIONAL STANDARDZI36.I-I986
eliminate the hazard.
4,6.2 Prolective Eyewear (Class 3b or Class 4)
4.6,2.1 Class 3b Laser. Protective eyewear
should be wom whenever operational conditions may
result in a potential eye hazard.
4.6,2,2 Class 4 Laser. Protective eyewear
shall be wom whenever operational conditions may
result in a potential eye hazard.
4,6.2.3 Eyewear for Proteciion Against
Other Agents. Physical and chemical hazards to the
eye can be rcduced by the use of face shields, goggles
and similar protective devices. Consult American
National Standard Practice for Occupational and Educational
Eye and Face Protection, ANSI 287.1-1979
(or latest revision thereo0,
4,6.2.4 Factors in D€t€rmining Appropriate
Eyewear. The following factors shall be considercd
in determining the appmpriate protective ey€wear to
be used:
( I ) Wavelength of laser output
(2) Potential for multiwavelength operation
(3) Radiant exposure or iradiance
(4) Maximum permissible exposure (MPE)
(see Section 8, Criteria for Exposure of the Eye and
Skin)
(5) Optical density of eyewear at laser output
wavelength
(6) Visible light hansmission requirement
(7) Peripheral vision r€quirement
(8) Radiant exposure or irradiance and the
corresponding time factors at which laser. safety
eyewear damage (penetration) occurs, including transient
bleaching
(9) Need for prescription glasses
(10) Comfon and fit
(l l) D€gradation of absofting media, such as
photobleaching
(12) Strength of materials (resistance to shock)
(13) Capability of the fmnt surface to produce
a specular reflection
4.6.2.5 OptlcalDensity
4.6.2.5.1 Specification of Opaical Density'
D1. The optical density (attenuation), D1, of laser
piotective eyewear at a specific wavelength shall be
19

AMERICAN NATIONAL STANDARD 2I36. I. I986
specified. Many lasers radiate at more than one
wavelength; thus eyewear designed to have an adequate
l)1 for a particular wavelength could have a
completely inadequate Dt at another wavelength
radiated by the same laser. This problem may
become panicularly serious with lasers that are tunable
over broad wavelength bands. In such cases,
altemative methods of eye protection, such as indir€ct
viewing, may be more appropriate (e.9., image converte$.
closed circuit TV).
If the potenlial eye exposure is given by H/,, the optical
density, DI, required of protective eyewear to
reduce this exposure to the MPE is given by
H
D1= log;s
lutfu = - log'ofr
where Ho is expressed in the same units as the
appropriate MPE and Tt is the transmittance of the
filter at the specific wavelength (see Section 8).
NOTEi When thc laser beam ir smaller than the limiting
aperture (L,{ ), the value of H/, is determined by averaging
the beam energy over the limiting aperture (7 mm for the
0.4 to 1,4 Um region). This is required because the MPE
value has been established (normalized) relative to the limiting
aperture area. Use of the beam diamercr (o) to evaluate
F/p for cases where a

using Class 4 lasers,
4.6.4 Other Personnel Protective Equipment.
Respirators and hearing protection may be required
whenever engineering contlols cannot provide protection
from a harmful ancillary envimnment (see 7.1).
4.7 Warning Signs and Labels
4.7.1 Design of Signs. Sign dimensions, letter
size and color. etc.. shall be in accordance with
American Nationel Standard Specification for
Accident Prevention Signs, ANSI Z35-l-1972 (or the
latest revision thereof). Figures la and lb show sample
signs for Class 2, Class 3a, Class 3b and Class 4
lasers or laser systems.
4.7.2 Symbols. The laser hazard symbol shall be
a sunburst panem consisting of two sets of radial
spokes of different lengths and one long spoke, radiating
from a common center.
The color, dimensions, and location of the symbol
within lhe sign shall be as specified in the American
National Standard Specification for Accident Prevention
Signs, ANSI 235.1- 1972, (or the latest revision
thereoO.
NOTE: Classification labeling in accordance with the
Federal Laser Product Performance Standard may be used
to satisfy the labeling requirements in this section.
4.7,3 Signal Words
4.7.3.1 The signal word "Caution" shall be
used with all signs and labels associated with Class 2
lasers and laser syslem.s and all Class 3a lasers and
laser systems that do not exceed the appropriate MPE
for irradiance (see Figure ta). The signal word
"Danger" shall be used with all signs and labels
associated with all other Class 3a, and all Class 3b
and Class 4 lasen and laser systems (see Figurc lb).
4.7,3.2 A Class 2a laser or laser system shall
have a label affixed which instructs: "Avoid Long-
Term Viewing of Direct Laser Radiation". This
label need not bear the waming symbol (see 4.7.2) or
signal words but must be clearly visible during operation
and bear the designation "Class 2a Laser".
4.7.3.3 The word "Radiation" on signs and
labels may be replaced by the word "Light"
for
lasers operating in the visible mnge at wavelengths
greater than 0.4 pm and equal to or less than 0.7 pm.
For lasers operating outside of this visible range th€
word "invisible" shall be placed prior to the word
"radiation".
AMERICAN NATIONAL STANDARD ZI 36. I.I986
4.7.4 Inclusion of Pertinent Information. Signs
and labels shall conform to the following
specifications.
4.7.4.1 The rypropriate signal word (Caution or
Danger) shall be located in the upper panel.
4.7.4.2 Adequate spac€ shall be left on all signs
and labels to allow the inclusion of pertinent informanon.
Such information may be included during the printing
of the sign or label or may be handwritten in a legible
manner, and shall include the following:
(l) At position I above the tail of the sunburst,
special precautionary instructions or protective
actions required by the reader such as:
(a) For Class 2 and Class 3a lasers and
laser systems wherc the accessible irradiance does not
exceed the appropriate MPE based upon a 0.25
second exposure (see 3.2.3.3.3)
"Laser Radiation -
Do Not Stare into Beam or View with Optical Instruments"
(b) For all other Class 3a las€rs and laser
systems, "l-aser Radiation - Avoid Direct Eye
Exposure"
(c) For all Class 3b lasers and laser systems,
"Laser Radiation - Avoid Direct Exposure to
Beam"
(d) For Class 4 lasers and laser systems,
"Laser
Radiation - Avoid Eye or Skin Exposure to
Direct or Scattered Radiation"
(2) At position I above the tail of the sunburst,
special precautionary instructions or protecliv€ action
such as: Invisible Laser Radiation; Knock Before
Entering; Do Not Enler When Light is On; Restricted
Arcai etc,
(3) At posilion 2 below the tail of the sunbuIst,
type of laser (Ruby, Helium-Neon, etc.), or the emitted
wavelength, pulse duration (if appropriate), and
maxtmum output
(4) At position 3, the class of the laser or laser
sysrem
4.7,4.3 Temporary Laser Controlled Area
Signs: lClass 3b or Class 4). A notice sign (see
Figure lc) shall be posted outside a temporary laser
controlled area (see4.3.12) for example, during
periods of service. When a temporary laser controlled
area is created, the area outside the temporary
area remains Class l, while the area within is either
Class 3b or class 4 and the appropriate danger
?l

AMERICAN NATIONAL STANDARD 2136,1- I986
waming is required. (See Figure lb.)
4.7.4.4 Display Signs and Labels, All signs
and labels shall be conspicuously displayed in locations
where they best will serve to wam onlookers.
4.7.4.5 Existing Signs and Labels. Signs and
labels prepared in accordance with previous revisions
of this standard are considered to fulfill the recuirement
of the standard.
4.E Service and Repair of Laser Systerns. Following
any service or repair which may affect the output
power or operating characteristics of a laser or laser
system so as to make it potentially more hazardous,
the LSO shall ascenain whether any changes are
required in control measures.
4.9 Modiffcation of Laser Systems. Whenever deliberate
modifications are made which could change a
laser or laser system's class and affect its output
power or operating characteristics so as to make it
potentially more hazardous, the LSO shall ascenain
whether any changes and control mgasures are
required.
5. Laser Safety and Training Programs
5.1 Organization. The management (employer)
shall establish and maintain an adequate program for
the control of laser hazards. Safety and training progmms
shall be required for Class 3a, Class 3b or
Class 4 lasers and laser systems. Safety and training
programs should be required for Class 2 lasers and
laser systems. Safety and training programs are not
required for Class I or Class 2a lasers and la,ser systems,
The program shall include provisions for the
following:
(1) Delegarion of authority and responsibility to the
LSO for the monitoring and enforcement of hazard
evaluation and control of laser hazards. Depending
on the extent and number of laser operations, the
position of LSO may or may not be a full-time
assignment. Where the number and diversity of laser
operations warrants, an nssociated Safety Committee
may be formed and utilized. When there is normally
no requirement for an LSO, such as the operation of
Class I or Class 2 lasers and laser systems which
contain lasers with a higher classification, the designation
of LSO for temporary periods of access for
servicing, training, etc, may be the responsibility of
the organization requiring access, such as a service
22
organization. However, there shall be a designated
LSO for all circumstances of operations of a laser or
laser system above Class 2. Specific minimum duties
of the LSO are detailed in l3.2
(2) Education of authorized penonnel (LSOs, operators,
sewice personnel and others) in the assessment
and control of laser hazards. This may be accomplished
thmugh training programs
(3) Application of adequate protective measures for
the control of laser hazards as required in Section 4
(4) Incident investigation, including reporting of
alleged accidents, and preparation of action plans for
the futur€ prevention of accidents following a known
or susp€cted incident. (See reference [7] in D7 for
Federal reporting requirements.)
(5) Provide an appropriate rnedical surveillance pmgram
in accordance with Section 6
A guide for the organization of a laser safety proglam
is outlined in Appendix D.
5.2 Education. The management shall provide
training to the LSO on the potential hazards (including
bioeffects), control m€asures, applicable standards,
medical surveillance (if applicable) and other
pertinent information pertaining to laser safety or provide
to the LSO adequate consultive services. The
training shall be commensurate to at least the highest
class of laser under the jurisdiction of the LSO.
Safety raining program(s) shall be provided to the
users of Class 3a, Class 3b or Class 4 lasers and laser
systemsr and should be provided to the users of
Class 2 lasers and laser systems. Users shall include
operators, technicians, engineers, maintenance and
service personnel, etc., working with lasers. The
training shall ensure that the users are knowledgeable
of the potential hazards and the control mealurcs for
laser equipment they may have occasion to use.
Where applicable, training shall include elecrical
safety and cardiopulmonary rcsuscitation (CPR).
(See 7.4.7.)
A guide for the organization of a training program is
outlined in D6.
5.3 lmplementation. The management shall provide
adequate supewision, personnel training, facilities,
equipmeDt fid supplies to control potential
hazands of laser and laser systems.

6. MedicalSurveillance
6.1 General. The radonale for medical surveillance
requirements for personnel working in a laser
enyironment and specific information of value to examining
or attending physicians are included in
Appendix E. Medical surveillance requirements have
been limited to those that are clearly indicated, based
on known risks of particular kinds of laser radiation.
Medical surveillance is not required for personnel
using Class l, Class 2, Class 2a or Class 3a lasers and
laser systems as defined in 3.3.3.2 and is required for
Class 3b and Class 4lasers and laser systems. Some
employers may wisb to provide their employees with
additional examinations for medical-legal reasons, to
conform with established principles of what constitutes
a thorough ophthalmologic or dermatologic
examination, or as pan of a planned epidemiologic
study. Further information is provided in
Appendix E.
6.2 Personnel Categories. Each emptoyee's
category shall be determined by the LSO in charge of
the installation involved. The indiyiduals who should
be under laser medical surveillance are defined in
6.2.1 and 6.2.7.
6,2.1 Incidental Personnel. Incidental personnel
are those whose work makes it possible (but unlikely)
that they will be exposed to laser energy sufficient to
damage their eyes or skin, e.9., custodial, military
personnel on maneuvers, clerical, and supervisory
personnel not working directly with laser devices.
6.2.7 Lasel Personnel. l,aser personnel are those
who work routinely in laser environments. These
individuals are ordinarily fully protected by engineering
controls or administrative procedures, or both.
6.3 Ceneral Procedures
6.3.1 Incidental personnel shall have an eye examination
for visual acuity (see Appendix E for further
details).
6.3.2 t aser personnel shall be subject to the following
baseline eye examination:
Ocular history (E2.2.1). If the ocular history shows
no probfems and visual acuity (E2.2.2) is found to be
2OIZO (616 in each eye for far, and Jaeger l+ for near)
with corrections (whether wom or not), central visual
fields (82.2.3) and contrast sensitivity (E2.2.4) are
normal, no further examination is required. Laser
workers with medical conditions noted in E2.2.1
AMERICAN NATIONAL STANDARD ZI36.I-I986
should be evaluated carefully with respect to the
potential forchronic exposure to laser radiation, Any
deviations from acceptable performance will rcquire
an identification of the underlying pathology either
by a funduscopic examination (E2.2.5), or other tests
as determined appropriate by the responsible medical
examiner.
6.4 Frequency of Medical Examinations. For both
incidental and laser personnel, required examinations
shall be performed prior to panicipation in laser
work. Following any suspected laser injury, the pertinena
required examinations will be repeated, in
addition to whatever other examinations may b€
desired by the altending physician. Periodic examinations
are not required.
7. SpecialConsiderations
7.1 Industrial Hygiene Considerations. In many
laser applications industrial hygiene aspects may
require consideration. Associated hazards shall be
evaluated and appropriate conhol measures taken.
Some examples of these aspects are hazards associated
with compressed gas, fumes, cryogenic materials,
toxic and carcinogenic materials, noise and ionizing
radiation. Adequate local exhaust ventilation
shall be installed to reduce po@ntialty hazardous
fumes and vapors produced by laser welding, cutting
and other laser target interactions to levels b€low the
appropriate threshold limit values. Appendix F provides
reference material to aid in the control of such
hazards.
7,2 Explosion Hazards. High-pressure arc lamps
and filament lamps in laser equipment shall be
enclosed in housings which can withstand the maximum
explosive pressures resulting from lamp disintegration.
The laser target and elements of the optical
train which may shaltcr during lascr operalion shall
also be enclosed or equivalently protected to prevent
injury to operators and observers.
7.3 Optical Radiation Hazards - (Other than
Laser Beam Hazards). Ultraviolet radiation emi ed
from laser discharge tube$ and pumping lamps (i.e.,
not part of the primary laser beam) shall be suitably
shielded so that personnel exposures are maintained
within the threshold limit values specified by the
American Conference of Govemmental lndustrial
Hygienists.

AMERICAN NATIONAL STANDARD 2136,I - I986
Studies have shown that plasma emissions created
during a laser-welding process may have sufficient
ult.aviolet and/or blue light content (0.2 to 0.55 pm)
to raise concem for operators viewing a laser-welding
proc€ss on a long-term basis without additional protection
for the plasma emission.
7.4 El€ctrical Harards. Electrocutions have
occurred to a number of individuals touble-shooting
or sewicing laser equipment. Generally the individual
was working alone or other personnel working
nearby did not know how to administer Cardiopulmonary
Resuscitation (CPR, see 7.4.7). The importance
of adequate training, and the use of the "buddy
system" when working around high voltage laser
power supplies cannot be overstressed. Protective
electrical circuit design is also important. The laser
resonator and electro-optical elements should be
designed so that no exposed metallic element is
above ground potential.
7.4.1 Installation, The intended application of
the laser equipment determines the method of electrical
installation and connection to the power supply
circuit (for example, conduit vs flexible cord). All
equipment shall be installed as specified in the
National Electrical Code. Such installed equipment
is acceptable to the U.S. Department of Labor, Occupational
Safety and Health Administration, if
accepted, certified, listed, labeled. or otherwise deter'
mined safe by a qualitied testing laboratory, such as,
but not limited to, Underwriters Laboratories Inc. and
Factory Mutual Corporation.
7.4.2 Shock Hazard. Live parts of circuits and
components with peak open-circuit potentials over
42.5 volts are considered hazardous, unless limited to
less than 0.5 mA. Such circuits require positive protection
against contact. For equipment intended for
general use, interlock switches (and capacitor bleeder
resistors, if applicable) or their equivalent shall be
installed to remove the voltage from accessible live
parts to permit servicing operation. Bleeder resisron
shall be of such size and rating as to carry the capacitor
discharge current without bumout or mechanical
injury. Circuits and components with peak opencircuit
potentials of 2500 volts or more shall be adequately
covered or enclosed if an appreciable capacitance
is associated with the circuits.
If servicing of equipment requires entrance into an
interlocked enclosure within 24-hours of the presence
of high voltage within the unit, a solid metal grounding
rod shall be utilized to ensure discharge of highvoliage
capacitors. The grounding rod shall be firmly
attached to ground prior to contact with the potentially
live point. A resistor grounding rod (for example,
a large-wattage ceramic resistor) may be used
pfior to applicadon of the solid conductor grounding
rod to protect circuit components from overly rapid
discharge, but shall not be used as a replacement'
7.4.3 Grounding, The frames, enclosures and
other accessible nontunenttarrying metallic parts
of laser equipment shall be grounded. Grounding
shall be accomplished by providing a rcliable, con'
tinuous metallic connection between the part or parts
to be grounded and the grounding conductor of the
power wiring system.
7.4,4 Electrical Fire Hazards' Components in
electrical circuits shalt be evaluated with r€spect to
6re hazards. Enclosures, barriers or baffles of nonmetallic
material shall comply with "Polymeric
Materials for use in Electric Equipment," Underwriters
Laboratories Standard, UL 746C.
7.4.5 Electrical Hazards from Explosion. Gas
laser tubes and llash lamps shall be supponed to
ensure that their terminals cannot make any contact
which will result in a shock or fire hazard in the event
of a tube or lamp failure. Components such as electrolytic
capacitors may explode if subjected to voltages
higher than their ratings, with the result that
ejected metal may bridge live electrical parts' Such
capacitors shall be tesbd to make cenain that they
can withstand the highest probable potentials should
other circuit componenls fail, unless lhe capacitors
are adequately contained so as not to crcate a hazard.
7.4.6 Marking. The user shall ensure that each
laser is permanently marked with its Primary electrical
rating in volts, frequency, and watts or amperes.
If the laser is intended for use by the public or by p€r'
sonnel untrained in laser safety, and is provided with
clectrical safety interlocks, waming notices instructing
the user not to defeat the interlock should be
applied to the device immediately adjacent thereto.
7.4,7 Cardiopulmonary Resuscitation (CPR).
Laser service personnel, research personnel and their
assistants working with high voltages shall be trained
in CPR. Periodic refresher courses shall be provided
by the employer.
7,5 Flammability of Laser Beam Enclosures.
Enclosure of Class 4 laser beams can result in potential
fire hazards if suitable enclosure materials are
likely to be exposed to iffadiances exceeding
lOWcm2 or total beam powers exceeding 0.5 W.
Plastic materials and paper producb are not

precluded, but their use and potential for direct expo-
$ure should be considercd. Flame resictant materials
should be encouraged.
7.6 Laser Operation in Outdoor Environments
7.6.1 Use of Lasers in Navigable Airspace, The
Federal Aviation Administration (FAA) is responsible
for regulating the use and efficient utilization of
navigable airspace to ensurc the safety of aircraft and
the protection of people and propefly on the ground.
Laser experiments or programs that will involve the
use of navigable airspace should be coordinated with
the FAA (Washington, DC 20590, or any FAA
regional office) in the planning stages to ensure
pmper control of any attendant hazard to airbome
personnel or equipment.
7.6.2 Laser Beam Attenuation. The effects of
attenuation on a laser beam traveling through a
homogeneous but lossy medium can be trested at
visible wavelengths by using an exponential attenuation
coefficient. (See B.4.) For propagation at longer
wavelengths, individual lines must be separately
determined, panicularly at wavelengths where the
effects of waier vapor become important.
7.6.3 Scintillation, Scintillation arises from local
variations in the refractive index of the medium
through which a laser beam is propagated. It causes
random pointing, spreading, blurring and energy
redistribution of a beam. A "worst-case" analysis
shall be used in evaluating the potential ocular hazard
from such scintillation €ffects.
NOTE: References useful for the special considerations
covered in 7-l through 7.6 may be found in Appendix F.
8. Criteria for Exposure ofthe Eye and Skin
Maximum prermissibte exposure (MPE) values are
below known hazardous levels. Levels at the MPE
values given may be uncomfonable to view or feel
upon the skin. Thus, it is good practice to maintain
exposure levels as far below the MPE values as is
practicable.
When a laser emits radiation at several widely different
wayelengths, or where pulses are superimposed
on a cw background, computation of the MPE is
complex. Exposures from several wavelengths in the
same time domain are additive on a proportional
basis of specral effectiveness with due allowance for
all correction factors. The simultaneous exposure to
pulses and cw radiation is not strictly additive (there
AMERICAN NATIONAL STANDARD 2I36.1-I986
may be synergism) and caution should be used in
these situations until more data arc available.
The limiting aperture shall be used for measurements
and calculations with all MPE values. The limiting
aperture is the maximum circular area over which
irradiance and radiant exposure can be averaged. See
Table 9 and Fig. 13 for proper application of this
aPenurc.
In the tabulations for MPE, values for irradiance can
be obtained by dividing the radiant exposure by the
time, t, in seconds, and values for radiant exposure
can be obtained by multiplying the irradiance by r in
seconds.
NOTE: Exposure limits for pulse duralions less than I ns
are Dot provided !1 lhc prescnt time becausc of a laqk of
biological data. However, IEC Srandard 825 (1984) suggests
limiting peak inadianc€s to the exposure limit applicable
to nanosecond pulses.
Appendix G provides reference material on this subject.
8.1 Intrabeam Viewing and Extend€d Source
Ocular Exposures. For the purposes of this standard,
sources such as laser arrays, diodes and diffuse
reflecting surfaces are considered to be extended
sources if their angular subtense (apparent visual
angle) is equal to or greater than cr,;n as specifled in
Fig.3. For all other laseni, including as those wilh
collimated beams which produce a small (nearly
diffractionlimited) retinal imag€ and also point
sources, intrabeam viewing criteria applies. In this
category the angular subtense is less than o-in.
Sources such as laser arrays, multiple diodes, or multiple
diffuse reflecting surfaces are treated as in[abeam
viewing cases for any of the separate images
whose angular subtense is less than (Iln6. Any
sources whose centers are separated by an angle less
than ohrin are treated as extended sources. See 9.2 for
sources between 0.4 pm and L4 Um.
Appropriate MPES are associated with each type of
source, For intrabeam viewing criteria see 8.2t for
extended-source viewing criteria see 8.3.
NOTE: The angular subtense is not the beam divergence of
the source. It is the apparent visual angle as calculated
from the source size and distance from the eye. The limiting
angular subtense is that apparent visual angle which
divides intrabeam viewing from extended-source viewing.
See B-3-2.
8.2 MPE for Inarabeam Viewing. The single pulse
or single exposure MPE values for intrabeam viewing
are given in Table 5. ln order to apply these MPE
ZJ

AMERICAN NATIONAL STANDARD 2I36.I.I986
values, the information specified in 8.2.1 and 8.2.2 is
required. (See 8.5 for special qualilications and use;
see also Figs. 4,5,6 and 10.)
8.2,1 Wavelength. The wavelength must be
specified to establish which specral region is applicable.
The MPEs in Table 5 arc arranged in broad
wavelength regions and by specific wavelength
expressed in micrometers. Fot multiple wavelength
laser emissions, the MPE must first be determined for
each wavelength separately. In the ultraviolet rtgion,
special considerations may apply for multiple exposures
(see 8.2.2.1).
8.2,2 Exposure Duration. For a single-pulse
laser, the exposure duration is equal to the pulse duration,
r, defined at its half-power points. For a cw visible
(0.4 to 0.7 pm) laser, the exposurc duration is the
maximum time of anticipated direct exposure, fm"*,
If purposeful staring into the beam is not intended or
anticipat€d, then the aversion response time, 0,25 s,
may be used.
For non-visible wavelengths (less than 0.4 pm or
greater than 0.7 Fm), the cw exposur€ duration is the
maximum time of anticipated direct exposute, I.",.
For the hazard evaluation of retinal exposures in the
near-infrared (0.7 to 1.4 Fm), a maximum exposure
duration of l0 s provides an adequate hazard criterion
for either unintended or purposeful staring condi
tions. In this case, eye movements will provide a
nalural exposure limitation eliminating the need for
exposure durations greater than l0s, except for
unusual conditions. In special applications, such as
medical instrumentation, even longer exposure durations
may apply.
For rep€titively pulsed lasers, the total exposure duration,
I, of the train of pulses must be determined.
This duration is determined in lhe same manner as is
used for cw laser exposures. The method for determining
the MPEs for repetitively pulsed laser exposures
is given in 8.2.2.1 and 8.2.2.2. Forpulse widths
less than I ns, see Note in Section 8.
8.2,2.lRepeated Exposures, Ultraviolet
(0.315 to 0.4 pm) - Special Considerations. For
repeated exposures, the exposure dose is additive
over a 24-hour period, regardless of the repetition
rate. The MPE for any 24-hour period should be
reduced by a factor of 2.5 times relative to the
single-pulse MPE if exposures on succeeding days
are expected.
26
E.2.2,2 Repeated Exposures, Visible (0,4 to
0.7 pm) and Infrared (> 0.7 pm), Bolh scanned cw
lasers and repetitively pulsed lasers can produce
repetitively pulsed exposur€ conditions. The MPE
per pulse for repetitively pulsed intrabeam viewing is
a-rl4 times the MPE for a single pulse cxposure
where r is the number of pulses found from the product
of the prf and the exposure duration (f) as
defined in 8.2.2. (See Figure 12 for a graphical
repr€sentation of n-t14.) This MPE applies to all
wavelengths greater than 0.7 pm (thermal injury).
For wavelengths less than 0.7 pm, the MPE as calculated
on the basis of n-rla also must not exceed the
MPE calculated for nt seconds when nt is grcater than
l0 s.
For pulse repetition frequencies greater than 15 kHz,
the average irradiance or radiant exposurc (radiance
or integrated radiance) of the pulse rain shall not
exceed the MPE (as given in 8.2) for a single pulse
equal in duration to the pulse train duration, T'
For wavelengths between 0.4 and 0.7 pm, the aversion
response time, 0,25 s, may be used unless purposeful
staring into the b€am is intended or antici'
pated. For wavelengths greater than 0.7 pm, lOs
may be used as the exposure duration unless purposeful
staring into the beam is intended or anticipated.
8.3 MPE for Extended-Source Viewing. MPE
values for ocular exposure to extended sources for
single pulses or exposures are given in Table 6. All
values are specified at the comea. (See 8.5 for special
qualificalions and use; see also Figs.5,6, and 7.) For
multiple pulse lasers or exposures, the MPE is deter'
mined using the exposure time of the pulse train
duration, 7'
8,4 MPE for Skin Exposure to a Laser Beam.
MPE values for skin exposure to a laser beam are
given in Table 7. These levels arc for worst-case
conditions and are based on the best available informanon.
E.4,1 MPE for Skin, Repeated Exposures For
repetitive-pulsed lasers the MPEs for skin exposurc
are applied as follows: Exposure of the skin shall not
exceed the MPE based upon a single-pulse exposure,
and the average irradiance of the pulse train shall not
exceed the MPE applicable for the total pulse train,
duration I. (See 8.5 for special qualifications and
uses.)
E.4.2 Wavelengths Greater than 1.4 lrm. For
b€am cross-sectional areas between 100 cm' and
1000 cm2, the MPE for exposure durations exceeding

l0 s is 10,000/,4" mW/cm', where A, is the area of
the exposed skin in cm2. For exposed skin areas
exceeding 1000 cm2, the MPE is 10 mWcm2.
8.5 Special Qualifications - Infrared. Available
data is not suflicient to define wavelength corrections
relative to l.06pm over the entire infrared range
(1.4 pm to I mm). At 1.54 Um, the MPE given in
Tables 5,6 and 7 has been increased by a factor of
100 for time periods shorter than I ps at inte als
greater than 100 s. However, no exlrapolation to
other wavelengths is justified on the basis of
presently available information.
9, M€asurements
9.1 G€neral. The laser classification scheme
described in.Section 3 is designed to minimize the
need for laser measurements and calculations by the
user. Generally, such measurements are required
only when manufacturer's information is not available,
when the laser or laser system has not been
classified by the manufacturcr in accordance with the
Federal Laser Products Performance Standard, or
when alterations to a system may have changed its
classification.
The cumulative error due to all sources of inaccuracy
(both systematic and statistical), including human
factors, operating conditions, and instrumental emors,
shall not exceed 1209o, or, if this is not possible, the
best that the state ofthe art reasonably will permit. It
is important to recognize that measurements improperly
performed may be worse than no measurements,
since they may imply a safe condition that does not
actually exist. Experience has shown that measurement
erIToBIs well in excess of !2OEo arc commonly
made and often are unidentified.
If measurements are performed, the accuracy of the
instrumentation should be traceable to national standards,
either directly to the National Institute of Science
and Technology (NIST) or to other transfer siandards
aceable to NIST. The NIST conducts programs
for assistance in meeting these requirements.
(See references in H4.)
Measurcments should be attempted only by personnel
rained or experienced in laser technology and
radiometry. Routine survey measurcments of lasers
or laser systems are neither required nor advisable
when the laser classifications are known and the
appropriate control measures implemented.
AMERICAN NATIONAL STANDARD ZI36.I-I986
If a laser or laser system is used outdoors over long
ranges, where the uncenainties of propagation
influence exposures, or where the beam divergence is
uncenain, measurements may be useful.
Measurements shall be made with the laser adjusted
fof maximum output for the intended use.
9.2 Intmbeam and Extended-Source Measurements.
If measurements or calculations are required,
distinction shall first be made between intrabeam
viewing and extended-source viewing in the 0.4 to
l.4pm wavelength region. For the purpose of this
standard, an extended source subtends an angle at the
observer's eye grqlter than the angular subt€nse,
c.;n, (shown in Fig.3), acmss the greatest angular
dimension of the source as viewed by the observer.
Table 8 gives the radiometric parameter ihal is
requircd to determine exposure to various laser
sources.
9.2,1 Radiance. The maximum radiance of an
extended source, such as the scattering of a laser
beam from a diffuse surface, shall be determined by
measurement. The measurement may average oYef
the appropriate conical field of view defined by the
angular subtense, crmin, or over a | -mm-diameter circular
area, whichever gives the larger value of radiance.
In the case of nonuniform extended-source
profiles, such as those resulting from inhomogeneous
beams or "hot spots," the measurement shall be
taken from the regions of greatest radiance.
9.2.2 Irradiance or Radiant Exposure
9.2,2.1 Limiting Aperture. The measurement
of inadiance or radiant exposure shall be made wiah
insruments that average over circular areas defrned
by the effective limiting aperture diameters given in
Table 9 or smaller diameters.
The sensitivity per unit area shall be sufliciently uniform,
when mapped with a l-mm-diameter beam, to
ensure the required accumcy of measurcment.
No conection for beam size or homogeneity is necessary
in cases where the entire beam enters the effective
limiting aperture. For larger beams, the measurement
shall be made in the area of the beam that gives
the maximum reading.
For distinguishing between Class 3b and Class 4
pulsed lasers (if manufacturer's specilications are
used), the maximum output irradiance or radiant
exposure which could be measured through a l-mm
circular apenure shall be used.
27

AMERICAN NATIONAL STANDARD 2I36.I-I986
See Fig. 13 for the anangement used for measurements
for the purpose of laser classification.
9.2.2.2 Field of View (0,2 to 0.4 lrm and 1.4
Fm to I mm Wavelengths). In measuring the inadiance
or radiant exposure from ultraviolet and farinfrared
extended sources, care shall be taken to make
sure that the field of view of the instrument is
sufficiently large to ensure the required accuracy of
measurement.
9,3 Instruments. Many optical power, energy, pulse
shape, and prf measuring devices available commercially
can b€ used to determine classification and
compliance with this standard. Instruments shall be
calibrated sufficiently well to pemit overall measurcment
accuracies of 120% wherever possible.
Measurements with instruments ftaving smaller effective
timiting apertures than those in Table 9 are permitted,
provided the appropriate correction factors are
apptied to ensure the required accuracy of measurement.
A variety of such instruments is described in the
refercnces listed in H4.
28
10. Revision of American National Standards
Refened to in This Document
When any of the following American National Standards
refered to in this document is superseded by a
revision approved by lhe American National Standards
lnstitute, lnc, the rcvision shall appty:
American National Standard
Cylinder Value Outlet and
ANSI/CGA V' l - 1977
American National Standard
Code. ANSI/|,IFPA 70- 1984
Compressed Gas
lnlet Connections,
Natlonal Elecftical
American National Standard Safety Standard for
Radio Receivers, Audio Systems, and Accessories,
ANSIruL 1270-1978
American National Standard General Safety Standard
for Installations Using Non-Medical X-Ray and
Sealed Gamma-Ray Sources, Energies up to l0 MeV,
ANSI/NBS Handbook I 14
American National Standard Specifications for
Accident Prevention Sighs, ANSI 235.1-1972
American National Standard Method of Marking
Portable Compressed Gas Containers to Identify the
Material Contained, ANSIrcCA C-4-1978
American National Standard Practice for Occupational
and Educational Eye and Face Ptotection,
ANSI 287.t-r979

o
Wavelength
Range
(Pml
Ultraviolet
0.2 to 0.4
Visible
0.4 to 0.7
Near Infrared
0.7 to I .06
Near Infrared
1.06 to 1.4
Far lnfrar€d
1.4 to 102
Submillirneter
102 lo 101
T
I
$
Table I
AMERICAN NATIONAL STANDARD ZI36.I-I986
Accessible Emission Limits for Sclected Continuous-Wav€* Lasers and f,aser Systems
Emission
Duration
(s) Class lt Class 2t Class 3$ Class 4
3xloa
3xl0{
3xloa
3 x loa
> l0
> l0
Emission duration > 0.25 s.

AMERICAN NATIONAL STANDARD ZI36.I -I986
Wsvelength
Range
(pm)
Ultraviolett
0.2 to 0.4
Visible
0.4 to 0.7
Near Infraredt
0.7 to 1.06
1.06 to |.4
Far Infrared
1.4 to 10'
Submillimeter
102
to 103
Table 2
Summary of Lev€ls (Energy and Radiant Exposure Emissions)
for Single-Pulsed Laser and Laser System Classiffcatlonr
Emission
Duration**
(s) Class I Class 3 Class 4
> l0-2
lo-e
to
o.25
t 0-e
to
o.25
l0-4
to
o.25
1tre
to
o.25
l0-e
to
o.25
l0J'cm-2
> 3l x l0-3 J . cm-?
>l0J.cm-2
>10J'cm-?
> l0 J cm-2
>l0J'cm-!
>luJ cm-
f Diffuse re8ection criteria (Table 3) apply from l0-e to 33 x l0-r s for Class 3. For > 33 x l0-l s exposure, the
maximum radiant exposure is l0 J . cm-2. Class I and 3 values are wavelength dependeflt (see Fig, 8).
30

Exposurc
Duration, r
(r)
l0-t
l0-{
10n
l0-6
lfrJ
l0-4
lrl
lr'
t0-
o.25
Table 3
Maximum Radiant Exposure Incident upon a Diffuse Surface
Which Will Not Produce Hazardous Reflections
Visible
(0.4 to 0.7 trn)
3.1 x l0-2
6.8 x l0-2
1.5 x l0-'
3.t x l0-l
6.8 x l0-'
1.5
3.t
6.8
l5*
20+
Maximum Radient Exposute
(J .cm-2)
Near Infraredt
(0.7 to 1.051 p|n)
CA(3.1 x lo-')
Ca(6.8 x l0-2)
C^(1.5 x l0-r)
CA(3.1x l0-r)
CA(6.8 x l0-r)
cA( 1.5)
ca(3.1)*
cA(6.8)*
cA( l5)'r'
cA(20)*
AMERICAN NATIONAL STANDARD ZI36.I- I986
Near lnfrared
(l.051 !o 1.4 Pm)
1.5 x l0-l
3.1x l0-l
8.0 x l0-'
3.1
8.0
15*
3l*
80*
100{'
General expression
for
duration , rortt tr t onCotr/l 5onCotl/3
values for classincation are limited to l0 J ' cm-' (see 3-3.3.1(3) and 3,3.4(2)).
values for CA will be found in Fig. 8,
Table 4
Minimum Optical Densities
Required for Protective EYewear
H}MPE
l=l0o
l0 = l0'
100 = 102
1 966 = r0l
1O 00O = lOa
l0O 000 = 10s
I 000 000 = 106
.Dr
0
I
a
3
4
5
6
3l

AMERICAN NAT]ONAL STANDARD 2I36.I-I986
Wavelength, ).
0rm)
Itraviolet
:00 to 0.302
303
.1(X
105
106
r07
.r08
r09
ll0
1t I
2
lt3
4
ll5 to 0.400
ll5 to 0.400
,\ible and Ncar Infrared**
l{}0 to 0.700
100 to 0,700
,-.^

o
Wavelength, L
$rm)
Ultraviolet
0.200 to 0.302
0.303
0.304
0.305
0.306
0.30?
0.308
0.309
0.3r0
0.31I
0.312
0.313
0.314
0.315 to 0.400
0.315 to 0.400
Visible**
0.400 to 0.700
0.400 to 0.550
0.550 to 0.700
0.550 to 0.700
0.,100 to 0.700
Near Infrared*
0.700 to | .400
0.700 to 1.400
0.700 to l.4m
Far Infrarcd
I.4 to 103
1.54 only
Table 6
MPE for Viewing a Diffuse Reflection
ofa Laser Beam or an Exlended-Source l,aser
AMERICAN NATIONAL STANDARD ZI36,I-1986
Exposure Duration l* Maximum Permissible Exposure
(r) (MPE) Notcs for Calculation and Measurement
l0-eto3xloa
l0-eto3xl04
lOato3xlOa
l0-4to3xl04
tOato3xld
lOaro3xlOa
l0-eto3xlOa
104ro3x104
lo-e!o3xl04
lOaro3xlOa
lo-eto3xl04
l04to3x 104
10ato3xlOa
10-e ro l0
l0to3x10a
loj ro l0
l0 to td
l0 to fl
Tr to 104
l0"ta3xloa
10-e to 10
l0 to 103
lorto3xld
loj ao lo-7
l0-? to l0 -
>to
lOa to lOj
* See Note in Section 8 for puls€widths less than I ns.
**See Fig. 7 and Fig. 83 of Appendix B for graphic representation.
NOTES; Ca = I for ,\, = 0.400 to 0.700 trm,
CA = 102.q1'-{
700)
for 1. = 0.700 to 1.051 pm (see Fig. 8),
Ce = 5 for l, = | .051 to 1.400 pm,
Cs = I for L = 0.400 to 0.550 pm,
ca = l0r5(r-o 550) for l, = 0.550 to 0.?m lrm (see Fig. 9],
Tr = l0 x 1020(r-4150) for ], = o-550 to 0.?fi) pm (see Fig. 9).
3xl0-rJ.cm-2
4 x l0-r J cm-2
6xl0-r J.cm-2
l.0x lO-2 J . cm-2
l.6 x l0-2 J cm-2
2.5x102 J cm-2
4.0 x l0-2 J cm-2
6.3x 10-2 J cm-2
l.0x l0-r J.cm-r
1.6 x l(f I J'cm-2
2.5x10.-r J'cm-l
4.oxl0-rJ'cm-z
6.3 x l0-r J ' cm-2
0.56tr/a J 'cm-?
I J'cm-2
l0 tll3 J. cm-2 . sal
2l J cm-2 'sil
3,83 r3lo J cm-2 ' sat
2l Cs J cm-z sil
2-l C8l0-r W cm-2 sr-l
l0 Co tllr J . cm-2 sil
3-83 CAi3t4 ! cm-2 sal
0.64 Ca W cm-2 sr-l
i o-2 J . cm-2
0,56 rrlo J cm-2
0,1W cm-2
1.0 J cm-2
or 0.56 tlla J ' cm-2, whichever is lower.
l-mm limiling ap€rlure
See Figs. 5 and 6 for graphical rcpresentation.
l-mm limiting aperture or d-in, whichever ls
greater
See 8.2 and Figs. 7,8,9,11, ard 12 for
graphic reprcsenlation and multiple pulse
limitations
See Table 9 for aperturcs.
See 8.5 and Fie, 6 for core,ction factors
33

AMERICAN NATIONAL STANDARD ZI36.I-I986
Wavelength, I
(pm)
Ultraviolet
0.200 to 0.302
0.303
0.3(X
0.305
0.306
0.307
0.308
0.309
0.3l0
0.31I
0.312
0.313
0.314
0.315 to 0.400
0.315 io 0.400
0.315 to 0.it00
Visible and Near lnfrared
I to t.aoo
-
Far Infrared*
1.4 to t0r
l -54 only
Exposure Duration I
(r)
lojto3xloa
l0-eto3xl0{
lo-eto3xl04
lo-eto3x loa
10-eto3xld
lo-eto3xld
lo-eto3xld
lfero3xld
l0+to3xld
tfeto3xld
lO-eto3xld
lseto3xld
lo-eto3xld
l0+ to t0
l0 to l0l
lorto3xlo4
10-e to lf7
l0-7 to l0
l0ro3x104
lo-e to lo-7
10-? to l0
>10
lo-e to l0{
*See 8,4.2 for large beam cross-sections.
o
34
Table 7
MPE for Skln Exposure to a Laser Beam
Maximum Permissible Exposure
(MPE) Notes for Calculalion and Me{rr
3 x 10.1 J . cm-2
4xl0-!J.cm-t
6xl0-!J.cm-2
l.0xl0-2J.cm-2
l.6x l0-rJ.cm-?
2.5x10-2J.cm-2
4.0x10-2t.cm-2
6.3x1(f2J'cm-2
l.0xl0-rJ.cm-2
1,6 x l0-t J . cm-2
2.5x10-rJ.cm-z
4.0 x ltrr J ' cm-2
6.3x10-rJ.cm-2
0.56tr/4J cm-2
tJ cml
x10-!w cm-l
2 cA x l0-2 J cm-z
l lcArr/4J.cm-2
0.2 Ca W cm-?
l02J.cm-2
0.56tr/aJ'cm-?
0.1 W'cm-2
1.0 J ' cm-2
or 0.56 t r/{ J ' cm-2. whichever is lor
I mm limiting apenure.
See Figs. 5 and 6 for graphic represo '
1 mm limiting aperture
Ser Figs. 6 and 8
I mm limiaing apedure for 1.4 to lmf
ll-mm limiting aFEnure for 0,1 to I
&

Laser Source
Extended Sources
(Angular subtense > c..)
lntrabeam
(Algular subtense < c,6)
Measurement
Eye MPE
Table 8
Required Radiometric Parameters
Visible
(0.4 to l4 pm)
Radiance
Inadiance
AMERICAN NATIONAL STANDARD ZI 36.1 -1986
Eye Skin
Ultraviolet Infrared
(0.2 to 0.4 pm) (l.4to l0! pm)
Irradiance
Irradiance
Tsble 9
Irradiance
lrradiance
All Wavelengths
(0.2 to l0r pm)
Irradiance
Inadiance
Maximum Aperture Diamet€rs (Limiting Aperture) for Measurement Averaging
Exposure
Duration, r
(s)
lOato3xlOa
Skin MPE
Laser
loato3xloa
Classification+ l0{ to 3 x loa
Visible and
Ultraviolet Nearlnfrared
(0.2 to 0.4 pm) (0.4 to 1.4 pm)
lmm
lmm
50 mm
WaYelengti Range
7mm
lmm
50 mm
Medium and
Far Infrared
(1.4 to l0' pm)
lmm
lmm
50 mm
Submillimeter
(0.1
to I mm)
ll mm
ll mm
50 mm
* The apertures are used for the measurement of total output power or outpul energy for laser classification purposes,
that is, to distinguish between all classes of cw lasers or bctween Class I and Class 3 pulsed lasers. The use of the
50-mm apenurcs as shown in fie ho zontal line labeled
"Laser Classification" applies only to thosc cases where
the laser output is intended to be viewed with optical instruments (excluding ordinary eyeglass lenses) or where the
Laser Safety Officer determines that there is some probability that the output will be accidentally viewed with
optical instrurnents and that such radiation will be viewcd for a sufficient time duration so a! to constitute a hazard.
Otherwise the apertures listed for Eye MPE and Skin MPE ar€ to be us€d,
For the specific case of optical viewing (beam collecting) instruments, the apenures li$ted for eye MPE and skin
MPE spply to the cxit beam of such devices.

o
AMERICAN NATIONAL STANDARD ZI36.I-I986
D
M
I
N
I
S
T
R
T
I
E
Controls
E
N
I
N
E
E
I
N
P
R
c
D
U
R
L
Table l0
Control Measur€s for the Four Laser Classes
Classification
Protcctive Housing (4.3. I I
Without Protective Housing (4.3,l.l)
Interlocks on Protective (4.3.2)
Service Access Panel (4.3.3)
Key Switch Ma$ter (4.3.4)
Viewing Portals (4.3.5. l 1
Op.ics (4.3.5.2)
Totauy Open Beam Path (4.3.6.1)
Limited Beam Path (4.3.6.2)
Remote Interlock Coflnector (4.3.7t
Beam Stop or Attenuator (4.3.8)
Activation Waming Systems (4.3.9)
Emission Delay (4.3.9.1)
Class 3b Laser Controlled Area (4.3.10.1)
Class 4 Laser Controlled Area (4,3.10.2)
Laser Outdoor Controls (4.3.1 l)
Temporary Laser Controlled Area* (4.1,l2)
Remote Firing & Monitoring (4.3.13)
Labels (4.3.l4)
Area Posting (4.3.l5)
Administrative & hocedural Controls (4.4)
Standard Opcrating Proccdurcs (4.4. l )
Output Emission Limilations (4.4.2)
Educalion and Training (4.4.3)
Autho zed Personnel (4.4.4)
Aligtmett Procedures (4.4.5)
Eye Protection (4.4.6)
Spectator
Conuol (4.4.7)
Service Personnel (4.4.8)
Laser Demonstration (4.5. l )
Laser Fiber Optics (4.5.2)
LSO shall establish Altemate Controls
LECEND X-Shall. r-Should. - No requiremcnr. V-Shall if Embedded Class 3b orClass 4,
tr - Shall if MPE is cxceeded, A - shall ifembeddcd Class 3a, class 3b, Class 4, * During Sewice Only
36

(YELLOW)
(BLACK
SYIEOL}
/ eosrrrol r \
\BOLD BLACK rErr€RNO/l
Fig, la
Sample Waming Sign for Class 2 and
Cenain Class 3a l:sers
AMERICAN NATIONAL STANDARD ZI ]6. I -I9116
/ rosrnon a \
\ Brlcx L€TrEn|tao
/

AMERICAN NATIONAL STANDARD 2I.36' I.I986
.llr
(BED SY$BOLI
Fig. lb
Sample Waming Sign for Cenain Class 3a Lasen
and for Class 3b and Class 4 Lasers
lwrirE)

AMERICAN NATTONAL STANDARD ZI 36. I - I 9116
LASER REPAIR IN PROGRESS
lh lbt Entsl Whcn Uglrt ls Harhlng
EYE PROTECTION REOUIRED
Fig. lc
Sample Waming Sign for Temporary
Controlled Area
-19

AMERICAN NATIONAL STANDARD 2I.16,I.I986
4(l
AREA
SENSOR
NTERLOCKS
(NONDEFEATABLE
DEFEATABLE)
FLOORMAT
Fig. 2a
Area/Entryway Safety Conrols
for Class 4 Lasers

l---f-
APPLICABLE MPE
AMERICAN NATIONAL STANDARD Z I]6. I .I986
E"PANlc" BUTToN
- CLASS 4
BARRIER,
SCREEN,
CURTAIN
8 '.PANIC''
BUTTON
INDICATOR
(VISIBLE
OR AUDIBLE)
Fig. 2b
Safety Controls for Class 4 Lasers wherc
Arca,/Entryway Controls are Inapprcpriate
4l

I
AMERICAN NATIONAL STANDARD ZI.J6.I.I986
> 6 METERS
BARRIER
Fig. 2c
Unsupervised Laser Installation for
Demonstration [.aser
r/ncL\ss 3b oR 4
ru(LESS THAN
6 METERS)

3 METERS
Fig. 2d
Supervised Laser Installation for
DemonsFalion Laser
AMERICAN NATIONAL STANDARD 2 I 36. I.I 9It6

o
O
AMERICAN NATIONAL STANDARD ZI 36. I. I986
BARRIER
Fig. k
Superviscd Laser Installation for
D€monstration Laser
I
AUDIENC
ldESr

s Nvtovu
t'llt$t Nr(uluto)
tsNfrgns uvtncNv
o o
Ot q, F Or (t {. t7 N rat
t;
F
2
*o'
u,o'
3 b
9 c
( J E
! o
-c ot
!l
EE
E=
(DE
or c:
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i.s
o-g
FJ
[Elnr*or''.- 5
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le e9eQQq90-o
xE,
o
at
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: ]
;.9
oo
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.

I
AMERICAN NATIONAL STANDARD ZI]6.I- I986
I
E
t!
E
3
o
o.
x
u,
F
2
c
ro-'r
to
to- 6
5r
:l
;l
8l
6l
']
2
,I
I
6
4
2
,t 86
4
z
rl
I
6
4
\|
2
ffi
K':lc
lo' to-' to-t lo - ?
EXPOSURE DURATION (S)
NOTE: For corrcction factor infornation at wavclcngth$ b€lween 0'7 Fm and 1.4 pm, scc Table 5
Fig. 4
MPE for Direct Ocular Exposure to Visible and Near Infrared
Radiation (1"=0.4 to 1.4 Fm) lntrflb€am Viewing
(Angular Subtense

o
"ro
ro
to
^ lo't
E
o
lrl
e
:)
v,
o
o.
x
l!
F
2
= to'2
E
8
8
6
4
o.20
0.26 0.28 o.so
IvAVELENGTH (F,ml
MpE for Diroct O"ur", eff.usr" ro Ultraviolct Radiarion
(Intrabcam Vicwing and Extcndcd Sourccs) for Eloocurc
Durations from t0-e to 3 x lds.
*Unless 0.561| /a is cxcccded (possiblc for erposurc ouraiions < I o s ar ], = 0..m5-O.3tS |rm).
AMERICAN NATIONAL STANDARD 2I.16. I - I9116
I
8
6
ll
;)
)
J I
o.34
I' 6l
2
I
8
6
4
t.
I
I
6
4
to'3
5
2

o
AMERICAN NATIONAL STANDARD 2I36. I.I986
F
z
g
< ,^-,
4lJ
to-! to-' to-l
EXPOSURE OU RAT IO I{ (SI
. Loi to_'J.cm-2
l.Brto_?J. cm-2
3.2 r l(l2 J cni-z
s.6 r|o_2 J cm_z
t.or ro-r ,J. crn_z
l.8 rlo_lJ.crr-2
3.2 r ro_rJ. cd2
3.6 r lo-rJ cm-?
t.oJ.cm_2
2 4581 2 ,l 681 2 4681 2 468
Fig' 6
MPE for Dircct Ocular Exposurc to Ultraviolet ()' = 0.315 to 0',rc0 t .)
and lnfrared (1" = 1.4 pm to I mm) Radiation (lntrabeam Viewing
and Extended Sources) for Single Pulses or Conlinuous Exposures

49
do
( r-,rs.?-uI3.0)
ItNvt0vu o:llvugllNl
(o{ N -
I
5z
o
':
@
o
t
:
. e
l
el I
t
to
o
o
E
a
5 - . Eo
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ao
(o
@ =
6 z E
> =
O E
F t
e E
s $ . E
" i a;**
O E E;E&
@
0
rt
tl
.E: trieFa
bg; f;-r:g
*E g?gE
JO
u
6
@
t
\
9 Y - . , . 4 = :
-! 3 E=eE
e: l.F:;E
? d ; r r r
"
d .E.*
; EesH
^1" Ba/\g
e; jl gH
*,r-{ g:58
ti<
'll
r!B
..|
EZ
-o
.'oFoo,,,..J= e.
g e9'9 9e99e-9^9
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b
o
ao
Et
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g;
24 -:
trr o
FF
_'1'o9 e eQ;;;;;f
eIi6iis$5es9.
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*"g"gs sry;ilit:
a
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t il| i ill
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@
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t
JO
o
o
AMERICAN NATIONAL STANDARD
Z I.]6.I-
I9116

o
o
AMERICAN NATIONAL STANDARD 2I36.I.I986
g
E
0
t- a)
f -
o
F
c
E
o
(,
!t
2
50
Ca = I for I = 0.4 to 0.7 [m'
c^ = l02q^-oD forl=0.7 to l.o5l rm:
Cr, =5forl= 1.051 to l.4pm.
WAVEL€NGTH (;rml
Fig. 8
Correction Factor C^ for Wavelengths Between
0.7 and l.4 tm (From Tabtes 5 and 6)

z
I
o.s50 o.575
NOTE: See Table 5 and 6.
i4
0.600 0.625 0.650 0.6?5
WAVELENGTH (/rm)
Fig. 9
Correction Factors Cs and T, for Wavelengths Belween
0.55 and 0.7 um
AMERICAN NATIONAL STANDARD ZI36.I-I986
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to
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EXPOSURE OURATION (SI
Fig. l0
Ocular MPE for tntrabeam Viewing (Angular Subtense

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too tooo
EXPOSURE DURATION (S)
Fig. I I
Ocular MPE for Extended Sources (Angular Subtense >c,.,", in Fig. 3)
as a Function of Exposure Duration and Wavelength
AMERICAN NATIONAL STANDARD Z I 36. I. I 9Ii6
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AMERICAN NATIONAL STANDARD ZI J6.I.I986
;flNG LENS
(P=5 DIOPTERS OR
GREATER)
,o
SOURCE
SOLID ANGLE OF
ACCEPTANCE
(sEE 9.2) APERTURE STOP
(SEE TABLE 9)
,a
Fig. l3
Measurcment Arrangement Used for Purposes
iif Laser Classifi cation
DETECTOR

o
Appendixes
Appendix A
This Appendix is not pan of American National standard 2136.l-1986, bul is intended fof
information only.
Examptes ofTypical Lasers or Laser Syst€m Classificstion and MPE Values for Selected Laserc
Since the laser classification was designed to include
all types of lasers operating at essentially any
wavelength or pulse duration, the rules of
classification (see 3.2) may appear complicated. To
assist in the classification of commonly available
fasers, Tables Al and A2 have been prcpared to aid
the user in rapidly determining lhe required
radiometric parameters needed to classify a laser and
its applicable class once the required output
parameters are known. Table Al applies to cw lasers
(potential exposure time >0.25 s), and Table ,A2
applies to pulsed lasers. To classify a repetitively
pulsed laser, the values in Tables Al and AZ are not
generally applicable but may be used as a first step in
estimating approximately what class the laser will fall
into;
56
the user should then apply the rules given in
Section 3 of the standard.
Calculations rcquired for some classifications are
presented in Appendix B.
The MPE per pulse values given in Section 8 can be
applied to any laser or laser system operating at
essentially any wavelength, pulse duration and
exposure duration. Tables ,43 and ,{4 have been
preparcd to assist in determining the intrabeam MPE
for the eye and skin for several commonly used
lasers. Table A3 applies to selected cw lasers and
Table A'4 applies to selected pulsed lasers.
Calculations required to detemire &e MPE for
various situations are prcsented in Appendix B.

,l
,,
..-
-
ro
(0. I to O-2E
lrrn)
(0.315
ro 04!m)
(0.4
ro 0.?
Im)
(0.? to 1.4 FF)
Fd Inf@d
(l.4 ro l0oIm)
Far InrmEd
{O. l to I mm)
YAG (Quadopled)
H€lium{rdrDium
Helium-Sctenium
YAC (Dolblcd)
Helium-Neon
Krypton
cw Galliutn-Aluminum
YAG
Hydro8en Cyanid.
Table Al
Typical Laser Classification - continuous.Wave (CW) Lasers
125 rm only
35l.l,363.8 nm only
350.?,1564 motrly
457-9, 4?6.t, 488.
(l0lines)
J33nnl
632.8 m
617. I, 530.9, 676.4 nm
o.8s
Im (20 " c)
0-905
ll'n (20 " C)
l,0li, 1.152
xn only
5.0-5.5In
10.6!m
3.39 lrn dly
IIEBE
3l7pm
APPENDTX
ExcnF -Cl!$ l' Cbs.? Clasr 3
Cl6 4
< 0.?5 x lfr W
s 0.3!r trr w
>Clsss l b Cl.ss I blr < 0.5 w > 0.5 W
>ctas.lhr0.5w
>Ctasslbut30.5W >0.5W
- >Chs|butso5w >0.5\'
' > Cllrs I but 0 5 !Y
- > Clu\' I but s lr'5 W >lr't \4
- >ChsrIbut0i\'
- >ClNlburso.sw >05[
* Assumes no mechanical or elecrrical design incoryorar€d inro ldser $ysrcm to prevent exposurcs from lasling lo 1-., = I hours (one workdry): othetwis€
rhe Class I AEL could b€ larg€r than lab{llared.
Table A2
Typical Laser Classificalion - single-Puls€ Lasers
Wa'./eng.h
R,n8. l-e. wrvelen8th Pulse Duo(ion EremPl.clrs l c|&s 3 Hi8n.Pog€rcls.4
(O.l ro 04 trn) Q*w (Q{adruplcd)
Ruby (Do$bl.d)
(DoubLd)
Rhodmio€ 6G
(Dy. Lasco
266 nn
532 nh
694.3 nm
450-650 nn
1.064 Fm
L54 Fm
l0to 30x ltr's (Q-sw)
l0ro 30x l0-'s (Q-se)
l i = ?0 'r0" s rQ-sw)
: !0x l0-'i (Q-sw)
: lOlo l00x l0 " s (Q-sw)
I tu t0(tx l0'r (Q-sw)

APPENDIX
Laser Type
Helium-Cadmium
Argon
Helium-Neon
Krypton
Neodymium: YAG
Callium-Arsenide
at room temp
Helium-Cadmium
Nitrogen
Carbon-dioxide
(and other lasers
1.4 lrm to 1000 pm)
Table A3
Intrabeam MPE for the Eve and Skin for Selected CW Lasers
Primary
Wavelength(s)
(nm)
441.6
488/s r4.5
632.E
647
I,064
905
325
337 .l
a)
b)
c)
a)
b)
d)
a)
b)
c)
d)
Exposure Limit
Eye Skin
2.5 mW ' cm-2 for 0.25 s
l0 mJ ' cm-z for l0 to ld s
I pW.cm-r fort> ld s
2.5 mW ' cm-2 for 0.25 s
10 mJ ' cm-2 for l0 s
170 mJ . cm-z for t > 453 s
t7 pW . cm-2 for t > lOa s
2.5 mW . cm-2 for 0.25 s
l0 nJ . cm-? for lo s
280 mJ ' cm-2 for t > 871 s
28 pW cm-? for t > ld s
1.6 mW cm-z for t > 1000 s
0.8 mW cm-2 for t > l0O0 s
0.2 W ' cm-2
fort> l0s
0.2 W . cm-2
fort> l0s
0.2 W . cm-?
fort> l0s
1.0 W . cm-2
0.5 W . cm-2
fort> l0s
lJ.cm-2forl0to3xlOas a) 1J'cm-2for
l0 to 1000 s
b) l mw .cm-2 for
t> 1000 s
10,600 0.1 W . cm-2 for >10 s 0.1 W.cm-2 for
t>l0s
Table A4
Intrabea4 MPE for the Eye and Skin For Selected Pulsed Las€rs
Primary
Maximum Pemissible Exposure
wavelength(s) Pulse
Laser (nm) Duration Eye Skin
Normal-pulsed ruby
Q-switched ruby
Rhodamine 6C dye laser
Normal pulsed
neodymium
Q-switched neodymium
58
694.3
694.3
= 500 - 700
1064
l0@
= I msec
5 - 100 nsec
0.5 - 20 psec
= | msec
5 - 100 nsec
t0-s J ' cm-z
5xl0-7J'cm-2
5x l0-?J.cm-2
5xl0-5J'cm-2
5xl0{J.cm-2
0.2 J ' cm-2
0.02 J ' cm-z
0.03 to 0.07 J . cm-2
1.0 J ' cm-z
0.1 J . cm-z

JO
JO
,t'
Appendix B
Calculaaions for Hazard Evaluation and Classification
Bl. General
Calculations are not necessary for hazard evaluation
aod classification in many applications; however, in
outdoor applications and other specialized uses where
eye exposure is contemplated, several types of calculations
permit the important quantitative study of
potential hazards.
Mathematical symbols used here are defined in 82.
Hazard classification and MPE determination may
requirc the use of fomulas in 83. Formulas useful in
estimating exposure at significant distances from the
laser and in optically aided viewing are presented in
84.
Figures Bl, 82 and 83 illustrate rhe three conditions
of ocular exposure to laser mdiation,
82. Symbols
The following symbols are used in the formulas of
this Appendix.
a = Diameter ofemergent laser beam (cm)
b, = Diameter of laser beam incident on a
focusing lens (cm)
= Major axis ofelliptical cross-section
beam (cm)
c = Minor axis of elliptical cross-section
beam (cm)
bl = Width of rcctangular beam (cm)
Cl = Height of rectangular beam (cm)
d" = Diameter of the pupil of the eye (varies
from approximately 0.2 to 0.7 cm)
= Limiting object size of extended object
(cm)
D" = Diameter of the exit pupil ofan oprical
system (cm)
Da = Diameter of laser beam at range r (cm)
D, = Diameter of objective of an optical iystem
(cm)
e = Base of natural losarithms
APPENDIX
/ = Effective focal length ofeye (1.7 cm)
.6 = Focal length of lens (cm)
F = Pulse-repetition frequency, prf(s-r)
G = Ratio of retinal iradiance of radiant exposure
received by optically aided eye to
that received by unaided eye
H, E = Radiant exposurc (II) or iradiance (E)
at range r, measurcd in J ' cm-2 for
pulsed lasers and W ' cm-2 for cw lasers
t/,, E, = Emergent beam radiant exposure (I1a) or
inadiance (8") at zero range (units as for
E,m
Ha = The potential eye exposurc, in the
appropriate units, utilized in the
determination of the optical density
ofprotective eyewear
l, = Radiance ofan extended source (W.
cm''sr'
lp = lntegrated radiance ofan exlended source
(J'Cm - 'Sr ',,
m = Atmospheric attenuation coefficient
(cm-r) at a particular wavelength
NA = Numerical aperture of optical fiber
P = Magnifying powerofan optical system
O = Total radiart enorgy output of a pulsed
laser, measured in joules
r = Range fmm the laser to the viewer or to
a diffuse target (cm)
rr = Range from the laser target to the viewer
(cm)
11 ."" = Maximum range from the laser target to
the viewer where extended-source MPE
applies (cm)
R = Radius of curvature of a specular surface
(cm)
r,vom = The distance along the axis ofthe
unobstructed beam liom the laser
beyond which the iffadiance or
radiant exposure is not expected to
exceed the appropriate MPE (cm)
S = Scan rate of a scanning laser (number of
scans across eye per second)
, = Duration ofsingle pulse (s)
T = Total exposure duration (in seconds) ofa
train of pulses
cr = Viewing arigle subtended by an extended
)v

o
o
APPENDIX
source
d-in = Minimum angle subtended by a source for
which extended-source MPE applies (rad)
p = Atmospheric attenuation coefficient
(cm-r) at a panicular wavelength
0 = Emergent beam divergence measured in
mdians I i e
0r = Emergent beam divergence of the major
cross-sectional dimension of a rectangular
or elliptical beam, measured in radians
0? = Emergent beam divergence ofthe minor
cross-sectional dimerlsion of a rectangular
or elliptical beam, measurcd in radians
O = Total radiant power output of a cw laser,
or average radiant power ofa rcpetitively
pulsed laser, measured in watt$
pi. = Spctral reflectance of a diffuse object at
wavelength ?',
4 = Maximum angular sweep of a scanning
beam (rad)
0u = Viewing angle (see Fig. 83)
orn = Mode field diameter of single mode
optical fiber (pm)
83. Examples of MPE Determination and Laser
Classification
B3.1 Determining the MPE for Intrabeam Viewing
for Particular Exposures
83.l.l Single-Pulse Laser MPES.
MPEs for single-pulse lasers may be calculated from
the information provided in Tables 5, 6 and 7 (as in
Examples I and 2) or they may be rcad directly from
the graphs of Figs. 4, 5, 6 and 7.
Emmple l: Single-Pulse Visible Laser. Determine
the MPE for a direct intrabeam exposurE to a
694.3 nm ruby laser pulse having a duration of
8 x l0r s (0.8 ms).
The appropriate MPE, as given in Table -5, is
MPE: t/ = 1.8 x l0-3 r3la J cm-2
Substituting the yalues for , in the example yields
60
I Jiv lO-3 r
MPE: l1 =#
-1,l
_ (1.8x l0-3x8x 10r)
a!8 x Io{
l -1, ., ! ^-6
1.68 x l0-'
Since E . , = H, the MPE may also be expressed as:
H 8.6 x l0+ J'cm-2
,\nYL: E =
r 8xl0- s
=l.lxl0-2W.cm-z
Example 2: Single-Pulse Near Infrarcd l,aser. Detet
mine the intrabeam dircct-viewing MPE for t
1.081pm (Nd: YAG) laser having a pulse durationd
Ex loa s. The MPE as given in Table 5 is
MPE:H = 9t3/a x l0-3 J/cm2
= 9(8x loa)3i a x l0-3
=4.3x10-5J'cm-z
Another way to approach this problem is to note thd
in Fig.8, the direct-beam MPE for this laset is fivc
times that for the visible laser having the same expo
sure duration (see Example l). Thercfore, the MPE
for this exposure is
MPE: H = 5x(8.6x 10-6 J cm-2)
= 4.3 x 10-s J cm-z
and in terms of irradiance,
MPE: E = 5 x(l.l x l0-2 w' cm-2)
= 5.4x l0? W' cm-2
83.1.2 Rep€titively Pulsed Laser MPE.
To determine the MPE applicable for an exposure t0
a repetitively pulsed laser one must know the
wavelength, prf, duration of a single pulse, and dwa'
tion of a complete exposurc. The MPE per pulse fot
repetitively pulsed intrabeam viewing is n-rla timel
the MPE for a single pulse exposure where n is thc
number of pulses found fmm the product of the prf
and the exposurc duration (T) as defined in 8.2.2
This MPE applies to all wavelengths gr€ater than
700 nm. For wavelengths between 40O and 700 nrn,
the MPE as calculated on the basis of n-rla also mu$
not exceed the MPE calculated for |rl seconds when
nr is sreater than l0 s,

I I
Tlir,'i :":,3*1;If;iTrjfrTfJfiiff"#r
'
. o
-
ance or radiant exposure (radiance or int€grated radiance)
for the pulse ffain duration (f) is limited to the
MPE for one pulse of this inadiance or radiant exposure
(radiance or integrated radiance) whose duration
is the maximum exposurc duration, fmax.
Exarnple 3: Repetitively Pulsed Visible Laser with
Very High PRF. Determine the direct intrabeam
MPE of a 514.5 nm (Ar) laser and operating at a prf
(F) of l0MHz a pulsewidth t of l0ns (10-u s).
Assume an exposure duration I of 0.25 s.
Since the prf is greater than 15 kHz the avemge radiant
exposure limitation applies. From Table 5,
MPE (avg):H < 1.8 t3lax l0-3 J. cm-2
= 1.8(0.25)3/a x t0-3 J.cm-z
=6.36x10{J.cm-?
This may also be expressed in terms of average irradiance.
-2
rru'u - z - 6'36x!-o:l' cm
=2.55xlo3W
cm2
Example 4: Repetitively Pulsed Near Infrared Laser
with Moderate PRF. Detemile the intrabeam
direct-viewing MPE for a 905 nm (GaAs) laser which
has a pulsewidrh r= l0Ons (107s) and a prf
F = I kHz. Since the 905 nm wavelength will not
p,rovide a natural aversion response such as a visiblewavelength
laser would, assume a l0 s exposure
duration f for this panicular laser application. The
total number of pulses in a l0 s exposure duration is
determined from the product of the exposure duration
and the prf, i.e., n = F xT equals lOa pulses. From
Fig. 12, the reduction factor n-lla is found to be 0.1.
From Table 5 or Fig.8, the wavelength conection
factor is 2.6 at 905 nm and th€ MPE from Table 5 for
a single pulse is:
MPE. H = (5C,{
x l0-?; J. cm-2
.'.MPE/Pulse: H < r?-u4(5C,{ x l0-7; J . cm-z
< 0.1 x5 x2.6x l0-7 J . cm-?
, I "."*. ,n" "ru .-o,,j:o ui'u'J,nu,",,". .**,",.
for the dumtion of the entire oulse train would be:
MPE/(cum) : t/ < ( l0 s) (101 Hz) '
(1.3x l0-? J . cm-2)
=l.3xl0-3J.cm-z
APPENDIX
This may also be exprcssed in terms of average irradiance,
.. . ^ .^-r. -t
MpF.F= it _ l.JXtu-J'cm-
T los
= t.3x 104 W ' cm-2
Example 5: l-ow-PRF, long-Pulse, RePetitively
Pulsed Visible Laser. Determine the MPE for a
632.8 nm (He-Ne) laser where T = 0.25 s, t = l0-3 s,
andF=l0OHz.
The MPE per pulse is given by the product of n-rla
and the MPE for a single pulse. [n addition, since
this is a visible laser, the MPE.per pulse must not
exceed the MPE calculated for r, when nt is greater
than l0 s.
nt=t'F'T
= (10-3 s) (0.25
s) (t00 Hz) = 2.5x 102 s
(Eq Bl)
Since this is less than l0 s, the latter does not apply.
The total number of pulses in the 0.25 s exposure is
n = F x I equals 25. From Fig. 12 the conesPonding
value of n-rla is 0.45.
From Table 5 or Fig.4 lhe MPE for a single l0-3 s
pulse is
MPE: H ( 1.8 tlla x l0-3 J cm-z
= l.0lxl0-s J'cm-2
and the corresponding MPE per pulse for a 0.25s
exposure is:
MPE/Pulse: Hi < (n-rl4) MPE
= (0.45) ( l.0lxr 0-5)
=4.55x10{J'cm-2
ln terms of average power,
MPE (average power): E.,e= H ' F
= (4.55 x l0{ J . cm-z)( l0O Hz)
=4.55x10aW'cm-2
(Ec 82)
Example 6: One-Pulse Croup, Shon-Pulse L,aser'
Find the MPE of a p-switched ruby laser (694.3 nm)
6l

APPENDIX
which has an output of three 20 ns pulses, each
separated by l0O ns.
This is not a repetitively pulsed laser in the usual
sense (that is, one having a continuous train of pulses
lasting on the order of 0.25 s or more with the pulses
being reasonably equally spaced). The inaabeam
visible MPE per pulse is given as the product of n-rla
and the MPE for a single pulse (from Table 5), or the
MPE per pulse is
MPE/Pulse : H < 1n-rla; lMpE; J' cm-2
= 3-l/a (5 x l0-?)
= 3.8x l0-7 J.cm-2
Example 7: Repetitively Pulsed Pulse Groups. Find
the MPE for an Argon laser (488 nm) used in a
pulse.code-modulated (pcm) communications link.
The laser presents l0a "words" per second (that is,
10" pulse groups per second) and each word consists
of five 20 ns pulses spaced at coded intervals such
that each pulse group lasts no longer than I ps.
The effective prf of the pulse train is equal to the product
of the number of words per second and the
number of pulses per word, or 50 kHz. Since this is
greater than 15 kHz, the cw or average power limitation
applies. Thus, the corresponding MPE from
Table 5 or Fig.4 for a nonmodulated laser and an
exposure duration of 0.25 s is:
or
MPE:11 = 1.8 l3l4x10-3 J - cm-z
I R,l/4 Y l n-l
MPE : E( ""' ^ '" W cm-2
I
=2.55x10-3W.cm-2
This value is compared with the average irradiance of
the laser which is obtained from the effective duty
factor of the pulse train and the peak power. The
duty factor is defined as the ratio of the pulse width
(r) to the period, which can also be expressed as
t x f. In this example the effective duty factor is
20nsx50kHz=0.001 and hence the average irradiance
is 0.001 times the peak inadiance.
83.2 Determining When to Use the Extended-
Source MPEs.
The intrabeam MPEs are used in all situations of
intrabeam viewing of thc direcl beam or specularly
62
rcflected beam, except for close viewing of laser
diodes or diode arrays. The intrabeam MPEs are also
used when viewing an extended source at a distance
greater than r I ll's .
83.2.1 Extended-Source MPEs Application.
The extended-source MPEs are applied only in the
spectral region of 0.4 to 1.4 pm where the source size
is significantly larger than a "point;'and wherc the
conesponding retinal image in the viewer's eye is
definitely not a "minimal spot". Diffuse reflections
arc extended sources at close viewing distances;
therefore, depending upon environmental considerations
and the laser, it may be necessary to consider
the extended-source MPEs. Class I and 2 lasers are
not capable of producing hazardous diffuse
reflections, and only the direct ocular inrabeamviewing
MPEs arE applied (exc€pt in the case of
intrabeam viewing of semiconductor diode lasers and
laser arrays), Class 4 lasers are always capable of
producing hazardous diffuse reflections at close viewing
distances. Class 3 lasers will not pmduce hazardous
diffuse reflections for exposure times

JO
D1 . cosO,
cQnm = --l-
'lnar
Emmple 8: Finding the Maximum Distance Where
the Extended-Source MPE Applies. Find the maximum
distance rr for a visible laser having an emergent
beam diameter d = I cm, a beam divergence
Q = l0' rad, and a pulse duration of 20 ps. A diffuse
matte target is placed l@ cm from the beam exit
of the laser; that is, th€ target distance r = 100 cm.
The relation of D1 (in Fig. B I ) to the emergent beam
divergence and diameter is:
Dt=a+r'Q
(Eq 84)
At sholt target distances, where (r.Q) is nearly zero,
Dz is clearly the same as a, or I cm, and using Eq 83
and finding o,n,n from Fig. 3, we have:
Dlcos0u
rlmu=c4oin
which for small viewing angles, where cos0v = l, is
a (l cm) (l)
rr drw = - = -----j-:--:::r+j-.-_ = 625 cm
oq.i^ (1.6x l0-r rad)
Thereforc, for distances less than 625 cm, the applicable
MPE from Table 6 or Fig. 7 is.
MPE=l0rr/3J'cm-z.sar
or
MPE = 10(20x l0{)r'3 J 'cm-? . sal
=2.'l2xll-t J .cm-2 . sal
and for greater distances the applicable MPE from
Tabte 5 or Fig. 4 is 5x l0-7 J' cm-2.
This example illustrates that for most pulsed lasers
the extended-source MPEs are applicable for diffuse
reflections in such indoor areas as laboratories.
Exceptions would be focused-beam diffuse
reflections, such as those occuning in microdrilling
processes, For visible cw lasers where the exposure
time could b€ 0.25 s or greater and where a is often
only 0,1 to 0.2cm, q;" is sufficiently great (10-
24 mrad) that the maximum distance r 1 at which the
extended source MPEs apply would be only a few
centimeters and the intrabeam MPEs would be more
rclevant. For a = 0.1 cm, and o"nin = 24 mrad,
rl mlx
= a/ohin = 4.2 cm.
Exatnple 9: Extended-Source MPEs for Diffuse
Reflections Expressed as Incident-Beam Irradiance or
Radiant Exposure. In most cases it is simpler to
determine whether the incident-beam irradiance or
radiant exposure is capable of producing a hazardous
APPENDIX
diffuse reflection, rather than having to deal with less
familiar radiometric quantities such as radiance.
Consider the laser defined in Example 8. Since the
extended-source MPE is exprcssed as an integrated
radiance, it is necessary to determine the beam radiant
exposure at the target which Produces this
integrated radiance. The relation is
H.o\
L" = -------:-::
OI
H = --------L
Pr
where L, is determined from Table 6.
(F.q B5)
Hence, the MPE expressed for a 100% - reflectance
white diffuse talget is
(3.14J Q.8x l?-t J . cm-2 . sr
1.0
= 0.88 J cm-'
NOTE| Eq 85 is stricdy true only for a theoreticalty perfect
Lambenian surface: however, unless a surface has a highly
glossy !;heen, it may b€ considered sufficiently
"diffuse"
ro apply this formula and the diffuse-surface MPES. The
above rcsult could have been obtained by interpolating the
values in Column 4 of Table B I belween l0-" and l0* s.
Example l0: Sp€ctral Corrections for Near Infrared
Laser MPEs. A GaAs laser operating at room temperature
has a peak wavelength at 0.904 pm. What is
the MPE for a single pulse of 200 ns duration?
The MPE can be calculated fmm the informalion in
Table 5 and 6 or can be determined as follows: From
Fig.8, note that the spectral corection factor C,{ is
2.5. From Fig.4, the MPE for direct viewing of the
source is H = (2.5) (5x t0-7 J 'cm2; = l.28xl0{
J'cm-2 for a single pulse. Similarly, the extendedsource
MPE (from Fig.7 for 200 ns) for sources subtending
an angle greater ihan 3.3 mrad is
(2.5) (5.8x l0 2 J .cm 2
sr-r;=
1.46 x 10-r J cm-z ' sal .
NOTE: Unlike gas or solid-statc lasers, some semiconductor
diqde lasers o. laser anays could be an extended source
at close viewing range within the beam if the line source
were magnified by a projection lens or a microscope-

APPENDIX
B3.3 Central-Beam Irradiance or Radiant Exposur€.
Often the beam inadiance or radiant exposure is not
provided in a laser's specification. However, if the
laser is single mode and has a Gaussian beam profile,
the central-beam values may be obtained from lhe
beam diameter specilied at l/e points and the beam
radiant power or energy. The relations are
- 40 1.274
(Eq 86)
Lo= -.......--l =
"
17a' 4-
or
. _" Q _1.?7Q
,to - -------;
a
- ------lta'
a'
Often the beam divergence or diameter is specified at
lle2 points rather than aa the lle points, so that the
above relations would provide average values rather
than central-beam values. In such a case, divide the
diameter specified at the l/e2 points by {7 to obtain
the corresponding l/e value. Note however, that the
MPEs can be specified as averaged either over a I
mm or 7 mm aperture depending on the wavelength.
In this case the calculated values of 11., or 8,, may not
be relevant.
83.4 Laser Classification.
Examples I I through 16 show nrethods ofcalculating
parameters necessary for classifying lasers in accotdance
with Section 3 of the standard.
Example Il: Classify a single pulse (prt

fa
,l
,o
pipe; Class 4, if more than 0.5 W is emitted from the
laser system as an unenclosed beam; or Class 3b, if
after passing through beam-forming optics the total
optical power in the beam werc greater than 5 mW
but less than 0.5 W(see3.3).
Etample 15: Find the appropriate beam diameter to
be used for calculations in this standard if a laser
beam diameter is specified as being 3 mm in diameter
as measured at l/e'-of-peak-inadiance points. The
beam is further specified to be single-mode and Gaussian.
Since the beam is Gaussian, use may be made of the
relation that the beam diameter measured at the l/e2
points is greater by a factor of {T= l.4l than the
diameaer measured at the l/e points. Henc€:
0.3 cm
a=- = tr-l I cm
\12
This exercise was purely academic, since the calculation
of diameters below 7 mm is not necessary to
determine laser classification. The value a could,
however, have been used for the laser range equalion
Eq 87 (see 84.l ).
Emmple 16: Classify a 0.6328 pm visible laser (He-
Ne) used as a remote-control switch. The laser is
electronically pulsed with a I mW peak-power output,
a pulse duration of 0.1 s (hence an energy of
l0{ J per pulse) and a beam diameter of I cm. The
recycle time of the laser is 5 s (maximum
prf = 0.2 Hz).
Since the device is pulse.d with an exposure duration
of 0.1 s, the applicable MPE for intrabeam viewing
from Table 5 or Fig. 4 is 3.2 x l0-3 W.cm-? or
3.2 x lt' ! . cm-z. Using Eq 86, the emergent beam
radiant exposure per pulse is l.27xl0{J.cm-2,
which is less than half the MPE, indicating the laser
is Class I if repeated exposure is not considered possible.
In the absence of biologic dara and MPEs for
exposures repeated at prfs less than I Hz, the exposures
should be considered linearly additive. Following
this rule, at least two exposures are possible considering
all three aspects in a hazard evaluation (see
3.1); the prudent approach would be to apply a caution
label to the device with the words "Do Nor Stare
Continuously Into Laser Beam".
APPENDIX
84. Formulas and Examples Useful in Evaluation
of Various Laser Applicftions*
84.l Correction for Atmospherlc Attenuation.
Beam irradiance, f, or radiant exposure, f/, for a nondiverging
beam at range r which is attenuated by the
atmosphere is given by
E_E ^itr
or
H = Hoe-['
(Eq 87)
NOTE: The anenuation coeffcic[I. l-1. varies from l0{ per
centimeter in thick fog to l0-' in air of very good visibilily.
The Rayleigh scattering coeflicienr at 0.6943 pm is
4.llx l0 xcm-r, and l.8x l0-7cm-r at 0.500 um, The
eflect of acrosols in cvcn thc clcanest atmosphcrcs uliuitlly
raises p at 0.6943 pm to at least l0-7 cm r.
84.2 The Laser Range Equation,
Average irradiance at range r (for a direct circular
beam) is the total power in the beam at ,' divided by
the area of the beam at ,'; likewise, the radiant exposure
in a nonturbulent medium is the total energy in
the beam at r divided by its total area.
' @e lt' | .2'1 Q e-r
(Eq 88)
'
z=----f--|T=
la+r-Ol
nl " I
L - _ t
n"-lt | | j1 /'la-l.r r
H = --Y--------,-t'- = :::29:-
" l
la+rbl'
? |
L - J
(a+rQ>'
(Eq 89)
NOTE l: These formulas are accurate only for small 0
values: the accur,rcy is belter than l% tbr angles less than
0.l7rad (10') and better than 5% tbr angl€s less than
0.37 rad (21').
NOTE 2: For a Gaussian beam the mdximum iffadiance at
the beam axis is calculatcd using Eq 88, if a and S are
defined at the l/e points of maximum irradiance.
* Adrpted ironr C.'l 1l .'J ltu:ar.l! kt Hutlth ft1'n Lu:ttr
Rudiution, U.S. Depanment of the Afmy Technical Bulletin
I'B-MED-524 {1985). S€€ Applndix C, References for Control

APPENDIX
NOTE 3: For rectangular or elliptical beams see 84.7.
Example I7'. Find the radiant exposure at I km
(105 cm) from a O.lJ Q switched ruby laser (pulse
length = 20 ns) which has a beam div€rgence of
I mrad (lfr rad) and an emergent beam diameter of
0.7 cm. Using !t = l0-7 cm-r to provide a worst case
estimate,
"
'J =
, ,rrn , ,,_fl0 ' )rtd )
jj:j-:::j=-
(0.7 + 1t05;116-111:
_ (1.27) (0.1) (0.ee)
(0.7 + 100)2
= 1.25 x l0-5 J . cm-2
84.2.1 Norninal Ocular Hazrrd Distance
(NOHD).
If the atmospheric attenuation coefficient is
neglected, a worst case estimate of the NOHD
(rMoflD) for Example l7 can be calculated from:
1
rNoHD =
6
o [,_ I
=# h/+*P -.'J
( 5.M km
84,2.2 Range Nomogram, Fig, 86.
The range nomogram in Fig. 86 (which includes the
attenuation coefficient) can also be used to determine
rNoHD. For the values given in Example 17, draw a
line between l00mJ and l.0mrad. This line intercepts
the "lntegrated Radiant lntensity" scale at
approximately 0.13 MJ ' s.'. A line is then drawn
from the above point to 0.5 lrJ.cm-z on the "Radiant
Exposure" scale, intercepting the "Range" scale
at 4.9 km for a clear day and 4 km for a hazy day.
84,3 Bearn Diameter.
The minimum beam diameter. for a small 0 at range
r, is given by F4 84:
Dt=a +Qr
Example 18: Find the diameter of a laser beam at
l km where the emergent beam diameter is lOcm
and the beam divergence is 0.1 mrad.
66
Dr = l0 cm + (l0r rad) (105 cm)
P1
E=
tD cosO"
or
H=
and
= l0+ l0=20cm
84,4 Diffuse Refl ections.
The reflected irradiance or radiant exposure for a dif.
fuse reflector (for rl :> D.) is given by
--;4-
pr O cos0"
--;i-
{@=,,.,".
'(rr)(10-")
(Eqs Bl0
Example 19: Find the maximum rcflected mdiad
exposure at a point along the beam axis of a 0.1 I
laser, lOm from a diffuse matte of reflectance 0.6 .
(cos 0l = 1).
H_
(0.1J)(9.6),
= 1.9t x tga J.cm-2
(3.14) (10' cm)'
Example 20: Find the minimum safe viewing distane
for looking at a diffuse target having a rcflectivity
P;, = 0.9 from a laboratory Ar laser with O = 2W and
d = 2 mm (assume a l0 s exposure duration). (fhis is
also the border of the NHZ, see Fig. B4). The emergent
beam irradiance is 6^3.7 W.cm-2 which ir
greater than the 6,8 W 'cm-' maximum permissible
irradiance incident on a 100 percent diffusely
reflecting surface for a lOs exposure duration (s€e
TableBl). It is therefore concluded that 4vflz must
be greater than Dllohin and intmbeam MPEs apply.
Hence, the l0 s MPE is I x l0-3 w'cm-2 (Table 5
or Fig. 4) and the expression for rpsT can be found by
reananging Eq Bl0. Hence
(Eq BI0a)
Figure 86 may also be used to determine this distance
graphically.

84.5 OptlcaUy Alded Vlewing.
The ratio, G, of the radiant exposure or inadiance at
the retina when viewing is aided by an optical system,
to that received if the eye were unaided, is
defined by the equations given in B4.5.1 and 84.5.2.
84,5.1
Intrabeam viewing and specular reflection (or diffuse
spot unresolved by eye and optical system):
D7
Q = --l for d"2D"
a;
ano
D2
G=-s=P' for d"3D"
t);
84.5.2
Indirect viewing of a diffuse reflection, extended
objects only (that is, the object subtendsan
angle
greater than 0.6 mrad when magnified):
D1
C = -
and
3lford,2D"
DI
C = =j ^ =lford"3D.
P'Di
(Eq Bl l)
(Eq B l2)
(Eq B 13)
(Eq B 14)
NOTE: The ratio, G, is affected by the optical transmission
of the instrument, but this is normally insignificant. If this
is not the case, then this factor should be in the numera(ors
of Eqs Bll through B14.
Example 2l: Viewing the diffuse reflection of the
laser flash of Example l9 through a pair of l0 x 50
binoculars (that is, P = l0 and D., = 50 mm). Determine
the relative hazard io the viewer's eyes for night
viewing. Since the exit pupil is D,/P = 0.5 cm,
estimating 4 to be 0.7 cm and using Eq B13 yields
G= - !5cm)2 - =-_4 _ =0.r,
(10)2 (0.7 cm)2 (100) (0.49,
The hazard is equiyalent to a comeal radiant exposure
on the naked eye of: (0.51)(1.91 x l0-8 J .cm-2) =
9.7 x l0-q J . cm-2.
Emmple 22: Viewing a specularly reflecled beam at a
distant point where the beam radiant exposure measurcs
2 x lO-e J.cm-2. If an operator were to view
the beam through a pair of 7 x 50 binoculars, (and the
beam diarneter is larger than the objective diameter),
what would be the relative hazard compared with
unaided viewing? The magnifying power, P, of the
APPENDIX
binoculars is 7 and, if inrierted in Eq Bl2, will pro.
vide the simplest solution:
G=p2=72=49
Thus, the operator would be viewing a level 49 times
greater than with the naked ey^e, or a com€al radiant
exposurc of nearly l0-' J . cm-'.
84.6 Scanning Lasers.
The comeal radiant exposure for a single exposure
from a scanning laser beam is given by Eqs B 15 and
Bl6. (Repetitive-pulsed exposures depend upon
geometrical considerations, scan rate and frame rale.)
.- l.ZlQen' de ^
a =,, *6 ;d- ror4>(4+/'o)
ot
for d" < (a + r$)
(4 + ro) 0's0")
(Eq B l5)
(& B16)
The applicable MPEs depend upon the repetitive
nature of the exposure and the exposure duration of a
single pulse, where
r=@!-!$ for d. < (a + 16)
rJ U.
or
|.27 Qe-Y'
d"
1= _ for d" > (a + rO)
ruur
and the prf is 5 if each scan passes over the eye.
(Eq B l7)
(Eq B 18)
Example 23: Find the exposure of a scanning He-Ne
laser system having the _following
pararnete$:
a=0.lcm, Q=5 x 10" rad,

o
APPENDIX
'
0,1+(200)(5 x t0-3) l.l
(?oo) (30) (o.l) 600
t = - = -
= 1.85 x l0-3 s
Step 3. The radiant exposure per pulse as found from
Eq Bl6 is:
(r.27) (10 x lo-1)(l)
" ,. =
(oJJ l x2oox3oxoJ )
=l.92xl0sJ'cm-2
Step 4. The average irradiance at the comea is
Eav = H . S = (1.92x l0-5) (30)
= -5.76 x 10{ W cm-2
Step 5. The applicabte MPE per pulse for a 0.25 s
exposure is determined by the cumulative exposure of
almost eight pulses:
MPE/Pulse = n-r14(MPE)
= r-rla11.g tl/a) x lo:3 J .cm 2
= 8r/4(1.8) (1.82 x 1fr3)3/a x lf3 =
= (0.s95) ( 1.6 x l0-s) =
=9.44xt06J'cm-2
The total radiant exprosure for a 0.25 s exposure duration
must be compared with the MPE for a pulse train
of the same duration. The MPE for the pulse train
dumtion is:
MPE/Train = a (MPE/Pulse)
(S) (9.44 x tg o1J cm-?
= 7.55 x 10-5 J cm-2
This total radiant exposure is equal to the producl of
the single pulse exposure and the number of pulses,
or
11r,, = n (H/Pulse)
=8(1.92x10-5)
= 15.4 x l0-5 J cm-z
Since the MPE for a 0.25 s exposurc duration is less
than the radiant exposure for a train of pulses of the
68
same duration, the exposure is not permissible for
momentary (uninrcntional; viewing.
84.7 Axial Beam Radiant Exposure for R€ctangu.
lar and Elliptical Beams.
The axial beam radiant exposure for a rectangular or
elliptical beam can be calculated using modifications
of Eqs 88 and 89.
For an elliptical beam
1.27 @ e}' (Eq Bl9)
(b + ror) (c + r02)
-. t .27 Oe-P'
'' H = +
(h + r0r) (c + r02)
For a rectangulat beam (or a
bt=tt)
E=
H =
@ e+'
(br +r0r)(cr +r+2)
Qc-P'
(h1+i'q'116'a,.qr;
(Eq 820)
squarc beam, wherc
(Eq B2l)
(Eq B22)
Example 24: Find the average beam irradiance at
r = 20 m for a CaAs laser illuminator with the following
parameters: @=2W; br =2cm;cr = l3cm;
0r = 5l mrad (3"); 0z = l7 mrad (l').
Using Eq B2l:
(2W)(l)
[2 cm + (200O cm) (0.05 radiJ
.
[1.3 cm + (2000 cm) (0.017 rad)
E=
t
=5.4x lOa w cm-2
( r04) (35.3)
B4.E Nominal Hazard Zone (NHZ).
Examples 25 and 26 show methods used for determining
lhe NHZ for medical and industrial laser
applications.
E,rample 25: A 50 W cw Nd:YAG (l'= 1.064lrm)
surgical laser is used in an operating suite. It can be
used either with an endoscope (where the beam is
contained within the patient whenever ihe laser
operates). or with a handpiece having a focal length
of l0cm and emergent beam diametsr, a, of I cm
(f /a) = l9 Determine the NHZ.

lO
,,.0 L when the laser is operated with rhe endo-
, scope lhe NHZ is limitcd to the endoscope.
Step 2. Delermine rNHz. When the handpiece is used
the beam would normally be directed downward
toward the patient and the diffuse reflection zone
from a worsFcase reflection from an anodized instrument
(p=O.9) could be calculated from Eq. Bl0a.
Assuming a worst case viewing angle, (0u = 0"),
(0.9x50x1)
r(5x103)
=./2364 = 53.5 gm
Although one could attempt to use TableBl, the
focal spot size would vary and is nol generally
known; hence Eq. Bl0a provides the only approach,
and in any case will always provide the most conservatlve
answer.
Step 3. Determine ry6pp. lf the handpiece could be
directed away from the patient, determine r*op for a
I0 s exposure where the MPE(E) is 5 mW cm-z:
I
0
ti
l0
I
^ fr2i @
Y cm
t"a
| .27 A
MPE "...
1.27 (so)
fxltt-
=ll?6cm=ll.3m
(Eq B23)
This value of 11.3 m becomes the dominant value for
determining the radial extent of the NHZ if rhe beam
can be reasonably expected to be accidentally or
intentionally directed toward people. In normal surgical
use, such lasers are not intentionally operat€d
except when directed at the target tissue. Hence the
I1.3 m distance shoutd be used to define the region
wherein eye protection and other control measures
(e.g., area,/entryway controls) arc administratively
APPENDIX
Example 26: A manufacture uses a 1000 W (l kW)
cw CO2 laser for a cutting process. The beam is
routed through a beam conduit (pipe) tb a final work
station where the beam size has expanded to a diameter
of I inch (2.54 cm). A s-inch (l2.7cm) focal
length lens is used to focus the beam. The lens determines
the extent of the NHZ. Fis. 87 shows the
arTangement.
Step [. Determine the NOHD (i.e., the distance along
the axis of the focal cone to that point where the
beam irradiance is equal to the MPE). Although this
system will operate almost continuously during a day,
unintentional exposure to the direct beam could be
reasonably expected to occur for up to lOs. The
l0 s MPE is 100 mW' cm-'. The F-number (//a) of
the lens is
f ta = (12.7) t(2.s4) = s
and the divergence (+) of lhe unterminated beam
from the focal point is
l l
0= _ ===O-2rad
f-numDer f
The NOHD can be found from Eo. 823
I
rpouo = T
, a [',l;m xxTnri#i;:ti:i', *i#]""::"$'l:
protection is mandatorv.
1.27 Q
MPE
, -,ftr.ztx-iii
- --- \ cm
ll)
= 5(l l3) = 563 cm = 5.63 m
This is the value used for points along the beam axis
unless the beam is always terminated.
Step 2. Determine the diffuse reflection hazard distafice
\,147. The reflectance p is probably far less
than 209o , and from Eq B lOa and a worst case viewing
angle 0u of0",
@ pr cos 0u
(TXMPE)
" t, loooro-zr, l )
= \ cm
*fif]'-
=\bJ/ =lf cm

o
o
APPENDIX
Step 3. Determine the NHZ associated with a specular
reflection from the workpiece. Assume pr = 0.2
(worst case), rysT for a specular reflection is found
ftom:
I
rNHz =
6
l.n Q pL
cm
MPE
= ZJZ Cm = 2.5). m .
The beam diameter at this distance is
DF Q rum
= (0.2)(252)
cm
= 50.4 cm
The NHZ is therefore well defined near the beam
path.
Step 4. Determine the operator exposure, After
defining the NHZ, one should consider long-term
unavoidable exposure of the skin of the operator.
Since the operator is requircd to manually load and
unload the parts to be processed, there is a finite pmbabiliry
of exposure to scattered energy (fmm diffuse
reflections) to the arms and face for periods up to
8 hours. The MPE for the skin must be reduced for
large-area long-term exposures as described in 8.4.1.
Assuming that the unprotected areas (A") of both
arms is approximately 400 cm2, the corresponding
MPE is:
MpE= -!q@ - 10'000
=25mW.cm-2
As 40O
This value can be used to calculate the distance along
the beam axis of the focal cone to the point where the
inadiance and the MPE are equal. Hence,
't0
I
0.2
fl.27X 1000x0.2)
-cm
I
I
0.2
ffi"
= -lG"oet tot
0.2
=ll27cm=ll.3m
But, let us assume that the beam is blocked by a dil
fusely rcflecting surface located et a distance d
200cm from the focal point. At this distance th
beam diameter is Dy=$r = 0.2(200) =,10 cm. On
can approximate the diffuse rcflection from a 100{
diffusely reflecting surface using Eq Bl0a. Thus th
distance (4ys2) from the reflecting surface to tlt
point at which the inadiance is equal to the MPE cal
be determined.
^/ p1

O m*B.'".:frffi:: r# $":;ffi:JT'lT[
,
I
initial beam diameter (d), or
Dr -a
O =
-
for small 0
r
Example 27: Determine the maximum beam inadiance
and the beam irradiance averaged over a 0.7 cm
diameter aperture for a Gaussian beam from a 5 mW
laser with a 0.8 cm beam diameter.
Step l. Determine the maximum beam irradiance
from
^ l.na ...
E-= =- W'Cm
/l tTvS v ln J\
(0.8)2
=9.9x10-rW.cm-2
-
Step 2. Determine the
averaged over a 0.7 c;n di
r lD. l
- 4P, -
l. Io.l
8,,= -'-"'- maximum beam irradiance
4meter apedure from
I
" ll-e
ND:, I
L
.l
- r -lorl ln.tl'r
(4X5x l0-r)
= """"""'--- l.
I
t|-e I
n (0.7)' L _l
= l.3o x lo-?
lr-0.+osl
= 6.95 xl0-3 W . cm-2
Example 28: Detemine the appropriate beam diameter
to be used in hazard analysis for a laser beam
diameter of 0.3 cm specified at the I tez points. The
laser is further specified to be single-mode and Caussian.
Since the beam is Gaussian, the beam diameter
measured at the I le2 points is greaaer by a factor of
! 2 times. Hence
n1
a =:=. =0.21 cm
12
Example 29: Find the approximate beam diameter of
a Gaussian laser beam having a total output power of
5 mW and a measured power of I mW through a
0,7 cm diameter apelture. The approximate beam
o'uttttt ,a) can be found from Eq 824. Hence,
P
-
---f---T o.72
r"lr-ll
[ ]J
-1,"1'r
_" lD,l I
' l
= 1.48
cm
APPENDIX
Example 30: Find the maximum percentage of the
total power P" of a 3 mW HeNe laser that will pass
through a 7 mm diameter apefture if the beam diameter
specified al the I /e2 points is 1.6 cm.
The fraction of the total power which passes through
an apenure ofdiameter Do is given by
b€am diameter is specified at the l/e2
= 1.6 l ,'12 Since the
points, D.
= l.l cm and
. Int l"
p -
| l-i-il I
t"t
#=lr-" l=a.333
ro L I
and the total power passing through the apenure will
be
P"=O.333 P" = (0.333) (3 x l0j)
=lxl0-3w

APPENDIX
Table Bl
Typical Diffuse Reflection Cases for Visible Radiation (l' = 0'4 to 0'7 pm)*
Pe.missible Laser Beam Radianl Exposure lncidenr on a Diffusely
Reflecting Surface, MPE x [/p(J 'cm-2]
Exposure
Duration, ,
(r)
MPE at Comeal
(J sar 'cm-2)
Limiting
Angle, a;" + Reflectanc€ (P) = 100% Reflectance (p) = 50% Reflectance (p) = l(,{
(l)
(2)
(3)
l0-4 l.O x l0-? 8.0
l0-8 2.2 x ltJ-? 5.4
10-7 4.6 x l0-'
17
10-{ 1.0 x I0.r 2.5
l0-r 2.2 x l0-'
l0r
t0
4.6 x l(rr 2.2
l I0
10 to loa 22
l 1.0 3.6
f o-'
10-
2.2
5.1
9.2
l5
24
| 4.6
(4)
3.1 x l0-2
6.8x102
1.5 x l0-l
3.1 x l()-
r
6.8 x l0-l
l_f
3.1
6,8
15
1t
68
(5)
6.3 x l0-2
t-4 x l0-l
2.9 x lfr
6.3 x l0-r
1.4
2.9
6.3
l4
29
63
t40
* For wavelengths between 0 7 and t.4 pm, use the appropriatc correction factors given in 8 5
t Sec Fig. 7 for a graphic presentation of these values.
+ For extended sources, angular subtense > o min (see 8.1)
72
(6)
3.1 x l0-r
6.8 x l0'l
1.5
6.8
l5
3I
68
r50
310
680
f.

,O
,o
,o
Fig. B1
Intrabceo Viowing - f,iircct (Pdnary) Bc.n.
FLAT SURFACE REFLECTION
CURVED SURFACE REFLECTIOiI
ftOTE '
': ToTIL EEAM DISTANCE FROlii LASER TO EYE
(OIRECT PLUS SgCONOARY )
Fig. 82
Intrabcan vicwing - Spcctlarly Rcficcrxl
(Sccondery) Bcan.
Fig. B:l
Ertcadcd Sourcc Vicwing - Nonaally IXfwc Rctlcctiotr.
APPENDIX
73

I
t
APPENI)IX
l--rxe6e---.1
Fig. B{
Ersmpl6 of Ulc of kscr Rrngc Equltiol for
Dctennining Nomind llazard Disteacc.
Fi3' 85
Nominal lfuzard Zottfor r Ditfulc ReflEctiol.
rnoxo =* (#r;'"-"1
rNoHo=(t)(#J'"
(\| 4 f""
I ma t;gP--, (MuLrliiloDE)
rrom =
1 r.,o f o.lua
[T fu-ueeJ (slNcLEMooE)
/ p tDCosO 1l/2
rNHz =F;ffFE_/

ENERGY BEAM
OUTPUT DIVERGENCE
'oooT 'l
(mJ) (mr)
I I
,.ol ,.1
+ I
I I
"+ "+
f +
'f I *' I
f + I
",1 "* I
POWER
OUTPUT
(mlV)
INTEGRATEO
RADIANT
INTENSITY
(MJ/sr)
o.ol
RADIANT
INTENSITY
(MW,/sr)
RANGE
(km)
LASER RANIGE
EOUATION NOMOGRAM
Fig. 85
hscr Rangc Equstion Nomogrsn,
APPENDIX
RADIANT
EXPOSURE
lpJtcnzl
IRRADIANCE
(yw/cmz1

o
APPENDIX
't6
UJ
(L
d
F
x
9 J
(r
lrJ
CN
J
(\l
o(J
z
o F()
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9l
rl
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Information and References for Sections 3 and 4
Cl. Alternate Labeling
Some laser equipment manufactured outside of the
USA may conform to requiremenls of the IEC
Publication 825, "Radiation Safety of Laser
Products, Equipment Classification, Requircments
and User's Guide." The IEC 825 label style (shown
in Fig. Cl and C2) is different ftom that required by
this standard and those specified in the Federal Laser
Product Performance Standard.
C2. References for Sections 3 and 4
Control of Hazards to Health from Laser Radiation.
U.S. Depanment of the Army Technical Bulletin
TB-MED-524, June 1985. Available from National
Technical Information Service, Springtield, Va.
?.216t.
Electronic Product Radiation and the Health
Physicist, Proceedings of the Fourth Aonual Midyear
Topical symposium; 1970. Washington: U.S.
Depafiment of Health, Education, and Welfare;
Bureau of Radiological Health, Division of
Electronic Products; 70-26. Available from National
Technical Information Sewice, Springfield, Va.
22161.
Evaluation of Commercially Available Protective
Eyewear. Washington: U,S. Department of Health,
Education, and Welfare; Publicarion (FDA) 79-808G1
1979 May.
Goldman, L., Rockwell, R. J., Jr. Lasers in
Medicine. l97l; chapter ll; New York: Gordon and
Breach Science Publishers, 197 | .
Goldman, L., Rockwell, R. J., Jr., Homby, P. Laser
l,aboratory Design and Personnel Protection from
High Energy Lasers. In: Handbook of Laboratory
Safery. N.V. Steere, ed; Znd ed. Clevetand: The
Chemical Rubber Company; l97l: 381-389.
Intemational Electrotechnical Commission Standard
Radiation Safety of Laser Products, Equipment
Classification, Requirements and Users Guide. IEC
Publication 825: Geneva Switzerland: 1984-
APPENDIX
Laser Health Hazards Control. U.S. Department of
ihe Air Force Manual AFM-l6t-32, 1973 (or latest
revision thereof). Available from National Technical
Information Service, Springfield, Va. 22161.
Laser Product Performance Standard. Code of
Federal Regulations, Title 21, Subchapter J, Part
1040. 1979.
Laser Products: Amendments to Performance
Standard; Final Rule. Code of Federal Regulations,
Title 21, Parts lff)o and 101(), Federal Register, Aug.
20, t985.
Marshall, W. I. Hazard analysis on gaussian shaped
laser beams. Joumal of the American Industrial
Hygiene Association. 4l (8): 547-551; 1980 Aug.
Rockwell, R. J. and Moss, C. E. Optical radiation
hazards in laser welding processes Pan I:
Neodymium - YAG Laser. The Joumal of the
American Industrial Hygiene Association. 44(8);
572-579; 1983 Aug.
Rockwell, R. J., Jr. Ensuring safety in laser robotics.
Lasers and Applications. 3( I l);65-69; 1984 Nov.
Sliney, D. H. Evaluating health hazards from military
lasers, Journal of the American Medical Association.
214(6): 1047-1054; 1970 Nov.
Sliney, D. H. Laser Protective Eyewear. In:
M. L. Wolbarsht, ed. Laser Applications in Medicine
and Biofogy. New York: Plenum Prcss; 1974: v.2,
chapter7,pp.223-240.
Sliney, D. H. Wolbarsht, M. L. Safety with Lasers
and other Optical Sources. New York: Plenum
Publishing Co; 1980.
Swope, C. H. The eye - protection. Archives of
Environmental
Health. l8(3): 428-433; 1969 Mar.
Guide for the Selection of l,aser Eye Protection.
Toledo OH: Laser Institute of America: 1984 Mav.
77

APPENDIX
7lr
SYMBOL AND BORDER. BLACK
BACKGROUND 'YELLOW
Fig. Cl
IEC-825 (1985) Warning labcl - lhzard S),cbol'
LEGEND AND
BACKGROUND
BORDER'BLACK
,YELLOW
Fig. C2
IEC-E25 (19E5) Warning hbcl - Label for
Erplanaory Wording,
ffir

; O 4penoi*o
Guide for Organization and Implementation
of Laser Safety and Training programs
The extent to which the various parts of the following
guide are applicable to a specific organization
depends on the magnitude of the potential laser
hazards within that organization. However, it is
essential that each laser safety program include
sufficient education of personnel in laser safety.
Dl. Responsibility and Authority ofLaser Safety
Officer (LSO)
Dl.l General. The Laser Safety Officer (LSO) may
be designated from among such personnel as the
radiation protection officer, industrial hygienist,
safety engineer, Iaser specialist, laser operator, etc.
The LSO may be a user if there are very few laser
operations or if the class of lasers and potential
, o lxffi lli"i'il; *i-',"'"? ,ffi"T,L :H;,'il:
require a full-time effort. The LSO will effect the
knowledgeatrle evaluation and control of laser
hazards, and have the authority to monitor and
enforce the control of laser hazards. In addition to
the responsibilities described in Section 1.3.2, the
LSO's authority may include, but is not necessarily
limited to, the responsibilities of operarion specified
in Dl.2 through D1.8. The LSO will be trained in
accordance with D6.
Dl.2 Consultative Services, The LSO will provide
consultative sewices on laser hazard evaluation and
controls and on personnel training programs. Such
eyaluations will include electrical and other nonradiation
hazards of lasers
Dl.3 Regulations. If a Safety Committee does not
exist, the LSO may establish and maintain adequate
regulations for the control of laser hazards.
Dl.4 Authority. The LSO will have rhe authority
^
to suspend, resftict, or terminate the operation of a
I ol*"i."liflTJ#,TJ:,[Hr she deems that
raser
APPENDIX
Dl,5 Records. The LSO will ensure that rhe
necessary rcf,ords required by applicable govemment
regulationsarc
maintained. The LSO will also
submit to the appropriate medical officer the
individuals' names that are obtained in accordance
with D1.4, D4.5, and D5.3. The LSO will ensure that
the appropriate records are maintained indicating that
applicable medical examinations have been scheduled
and performed and that appropriate training has been
provided.
Dl.6 Surveys and Inspections. The LSO will
survey by inspection, as considered necessary, all
areas where laser equipmenr is used. The LSO will
also accompany regulatory agency laser equipment
inspectors, such as those representing OSHA,
FDA/CDRH, state agencies, etc., and document any
discrepancies noted. The LSO will ensure that
correciive action is uken where reouired.
Dl.7 Accidents. On notification of a known or
suspected accident resulting tiom operation of a laser,
the LSO will investigate the accident and initiate
appropriate action. This may include rhe preparation
of repons to applicable agencies. (See D7[7] for
federal reporting requirements references.)
Dl.8 Approval of Laser Syslem Operation.
Approval of a laser or laser system for operation will
be given only if the LSO is satisfied that laser hazard
control measures are adequate. These include special
operating procedures for maintenance and service
operations within enclosed systems, and operation
procedurcs for Class 3 and 4 systems. The
procedures will include adequate consideration to
assure safety from electrical hazards.
D2. Deputy Laser Safety Officers
If necessary, a Deputy Laser Safety Officer will be
appointed by management. The Deputy Laser Safety
Officer will perform the functions of the LSO when
the latter is not available.

APPENDIX
D3. Safety Committee
D3.l Necessity. If wananted by the magnitude of
the potential hazards of laser operations within lhe
organization, a Safety Committee may be formed.
D3,2 Membership of Laser Saf€ty Committee,
The membership may include individuals with
expertise in laser technology or in the assessment of
laser hazards. Management may be included in the
membership. Examples of members include, but are
not limited to: technical manager, LSO (or other
representatives from the safety department),
physician and user representatives.
D33 Policies and Practices. The committee will
establish and maintain adequate policies and
regulations for the control of laser hazards and
recommend the appropriate laser safety training
programs and materials.
D3.4 Standards. The committee will maintain an
awareness of all applicable new or rcvised laser
safety standards. This may rcquire liaison with
regulatory agencies, either directly or through
representatiYes.
D4. Responsibility ofthe Laser or Las€r System
Supervisor
D4.l Prerequisite. The supervisor will be
knowledgeable of education and training
requirements for laser safety, the potential laser
hazards and associated control measures for all lasers
and laser systems, and all procedures pertaining to
laser safety at locations under the supervisor's
authority.
D4,Z Indoctrination. The supervisor will be
responsible for the issuance of appropriate
instructions and training materials on laser hazards
und lhcir control to itll pcrso[ncl wh() may work with
lasers that are operated within the supervisor's
jurisdiction.
D4.3 Laser Hazard Control. The supervisor will
not permit the operation of a laser unless there is
adequate control of laser hazards to employees,
80
visitors, and the general public.
D4.4 Individuals Scheduled to Work with Lasers'
The supervisor will submit the names of individuals
scheduled to work with laser$ to the tSO and, in
addition, will submit information as requested by the
LSO for medical surveillance scheduling and training
completion (see Table Dl).
D4.5 Reporting of Known or Suspect€d
Accidents. When the supervisor knows of or
suspects an accident resulting from a lasef operated
under his or her authority, the supervisor will
immediately notify the LSO or other designated
authority.
D4.6 Medical Attention. If necessary, the
supervisor will assist in obtaining aPpropdate
medical attention for any employee involved in a
laser accident.
D4.7 Approval of Laser System Operation. The
supervisor will not permit op€ration of a new or
modified laser under his or her authoritv without the
approval of the LSO.
D4.8 Approval of Planned Installation,
supervisor will make sure that plans for
tne
laser
installations or modifications of insiallations are
submitted to the LSO for approval.
D4.9 Operating Procedures. For Class 3a,
Class 3b or Class 4 lasers and laser systems the
supervisor will be familiar with the operating
procedures and ensure that they are provided to users
of such lasers.
D5. Responsibility of Employees Working wlth or
near Lasers
D5.l Aufhorizalions. An employe€ will not
energize or work with or near a laser unless
airthorized to do so by the supervisor for that laser.
D5.2 Compliance. An employee will comply with
the safety rules and regulations prescribed by the
supervisor and the LSO. Thi employee will be
familiar with all operating procedures.
rii

D5.3 Accident Reporting. When an employee
,l operating a laser knows or suspects that an accident
has occurred involving that laser, or a laser operated
by any other employee, and that such accident has
caused an injury or could potentially have caused an
injury, he or she will immediately inform the
supervisor. If the supervisor is not available, the
employee will notify the LSO.
,l
D6. Training
D6,l General. Training will be provided to each
employee routinely working with or around lasers
above Class 2. The level of naining wi[ be
commensurate with the degree of potential laser
hazards.
D6.2 Laser Safety Training program Topics,
Topics for inclusion in a laser safety rraining program
may include, but are not nesessarily limited io. the
following:
g].::'personnel
roudnelv working on or around
(a) Fundamentals of laser operation (physical
principles, construction, etc.)
(b) Bioeffects of laser radiation on the eye and
skin
(c) Relations of specular and diffuse reflections
(d) Nonradiation hazards of lasers (electrical,
chemical, reaction by-products, etc.)
(e) Laser and laser system classifications
(f) Control measures
(g) Overall management
responsibilities
and employee
(h) Medical surveillance practices (if applicable)
(D CPR for personnel servicing or working on
lasers with exposed high voltages and/or the
capability of producing potentially lethal
electrical cunents
(2) For the LSO or other individual responsible for
the laser safety program, evaluation of hazards, and
implementation of control measures, or any others
directed by management to obtain a thotoueh
knowledge of laser safety:
(a) The topics in D6.2 (l)
(b) Laser terminology
(c) Types of lasers, wavelengths, pulse Ehapes,
modes, power/energy
(d) Basic radiometric units and
devices
APPENDIX
measurcment
(e) MPE levels for eye and skin under all
conditions
(fl Laser hazard evaluations, range equations,
and olher calculations
D7. References
lll Smith, J. F., Murphy, J. J., Eberle, W. J.
lndustrial Laser Safely Program Management.
Poughkeepsie, New York: IBM Corp, System
Products Division.
[2] Smith, J. F. Safety Programs and Formal
Training. In: Sliney and Wolbarsht. Safety with
Lasers and Other Optical Sources. New york:
Plenum Press; 1980: chapter 25-
[3] LIA Laser Safety cuide. Laser Institute of
America, 12424 Research Parkway, Orlando, FL
32826.
[4] American Confcrence of Govemment
Industrial Hygienists. A Cuide for Control of Laser
Hazands. ACGIH, P.O. Box 1937, Cincinnati. Ohio
45201.
[5] L"aser Institute of America. Laser Safety
Training Package (8o-slide ser wirh audio-taped
cass€tte on industrial laser safety). Available from
Laser Institute of America, 12424 Research Parkwav.
Orlando, FL 32826.
[6] Shon courses and other haining programs and
materials on laser safery are offered by the following:
Engineering Technology, Inc. 601 A Lakeair Drive,
Waco, Texas 76710.
Laser Institute of America, 12424 Research Parkway,
Orlando, FL 32826.
Rockwell Associates, lnc. P.O. Box 43010
Cincinnati, Ohio 45243.
[7] Manufacturer's accident reponing
requirements arc detailed in the Code of Federal
Regulations, 2l CFR Subchapter J Part 1002.20.
8l

APPENDIX
82
Table Dl
Recomrnended Training for LSOs and Employees
(Including, but Not Limited to' Operators'
Maintenance Personn€l, tnd S€rvice Technicians)
Routinely Working with or around Lasers
Method of Training*
Manufacturers Cuidc
and Operating Manuals
Safety Guide Literature (3)
Film and Slide/Audio
Programs (5)
Laser Safety OrientatjoD$
Shon.Term Course (6)**
Review of Applicable
Standards
ry'a not applicable
R recommended
SR strongly recommended
R S R
a +
nla nla
nla n/a
nla nla
Highest-class Laser
2al) 3a 3b 4 LSOsf
SR SR SR n/a
SR SR SR SR
R S R S R S R
nla R SR SR
flla nla R SR
nla nl^ n/a nl^ a SR
The numbe.s in parentheses refer to the corresponding numbered items in the reference list, D7
where the suggested training vehictes for the L.so a.e deemed inappropriate for reasons of very low potential
hazards or very limited use of lasers, substitute training vehicles may be used, Regardless of the training vehicles
used, the LSO'S training musr enable him or her to fulfill the requiremenls and responsibilities of an LSO as
outlined in Dl.l through D1.8 and Section I 3 for all lasers under the LSO'S jurisdiction-
Although education is not required for class I and 2 lasers, lhe safety cuide Literature provides a low-key basic
guide to the general topic of laser safety and is suggested herc for consideration to the usem of this standard.
A Laser Safety orientation course may include the previously mentioned vehicles. Because of the greater potential
hazards from Class 3b and 4 lasers, the duration of the course would be from several hours to a day or two. This
raining may be conducted by outside specialists if not available intcmally'
shon-rcrm courses may run from a day or lwo to any length required. Bccause of the high level of potential hazards
to both eye and skin for class 4 l.$ers. the training should be complete and cover all applicabte topics described in
D6.2.

sl
Appendix E
Medical Surveillance
El.0 Purpose of Medical Surveillance
The b;uic reasons for prforming medical surveillance
of personnel working in a laser envimnment are
the same as for other potenlial health hazards. Medical
surveillance examinations may include asscssment
of physical firness to sately perfbrm assigned
duties, biological monitoring of exposure to a specilic
agent, and early detection of biologic damage or
effect.
Physical fitness assessments
are used to determine
whether an employee would be at increased or
unusual risk in a panicular environment. For workers
using laser devices, the need for this type of assessment
is most likely to be determined by factors orher
than laser radiarion per se. Specific information on
medical surveillance requirements that might exist
because of other potential exposures, such as toxic
gases, noise, ionizing radiation, etc, are outside the
scope of this appendix.
Direct biological monitoring of laser radiation is
impossible, and practical indirect monitoring through
the use of personal dosimeters
is not available.
Early detection of biologic change or damage presupposes
that chronic or subacute effects may result from
exposure to a particular agent at levels below that
required to produce acute injury. Active intervention
must then be possible to arrest further biological
damage or to allow recovery from biological effects.
Although chronic injury from laser radiation in the
ultraviolet, near ultraviolet, blue ponion of the visible,
and near infrared regions appears to be theoretically
possible, risks to workers using laser devices are
primarily from accidental acute injuries. Based on
risks involved with current uses of laser devices.
mcdical surveillance requirements that should be
incorporated into a formal standard appear to be
minimal.
Other arguments
in favor of performing extensive
medical surveillance have been based on the fear that
repeated accidents might occur and the workers
would not report minimal acute injuries. The low
number of laser injuries that have been repofted in the
past ?0 years and the excellent safety records with
laser devices do not provide suppofi to this argument.
E2.0 Medical Examinations
E2.l Rationale for Examinations
APPENDIX
E2,l.l Prcassignmcnt Medical llxaminations,
Except fbr examination following suspected injury,
these are the only examinations required by this standard.
One purpose is 1o establish a baseline against
which damage (primarily ocular) can be measured in
the event of an accidental injury. A second purpose
is to identify cenain workers who might be at special
risk from chronic exposure to selected continuouswave
laseni. For incidental workers 1e.g., custodial,
military personnel on maneuvers, clerical and supervisory
personnel not working directly with lasers)
only visual acuity measurement is required, For laser
workers medical histories, visual acuity measurement,
and selected examination Drotocols are
required. The wavelength of laser radiation is the
determinant of which specific protocols are required
(see 82.2). Exanrinations should be performed by, or
under the supervision oi an ophthalmologist or other
qualified physician. Cenain of the examination protocols
may be performed by other qualilied practitioners
or teshnicians under the supewision of a physician.
Many ophthalmologists may prefer to perform
more thorough eye examinations to assess total
visurl l'unction as opposed to limiting examinalions
to those areas that might be damaged by laser radiation
at panicular wavelengrhs, Some employers may
find il advantageous to offer these more thorough
examinations to their workers as a health benefit. For
example, certain of the additional examinations, such
as lonometry, may be of value in detecting unknown
disease conditions, in this case glaucoma. Even
though this type of problem is untelated to work with
lasers, appropriat€ medical intervention will promote
a healthier work force. Although chronic skin damage
f'rom laser radiation has not been reported, and
indeed seems unlikely, this area has not been adequately
studied. Limired skin examinations are suggested
to $erve as a baseline until future epidemiologic
study indicates whether they are needed or not.
82.1.2 Periodic Medical Examinations.
Periodic examinations are not required by this standard.
At present no chronic health problems have
83

APPENDIX
been linked to working with lasers. Also, most uses
of lasers do not result in chronic exposure of employees
even to low levels of radiation. A large number
of these examinations have been performed in the
past, and no indication of any detectable biologic
change was noted. Employers may wish to offer their
employees periodic eye examinations or other medical
examinations as a health benefit; however, there
does not appear to be any valid reason to rcquire such
examinations as part of a medical surveillance program.
E2.1.3 T€rmination Medical Exarninations,
The primary purpose of termination examinations is
for the legal protection of the employer against
unwarranted claims for damage that might occur after
an employee leaves a particular job. The decision on
whether to offer or require such examinations is left
to individual employers.
E2.2 Examination Proaocols
E2.2.1 Ocular History. The past eye history and
family history are reviewed. Any current complaints
concemed with the eyes arc noted. Inquiry should be
made into the general health status with a special
emphasis upon systemic diseases which might produce
ocular prcblems in regard to thc performance
cited in Section 6.1. The current reftaction prescription
and the date of the most recent examination
should be recorded.
Certain medical conditions may cause the laser
worker to be at an increased risk for chronic exposure.
Use of photosensitizing medications, such as
phenothiazines and psoralens, lower the threshold for
biological effects in the skin, comea, lens and retina
of experimental animals exposed to ultraviolet and
near ultraviolet radiation. Aphakic individuals would
be subject to additional retinal exposure from neaf
ultraviolet and ultraviolet radiation. Unless chronic
viewing of these wavelengths is required, there
should be no reason to deny employment to these
individuals.
E2.2.2 Visual Acuity, Visual acuity for far and
near vision should bc measured with som{: standardized
and reproducible method. Refraction conections
should be made if required for both distant and near
test targets. If refractive corrections are not sufficient
to change acuity to 20/20 (6/6) for distance, and
Jaegsr l+ for ncu, a more extensive examination is
indicated as defined in 6.3.
84
E2.2.3 Macular Function. An Amsler grid or
similar pattem is used to test macular function for
distortions and scotomas. The test should be administered
in a fashion to minimize malingering and false
negatives. If any distortions or missing portions of
the grid pattem are present, the test is not nomal.
E2.2.4 Contrast Sensitivity Contrast (or glare)
sensitivity should be documented by the Arden
sine-wave pattems or similar acuity tests which
include low contrast images.
E2.2.5 Examination of the Ocular Fundus with
an Ophthalnioscope This portion of the examination
is to be administered to individuals whose ocular
function in any of Sections E.2.2.1 through E.2.2.'l is
not normal. The points to be covered are: the prcsence
or absence of opacities in the media; the sharpness
of outline of the optic disc; the color of the optic
disc; the depth of the physiological cup, if present;
the ratio of the siz€ of the retinal veins to that of the
retinal aneries; the presence or absence of a well'
defined macula and the presence or absence of a
foveal rcflex; and any retinal pathology that can be
seen with an ophthalmoscope (hyper-Pigmentation,
depigmentation, retinal degeneration, exudate, as well
as any induced pathology associated with changes in
macular funcdon). Even small deviations from normal
should be described and carefully localized.
E2.2.6 Skin Examination. Not rcquired for preplacement
examinations of laser workers; however,
suggested for employees with history of photosensi
tivily or working with ultraviolet lasers. Any previous
dermatological abnormalities and family history
are reviewed. Any cunenl complaints concemed
with the skin are noted as well as the history of medication
usage, particularly concentrating on those
drugs which are potentially photosensitizing.
Further examination should be based on the type of
laser radiation, above the appropriate MPE levels,
present in the individual's work environment.
E2.2.7 Other Examinations, Funher examinations
should be done as deemed necessary by the examiner.
83.0 Medical Referral Following Suspected or
Known Laser Injury
Any employce with a suspected cye injury should be
referred to an ophthalmotogist. Employees with skin

,l
,O
injuries should be seen by a physician-
E4.0 Records and Record R€tention
Complete and accumte records of all medical examinations
(including specific test rcsults) should be
maintained for all personnel included in the medical
surveillance program. Records should be retained for
at least 30 yean.
E5.0 Access To Records
The results of medical surveillance examinations
should be discussed
wirh the employee.
All non-personally identifiable records of the medical
surveillance examinations acquired in Section E.4 of
these guidelines should be made available on written
rcquest to authorized physicians and medical consultants
for epidemiological purposes. The record of
individuals will, as is usual, be furnished upon
request to the private physician.
E6,0 EpidemiologicStudies
Past use of lasers has generally been stringently controlled.
Actual exposure of laser workers has been
minimal or even nonexistent. It is not surprising that
acute accidental injury has been rare and that the few
repons of repeated eye examinations have not noted
any chronic eye changes. For these reasons, the
examination requirements of this standard are
minimal. However, animal experiments with both
laser and narrow-band radiation indicate the potential
for chronic damage from both subacute and chronic
exposure to radiation at certain wavelengths. Lens
opacities have been produced by radiation in the
0.?95 to 0.45 pm range and are also theorerically possible
from 0.75 to 1.4 um.
Photochemical retinitis appears to be inducible by
exposure to 0,35 to 0.5 pm radiation. Iflaser systems
are developed that require chronic exposure of laser
workers to even low levels of radiation at these
wavelengths, it is recommended that such workers be
included in the long-term epidemiologic studies and
have periodic examinations of the appropriate eye
suucures.
r O ;;::rui'ff J:iff l}",'ffi ;:T,"itffi ;,:';
are suggested.
E7.0 References
APPENDIX
Friedman, A. L The ophthatmic screening of laser
workers. Ann Occup Hyg. 2l: 277 -279: 1978.
Hathaway, J. 4., Stem, N., Soles, E. M., teighton, E.
Ocular medical surveillance on microwave and laser
workers. J. Occup Med. 19:683-688; 1977.
Hathaway, J. A. The Needs for Medical Surveillance
of Laser and Microwave Workers. Current Concepts
in Ergophthalmology. Societas Ergophthalmologica
Intemationalis. Sweden: 139-l60; 1978.
Wolbarsht, M. L., and Landen, M. B. Testing visual
capabilities for medical surveillance or to ensure job
fitness. J. Occup Med. 77:897-901: 1985.
Appendix F
Special Considerations
The operation of lasers and laser systems, like any
industrial or technological process, involves various
possible related hazards. The following special considerations
apply to such associated hazards of laser
or laser system operation.
Fl. Compressed Gases
The potential oxygen deficiency hazard associated
with lhe use of asphyxiant compressed gases should
'|ol be overlooked,
The following standards, regulations, and guidelines
should be observed while using compressed gases:
American National Standard Method of Marking
Portable Compressed Cas Containers to ldentify the
Material Contained. ANSUCGA C-4-1978.
American National Standard Compressed Gas
Cylinder Valve Outlet and Inlet
ANSVCCA V-r -19??.
Connections,
Handbook of Compressed Cases. Compressed Gas
Association, 1966. Available from Compressed Gas
Association, 500 Fifth Avenue, New York, New
York 10036.
Peninent regulations of the U.S. Department of Transportation
(for example, Title 49, Code of Federal
Regulations, Parts 170-179).

APPENDIX
F2. Cryogenic Liquids
Cryogenic liquids should tre stored and handled in
accordance with the instructions listed in the Handbook
of Compressed Gascs (sec Fl ).
F3. Ventilation
Local exhaust of general dilution ventilation systems
must be provided to keep thc lcvels of toxic fumes,
vapors, mists, dusts and gases, in occupied areas
below the permissible exposure limits as set forth in
Title 29, Code of Federal Regulations, Pan
1910.1000, Subpart Z, Air Contaminants. Oxygen
levels should be maintained at least 19 58" by
volume. Additional ventilation requirements and
design information may be obtained from the cunent
issue of lndustrial ventilation, published by the
American Conference of Covemmental Industrial
Hygienists ( 14th ed, 1976, Cincinnati, Ohio).
F4, Ionizing Radiation
The source, quality and intensity of X-rays emanattng
from laser power supplies and components therein
should be investigated and controlled in accordance
with the provisions listed in Anrerican National Standard
"General Safety Standard for Installations
Using Non-Medical X-Ray and Sealed Gamma-Ray
Sources, Energies up to t0 MeV," ANSI/l'lBS Handbook
I14, and any applicable federal, state, or local
codes and regulations.
F5. Toxic Materials
F5.l Personnel exposures to toxic or carcinogenic
materials must be maintained within permissible
exposure limits by ventilation. enclosure, isolation.
substitution, shielding, of other aPpropriate engineering
controls, ot by proper utilization of personnel
protective equipment. Federal health standards exposure
criteria should be followed. ln absence of
Federal health standards, exposure criterid containcd
in NIOSH Criteria Documents and ACCIH Threshold
Limit Values should be followed.
F5.2 Polychlorinated biphenyls (PCBs) may also
become a potential problem when working in areas
where transformers and capacitors are used. Contact
with any transformer or capacitor oil which may
It6
contain PcB-bearing askarel should be prcvented as
much as possible through use of Viton or similar type
rubber personal-protective equipment. Respiratory
protective gear should be used as waranted. PCBS
and PCB equipment must be handled' used, stored'
labeled and disposed of in accordance with EPA
Regulations (Title 40, Code of Federal Regulations,
Pan 761).
F5.3 Special optical materials used for far infrared
windows and lenses have been the source of
dangerou$ levels of airbome contaminants. For
example, calcium telluride and zinc telluride will
bum in the presence of oxygen when beam iradiance
limits are exceeded. Cadmium oxide is suspected of
carcinogenic potential in man; therefor€ atmospheric
concenFation of the fume should b€ maintained at oa
trelow the 0.05 mg/m3 ceiling level established by
ACGIH. Tellurium and tellurium hexafluoride arc
also quite toxic and therefore exPosure to these
materials should be controlled.
F5.4 The use of dimethylsulfoxide (DMSO) as a
solvent for cyanine dyes in dye lasen shoutd be discontinued
if possible. DMSO aids in the transPort of
dyes into the skin. If another solvent cannot be
found, low permeability gloves (e.g. Neoprene or
nitrile) should be worn by personnel any time a spill
occurs or in situations where contact with the solvent
may occur. The dyes themselves are often very toxic
and in some instances may even be carcinogenic.
F6. References
F6.1 Associat€d Hazards
American National Standard National Electrical
Code. ANSI NFPA 70-1984 (or latest revision
thereo0.
Certilied Equipment List as of October l, 1987.
DHHS (NIOSH) Publication No 88-107. Superintendent
of Docunrents, U.S. Govemement Printing
Office, Washinglon, D.C. 20402, October 1987.
Hygienic Guide Series Detroit: American lndustrial
Hygiene Association.
lndustrial Ventilntion - A Manual of Recommended
Practice. l4th ed. Cincinnati: American Conference
of covemmcnlal Industrial Hygienists; 1972 (or
latest revision thereoo.
Key, M.M.. et al., Occupational Diseases - A Guide
to Their Recognition. DHEW (NIOSH) Publication
No. 77-181. Superintendent of Documents, U.S

jJ Gotemment Printing Qffice, Washington, D.C.
, 20402. Revised Edirion June 1977.
Koller, L. R. Ultravioler Radiation. 2nd ed. New
York: John Wiley & Sons; 1965.
Patty, F. A., ed. Industrial Hygiene and Toxicology.
2nd ed. New York: Interscience publishers: l97g_
1982: v.lIA, IIB, IIC and III.
Proctor, N., Hughes, J. and Fischman, M. eds.
Chemical Hazards of the Workplace. J.p. Lippincott
Co., Philadelphia, Pa. Znd revision, 1988.
Registry of Toxic Effects of Chemicat Substances,
Vol l-5 and subsequent updates. Sweei, D.V. ed.
DHHS (NIOSH) Publicarion No. 87-t t4, Superinten_
dent of Dccuments, U.S. Govemment printing Office,
Washington, D.C. 20402. April 1987.
Sliney, D. H., Freasier, B. C. The evaluation of ootical
radiarion hazards. Applied Optics. l2(t); l-?2;
1973 lan.
Sliney, D. H., Wolbarsht,
M. L. Safety with Lasers
and Other Optical Sources. New York: plenum pub_
lishing Co; 1985.
APPENDIX
Middleton, W. E. K. Vision through rhe Atmosphere.
Toronto: University ofToronto Press; 1968_
Sliney, D. H. Eyaluating health hazards from military
lasers. Joumal of the American Medical Association.
214(6): 1047 -1054; 1970 Dec.
Tatarski, V. I. Wave Propagation in a Turbulent
Medium. New York: McGraw-Hill Company; 1960.
Appendix G
,o ;J,
it,t"H::.# ii:11'Jl,:l'f"T#Hi,i,"#;
tl
TLVs - Threshold Limit Values and Bioloeical
Exposure lndices for 1988-1989. American Coiference
of Govemmental Industrial Hygienists; 1988 (or
current edition).
Title 29, Code of Federal Regulations, pan 1910,
Safety and Health Standards. Occupational Safety
and Health Administration, U.S. Dept. of Labor.
F6.2 OpticalPropagation
Buck, A. L. Effects of ahosphere on laser beam
propagation. Applied Optics. 6(4): 703-708; 1967
Apr.
Burch, D. E., Cryvnak, D. A., Pauy, R. R. Absorption
of infrared radiarion by COr and H2O -. absorption
by CO2 between 8000 and t0,000 cm-r. Joumal
of the Oprical Sociery of America. 58(3): 335_341:
1968 Mar.
Deitz, P. H. Twelve eye safety nomographs. Applied
Optics. lt(2): 371-375; 1969 Feb.
Hogg. D. C. Millimetcr wave communicalion
lH?:Jhe atmosPhere' science' r5e(3810): 3e-46:
Biological Effects on the Eye end Skin
Gl. Minimal Biological Effects of Laser Radiation
on the Eye
Gl.l General. Among different laboratories
some differences in standardization and calibration
probabiy exist. This has introduced a certain spread
among the data. Tlte majority of the work in aniving
at the MPES in Section 8 of the standard has been
concemed with how to compare the data and which
data should be given more consideration. Where
regression lines were available, they indicate that a
factor of 10 below the 50% damage level gave a
negligible probability of damage. Whenever possible
these regression lines formed the basis for the level
selecred for any pafticular MPE. Where the data
indicated a steeper regression line, a factor less than
10 was used.
Gl.2 Corneal Damage
Gl,2.l Infrared (Spectral Region 1.4 to 1000
pm). Excessive infrared exposure causes a loss of
lranspar€ncy or produces a surface irregularity in the
cornea. The MPE is well below the erergy or power
required to produce a minimal lesion, For the purposes
of this standard, a minimal comeal lesion is a
small white area involving only the epithelium and
whose surface is not elevated or swollen. lt appears
within l0 minutes after the exposure. Very linle or
no staining results from fluorescein application. A
minimal lesion will heal within 48 hours without visible
scarring. These observations are based on experiments
with COz lasers; extrapolation to wavelengths
other than 10.6 Jrm must be made with care.
Damage results from the heating of the comea by
absorprion of the incidenr energy by tears and tissue
watcr in the comea, The absorption is diffuse, and
87

APPENDIX
simple heat flow models aPpear to be valid The
identity of the sensitive material or protein in the cornea
is not knowo. Although the critical temperature
threshold is not known, it doe$ not appear to be much
above normal body temperatute, and there are indications
that it is a function of exposure time.
G1.2.2 Ultraviolet (Spectral Region 0'2 to 0.4
pm). Excessive utraviolet exposure produces photophobia
accompanied by redness, tearing, conjunctival
discharge, surface exfoliation, and stromal haze The
MPE is well below the energy required to produce
(within 24 houn following exposure) any of the
changes named.
Damage to the epithelium by absorption of ultraviolet
light probably results from photochemical denaturation
of proteins or othet molecules in the cells Some
of the most important molecules are the deoxyribonucleic
acids (DNA) and ribonucleic acids (RNA). The
absorption is probably by selective sensitive portions
of single cells. The action of the ultraviolet radiation
is photochemical rather than thermal, since the temperature
rise calculated for experimental exposure is
negligible.
Gl.3 Retinal Damage (Spectral Region 0.4 to
1.4 pm), The MPE is well below the exposure
required to produce a minimal (or threshold) lesion'
For the purposes of this standard, a minimal retinal
lesion is the smallest ophthalmoscopically visible
change in the retina. This change is a small white
patch (apparently coagulation) which occurs within
24 hours of the time of exposure. At threshold the
lesion is probably the result of local heating of the
retina subsequent to absorption of the light and its
conversion to heat by the melanin granules in the pigment
epithelium.
Extended exposure lasting several minutes for a rctinal
image that is very small is difficult to accomplish,
except by slabilized image optics. Thus there exist
no experimental data for long exposures and small
spot sizes. However, accidental retinal exposures
which combine long periods of time and small spot
sizes are very unlikely.
Gl.4 Other Ocular Damage. There are two transition
zones between comeal hazard and retinal
hazard spectral regions, These are located at the
wavelength bands separating the ultraviolet and visible
regions and separating near infrared and infrared.
The exact wavelengths are not known. In these
regions there may be both comeal and retinal damage.
Also. damage to intermediate structures, such as
the lens and iris. can occur.
88
Gl.S References. The most important references
are cited in this section. They cover the major Portion
of the data used in deriving this Standard.
Several of the teferences are review articles; their
bibliographies should be used as a source of additional
references.
Adams. D. O.; Beatrice, E. S.; Bedell' R. B. Retinal
ulrastructural alterations produced by extremely low
levels of coherent radiation. Science. 177(4043):58-
60; 197? July 7.
Bresnick, G. H., Frisch, G. D" Powell' J. O"
Landers. M. B.. Holst, G. E., and Dallas, A. C. Ocu'
lar effects of argon laser radiation - Part I: Retinal
damage threshold studies' InvestigativeOphthalmology.
9(l t):901-910; 1970 Nov'
Clark, A. M. Ocular hazards from lasers and other
optical sources. Critical Reviews in Environmental
Control. (3): 307-339; 1970 Nov.
Cogan, D. C. L€sions ofthe eye from radiant energy.
Joumal of the American Medical Association.
142(3): 145-l5l; 1950 Mar.
Desvignes, P., Amar, L., Bruma, M., Velge, M. Sur la
generaiion d'ondes ulFasonores et formation de
bulles das le vitre d'un oeil humain par inadiation
d'impulsion laser. Comptes Rendus Hebdomadaircs
des Seances de I'Academie des Sciences. 259:
1588-1591: 1964.
Dunsky, 1.. Lappin, P. Evaluation of retinal threshold
for cw radiation. Vision Research. ll(7): 733-73E;
l97l July.
Gibbons, W. D. Threshold Damage Evaluation of
Long-Term Exposures to Argon Laser Radiatiolr,
U.S. Depanment of the Air Force Report SAM-TR-
'14-29,
1914 Aug. Available from National Technical
Information Service, Springfeld, Va. 22161.
Ham, W. T., Jr., Clarke, A. M., Geeraets, W' J.'
Cleary, S. F., Mueller, H. A., Williams' R. C. The
eye problem in laser safety. Archives of Environ'
mentat Health. 20(2): 156-160; 1975 Feb.
Ham, W. T.. Jr., Geeraets, W. J., Mueller' H. A"
Williams, R. C., Clarke, A. M., Cleary, S. F. Retinal
bum thresholds for the helium-neon laser in the
rhesus monkey. Archives of Ophthalmology.
84(12): 797-808; 1970 Dec.
Ham. W. T., Jr., Mueller, H' A., Sliney' D. H. Retinal
sdnsitivity to damage from shon wavelength light.
Nature. 260(5547): 153-155; 1976 Mar I I'

Ham, W. T., Jr., Williams, R. C., Mueller, H. A.,
cl Guerry, D., Clarke, A. M., Geeraets, W. J. Effects of
laser radiation on the mammalian eye. Transactions
of the New York Academy of Sciences, ser 2.28:
517-526; 1966 Feb.
Hansen, W. P., Fine, S. Melanin granule models for
pulsed laser ipduced retinal injury. Applied Optics
7(l): 155-159: 1968 Jan.
Hayes, J. R., Wolbarsht, M. L. Thermal model for
retinal damage induced by pulsed lasers. Aerospace
Medicine. 39(5): 474480: 1968 May.
Kuwabara, T- Retinal recovery from exposure to
light. American Joumal of Ophthalmology. 70(2):
187-198; 1970 Aug.
Laser Health Hazards Conrol. U.S. Department of
the Air Force Manual AFM-l6l-32, 1973 Apr 20.
Available from Nadonal Technical Information Service,
Springfield, Va. 22161.
Peabody, R. R., Zweng, H. C., Rose, H. W.,
Peppers, N. A., Vassiliadis, A. Threshold damage
from COz lasers. Archives of Ophthalmology.
82(?): 105-107; 1969 July.
rO Hn:;.- ^',Jffii:f;.^ "'-'::'l',Ifi
:
Zweng, H. C. Corneal damage threshotds for CO2
laser radiation. Applied Optics. 8(2):37't-381; 1969
Feb.
Pitts, D. G., Bruce, W. R., Tredici, T. J. A. Comparative
Study of the Effecrs of Ultraviolet Radiarion on
the Eye. U.S. Air Force School of Aerospace Medicine
Repon SAM-TR-70-28. Aerospace Medical
Division (AFSC), Brooks Air Force Base, 1970.
Available from National Technical Information Service,
Springfield, Va, 22 t6t.
Sliney, D. H. The development of laser safety criteria.
In: M. L. Wolbarsht, ed. Laser Applications in
Medicine and Biology. New York: Plenum Press;
l97l: v. l, chapter 7, pp 163-238.
Vassiliadis, A. Ocular damage from laser radiation.
In: M. L. Wolbarsht, ed. Laser Applications in Medicine
and Biology. New York: Plenum Press; 1977: v.
l, chapter 6, pp 125-162.
Voss, J. J. A theory of rctinal bums. Bulletin of
Mathematical Biophysics. 24: I l5-128; 1962.
, r r,*** ih":#'T'li,I*"ixll il; :g;
1970 Sepr.
APPENDIX
Wolbarsht, M. L., Sliney, D. H. The formulation of
protection standards for lasers. In: M. L. Wolbarsht,
ed. Laser Applications in Medicine and Biology.
New York: Plenum Pressl 1974l' v. 2, chapter 10, pp
309-360.
G2. Biological Effects of Lsser Radiation on the
Skin
G2,l General. The large $kin surface makes this
body tissue readily available to accidental and
repeated exposures to laser radiation. The biological
significance of irradiation of the skin by lasers operating
in the visible and infrared regions is considerably
less than exposurc of the eye, as skin damage is usually
reparable or revenible. Effecs may vary from a
mild rcddening (erythema) to blisters and charring.
Depigmentation, ulceration, and scaning of the skin,
and damage to underlying organs, may occur from
exlremely high-powered laser radiation.
Latcnl and cumulative effects of laser radiation are
not known at this time. The possibility of such
effects occurring, however, should not be ignored in
planning for personnel safety in laser installations.
Little or no data is available describing the reaction of
skin exposed to laser radiation in the 0.2 to 0.4 pm
spectral region, but chronic exposure to ultraviolet
wavelengths in this runge can have a carcinogenic
action on skin as well as eliciting an erythematous
response.
On the basis of studies with noncoherent ulffaviolet
radiation, exposure to wavelengths in the 0.25 to
0.32pm spectral region is most injurious to skin.
Exposure to rhe shoner (0.2 to 0.25 pm) and longer
(0.32 to 0.4 pm) ultraviolet wavelengths is considercd
less harmful to normal human skin. The
shoner wavelengths are absorbed in the outer dead
layer of the epidermis (stratum comeum), and exposure
to the longer wavelengths has a pigmentdarkening
eflbct. However, the sensitivity of skin to
the longer wavelengths may be increased by known
or inadvertent usage of photosensitizers.
G2.2 References
Buchanan, A. R., Heim, H. G., Stilson, D. W.
Biomedical Effects of Exposure lo Electromagnetic
Radiation - Pan I: Ultr-dviolet. Air Development
Center Technical Report 60-376, AD 244 786, 1960
May. Available from National Technical Information
Service, Springfield ,Y a.2216l .
89

o
APPENDIX
Goldman, L., Rockwell, R. 1., Jr. l.asers in Medicine.
New York: Gordon and Breach Science Publishers;
197 t.
Lane, R. J., Linsker, R., Wynne, J. J., Torres, A., and
Geronemus, R. G. Ultraviotet - laser ablation of
skin. Archives of Dermatology. I2l:(609-617) May,
1985.
[,aor, Y., Simpson, C., Klein, 8., Fine, S. Pathology
of intemal viscera following laser radiation. American
Joumal of the Medical Sciences. 257(4): 242-
252; 1969 Apr.
Panish. J. A. and Anderson. R. R.. Considentions of
selectivity in laser therapy. ln Amdt, K. A., Noe, J.
M. and Rosen, S. (eds.): Cutaneous Laser Therapy -
Principles and Methods. New York: John Wiley and
Sonsl 1983.
Pan, W. H. Skin f€sion Threshold Values for Laser
Radiation as Compared with Safety Standards. U.S.
Army Medical Research Inboratory Repon 813, AD
688 871, 1969- Available from National Technical
lnformation Service, Springfield, Va. 22161.
Rockwell, R. J., Jr, Goldman, L. Research on Human
Skin Laser Damage Threshold. Final Repon, University
of Cincinnati, Conract F41609-72-C-0007,
School of Aerospace Medicine, Brooks Air Force
Base. Texas.
Sliney, D. H., wolbarsht, M. L. Safety with Lasen
and Other Optical Sources. New York: Plenum Puhlishing
Company; 1980.
Threshold Limit Values and Biological Exposure
Indices for 1988-1989. Cincinnati: American Conference
of Governmental Industrial Hygienists.
Urbach, F., ed. The Biological Effects of Ulhaviolet
Radiation (with Emphasis on the Skin). Proceedings
of the First Intemational Conference, 1966. New
York: Pergamon Press; 1969.
Appendix H
M€asuremenls
Hl. Radiometric Measurements
lt is important to note that certain aypes of radiometrically
calibrated instruments can exhibit substantial
90
enors when used to measurc cohercnt radiation.
These enors are often associated with interfercnce
phenomena (constructive and deslructive) or with
spatial inhomogeneities, and instrument readings can
change greatly with small changes in angle of
incidence, wavelength, or distribution of radiation
over the surface. It is, therefore, imponant to select
instruments that minimize such effects or are
designed specifically for use with lasers. As an
example, current National Institute of Science and
Technology (NIST) laser power and energy standards
are based on calorimehic rather than radiometric
techniques (see A Reference Calorimeter for Laser
Energy Measurements, by E. D. West and others
which is listed as a reference in H4)
H2, Radiant Exposure Profiles and Radiant
Dxposure Estimates for Pulsed Lssers
Several rypes of photosensitive or thermally sensitive
papers or emulsions may be used as aids in the determination
of laser beam radiant exposure and for
estimating beam profiles of high-energy lasers.
H3. Beam Div€rgence
Determination of the divergence of the laser beam
may be required when evalualing exposures at fal
distances from the laser. It is recommended that
beam divergence be detemined by using either maximum
beam irradiance or radiant exposurc at two different
distances from the laser and calculating with
Ec B4 in 83.2.3. (See also 3.4.2.)
H4. References
H4.1 General
Case, W. E. Documentation of the NBS C, K, Laser
Calibration Systems. NBSIR 82-1676, September
1982.
Day, C. w., Hamilton, C. A., Pyatt, K. W. Spectral
reference detector for the visible to 12 micrometer
region; convenient, spectrally flat. Applied Optics.
l5(7): I865- 1868, July 1976.
Sliney, D. H., Wolbarsht, M. L. Safety with Lasers
and Other Opticai Sources. New York: Plenum Publishinq
Co: 1980.

Sanders, A. A., Rasmussen, A. L. A System for
Measuring Energy and Peak Power of l.ow-Level
1.0@ Micrometer Laser Pulses. National Bureau of
Standards Technical Note 1058; Washington, D.C.
U.S. Govemment Printing Office. 1982.
Danielson, B, L, Measur€ment Procedures for the
Optical Beam Splitter Attenuation Device A-1.
NBSIR 77-858. Washington, D.C. U.S. Govemment
Printing Office. 1977.
Wolfe, W. L., Zissis, G. J. The Infrared Handbook.
Washington, D.C. U.S. Govemment Printing Office.
1978.
Hamilton, C. A., Day, G. W. A Pyroelectric Power
Meter for the Measurement of Low Level Radiation.
National Bureau of Standards Technical Note 665.
Washington, D.C. U.S. Govemment Printing Office.
197 5.
West, E. D., Case, W. E., Rasmussen, A.L., Schmidt,
L. B. A reference calorimeter for laser energy measurements.
Joumal of Research of the National
Bureau of Standards, Sect. A (Physics and Chemistry).
764( l): l3-26; 1972 Jan-Feb.
Franzen, D. L., Schmidt, L. B. Absolute reference
calorimeter for measuring high power laser pulses.
Applied Optics. l 5(12):3 1 1 5 -J 122; 1976 Dec.
APPENDIX
H4.2 Commercially Available Instrumentation.
Periodically updated listings of commercially available
laser measuring insfiuments ere included in the
following publications;
Electro-Optical Master Catalog. Available from Milton
S. Kiyer Publications, htc,, 222 west Adams
Street, Chicago, Itl. 60606.
Instrumeltation for Environmental Monitoring -
Radiation. Available from Environmental Instrument
Group, Lawrcnce Bertley Laboratory, University of
Califomia, Berkeley, Calif. 94720.
Laser Focus Buyers'Guide. Available from Penwell
Publications, Advanced Technology Group, 119
Russell St. Littleton, MA 01640.
The Optical Industry and Systems Purchasing Dircctory.
Available from Laurin Publishing Company,
Berkshire Common, P.O. Box 1146, Pittsfield, MA
o1202.
Lasen and Applications, Technical Handbook and
Industry Directory, 23868 Hawthome BIvd. Torrance.
CA 90505.
9l

Table l0
Control Measures for the Four Laser Classes
Controls Classification I za 2 3a 3b
ProtectiYe Housing (4.3. 1) X X X X X X
E
without Protective Housing (4.3. l.l )
lnterlocks on Protective Housing (4.3.2)
Service Access Panel (4.3.3)
LSO shall establish Altemate Controls
A A X X x
V v v V v X
N Key Swilch l\4aster (4.3.4) X
G
t
N
E
Viewing Ponals (4.3.5.l)
Collecting Optics (4.3.5.2)
Totally Open Beam Path (4.3.6.1)
Limited Open Beam Path (4.3.6.2)
tr
D
tr
tr
o
D
X
X
o
tr
x
x
E Remote Interlock Connector (4.3.7) X
R Beam Stop or Attenuator (4.3.E)
X
I Activation Waming Systems (4.3.9)
X
N Emission Delay (4.3.9.1)
G Class 3b Laser Controlled Area (4.3.10. | )
X
Class 4 l,aser Controlled Area (4.3.10.2)
X
Laser Outdoor Controls (4.3.1 I )
Temporary Laser Controlled Area* (4.3.12) v v
X X
Remote Firing & Monitoring (4.3.13)
Labels (4.3.14) x X X X X
Area Posting (4.3.15) X X
Administrative & Procedural Controls (4.4) X X x X X
A Standard Operating Procedures (4.4.1) X
M Output Emission Limitations (4.4.2) LSO f Etermination
N R Education and Training (4.4.3) X X x
i
ri
oa
U
c Authorized Personnel (4.4.4) X X
D Alignment Procedures (4.4.5) x X X x
T R Eye Prctection (4.4.6)
I
L Spe€tator Control (4.4.?) X
Service Personnel (4.4.8) v X X
Laser Demonstration (4.5. 1 ) x X X x
Laser Fiber Optics (4.5.2) X x X. x
LEGEND X - Shatl, . - Should, - No requirement, V-Shall if Embedded Cla-ss 3botClass4'
c - Shat t if MpE is exceeded. A - Shall if embedded Class 3a, Class 3b, Class 4, * During Service Only
X

lo
]o
}r LIA'.8G5M
Laser Institute of America
The Laser Institute of America in 1984 assumed the secretariats of the two major laser
safety standards committees which impact upon both user and manufacturers. These
committees are the American National Standards Institute (ANSI) Committee 2-136
on Safe Use of Las€rs, and the International Electrolechnical Commission (ICE)
Technical Committee TC-76 on Lasers. The first committee plays a leadership role in
establishing occupational exposure limits and standard safety practices in lhis country.
The second committee serves the same role worldwide, and most national organizations
look toward this committee for guidance.
The Laser Institute of America is a nonprofit professional society devoted entirely to
the advancement and promotion of laser technology and applications. The Instilute conducts
continuing education courses, seminars and technical symposia nationwide, and
offers a variety of educational materials and publications. Journal of Laser Applications
is the official society magazine published four times a year for members.
LASER SAFETY PUBLICATIONS-from Laser Institute of America
Standards
o Safe Use of lasers, ANSI ZI36.I-1986
. Sale Use of Optical Fiber Communication Systems utilizing Inser Diode and
LED Sources, ANSI Z,136.2-1988
o Safe Use of Lasers in Health Care Facilities, ANSI 2136.3-1988
General
. Inser SaIetJ Cuide (39p)
c Guide Jor Selection of Laser Eye Protection (l8p)
o Safety Reference Notebook (1 I9p)
o lnser Safet!: Bio-Effects, Hazards & Classifications (96p)
. Laser Safety Short Courses Tefi (3-ring, 380p)
t Safery SlidelAudio Educational Package (35mm135 min.)
o Laser SaIeO Video.Training Package
. C onfere nc e P roc e edings
SEND FOR FREE CATALOG OR CALL (407) 380 - 1553 for derailed information,
(Se@nd Ptinring enh Ctua@ rd Cteificarionc)
Laser Institute of Amenca
12424 Research Parkway, Suite 130
Orlando, FL 32826
(407) 380 - | 553
FAX (407) 380 - 5588