li-190sa quantum sensor li-190sa quantum sensor

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®

Table of Contents
LI-190SA Quantum Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . .1
LI-191SA Line Quantum Sensor . . . . . . . . . . . . . . . . . . . . . . .2
Underwater PAR Measurement . . . . . . . . . . . . . . . . . . . . . . . .3
LI-192SA Underwater Quantum Sensor . . . . . . . . . . . . . . .3
LI-193SA Spherical Quantum Sensor . . . . . . . . . . . . . . . . .3
LI-200SA Pyranometer Sensor . . . . . . . . . . . . . . . . . . . . . . . . .5
LI-210SA Photometric Sensor . . . . . . . . . . . . . . . . . . . . . . . . .6
Sensor Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
LI-250 Light Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
LI-1400 DataLogger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
LI-1401 Agro Meteorological System . . . . . . . . . . . . . . . . . . . .14
LI-1405 Basic Weather Station . . . . . . . . . . . . . . . . . . . . . . . . .15
Optical Radiation Calibrator . . . . . . . . . . . . . . . . . . . . . . . . . . .17
LI-1800 Portable Spectroradiometer . . . . . . . . . . . . . . . . . . . . .18
Radiation Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
“Trust in the LORD with all your heart; and do not lean on your own understanding. In all your ways acknowledge Him, and He
will make your path straight.”Proverbs 3:5,6
The LI-COR Board of Directors would like to take this opportunity to return thanks to God for His merciful providence in allowing
LI-COR to develop and commercialize products, through the collective effort of dedicated employees, that enable the examination of
the wonders of His works.

LI-190SA QUANTUM SENSOR
LI-190SA QUANTUM SENSOR
MEASURE PHOTOSYNTHETICALLY
ACTIVE RADIATION
During photosynthesis, plants use energy in the region of the
electromagnetic spectrum from 400-700 nm (3,9). The radiation
in this range, referred to as
Photosynthetically Active Radiation
(PAR), can be measured in energy units
(watts m -2 ) or as Photosynthetic Photon
Flux Density (PPFD), which has units of
quanta (photons) per unit time per unit
surface area. The units most commonly
used are micromoles of quanta per second
per square meter (µmol s -1 m -2 ).
LI-190SA Quantum Sensor
Plant scientists, horticulturists, ecologists,
and other environmental scientists
use the LI-190SA Quantum Sensor to accurately measure this
variable.
Accurate measurements are obtained under all natural and artificial
lighting conditions because of the computer-tailored spectral
response of the LI-190SA. Colored glass filters are used to tailor
the silicon photodiode response to the desired quantum
response (Figure 1). An interference filter provides a sharp cutoff
at 700 nm, which is critical for measurements under vegetation
where the ratio of infrared to visible light may be high. A
small response in the infrared region can cause an appreciable
measurement error. This sensor, developed from earlier work
(1), was pioneered by LI-COR and has become the standard for
PPFD measurement in most photosynthesis-related studies.
The LI-190SA is also used in oceanography, limnology, and
marine science as a reference sensor for comparison to underwater
PAR measured by the LI-192SA Underwater Quantum
Sensor.
* Units currently used are moles, einsteins, photons and quanta (2, 4, 5).
1 µmol s -1 m -2 ≡ 1 µE s -1 m -2 ≡ 6.02 × 10 17 photons s -1 m -2 = 6.02 × 10 17
quanta s -1 m -2 .
PERCENT RELATIVE RESPONSE
100
80
60
40
20
0
ULTRAVIOLET
LI-COR
QUANTUM SENSOR
VIOLET
BLUE
IDEAL QUANTUM RESPONSE
GREEN
400 500 600 700
YELLOW
WAVELENGTH – NANOMETERS
RED
INFRARED
LI-190SA SPECIFICATIONS
Absolute Calibration: ± 5% traceable to the National Institute of
Standards and Technology (NIST).
Sensitivity: Typical 5µA per 1000 µmol s -1 m -2 .
Linearity: Maximum deviation of 1% up to
10,000 µmol s -1 m -2 .
Stability: Typically < ± 2% change over a
1 year period.
Response Time: 10 µs.
Tilt: No error induced from orientation.
Operating Temperature: -40 to 65°C.
Relative Humidity: 0 to 100%.
Temperature Dependence: 0.15% per °C
maximum.
Cosine Correction: Cosine corrected up to
80° angle of incidence.
Azimuth: < ± 1% error over 360° at 45°
elevation.
Detector: High stability silicon photovoltaic detector (blue enhanced).
Sensor Housing: Weatherproof anodized aluminum case with acrylic
diffuser and stainless steel hardware.
Size: 2.38 cm Dia. × 2.54 cm H (0.94” × 1.0”).
Weight: 28 g (1 oz).
Cable Length: 3.0 m (10 ft).
ORDERING INFORMATION
The LI-190SA Quantum Sensor cable terminates with a BNC connector
that connects directly to the LI-250 Light Meter or LI-1400 DataLogger.
The 2290 Millivolt Adapter should be ordered if the LI-190SA will be
used with a strip chart recorder or datalogger that measures millivolts.
The 2290 uses a 604 Ohm precision resistor to convert the LI-190SA
output from microamps to millivolts. The Quantum Sensor can also be
ordered with bare leads (without the connector) and is designated
LI-190SZ. Both are available with 50 foot cables, LI-190SA-50 or
LI-190SZ-50. The 2003S Mounting and Leveling Fixture is recommended
for each sensor unless other provisions for mounting are made.
Other accessories are described on the Accessory Page.
LI-190SA Quantum Sensor
LI-190SZ Quantum Sensor
LI-190SA-50 Quantum Sensor
LI-190SZ-50 Quantum Sensor
2290 Millivolt Adapter
2003S Mounting and Leveling Fixture
2222SB-50 Extension Cable
Figure 1. Typical spectral response of LI-COR Quantum Sensors
vs. Wavelength and the Ideal Quantum Response (equal response
2222SB-100 Extension Cable
to all photons in the 400-700 nm waveband). 1

LI-191SA LINE QUANTUM SENSOR
U.S. Patent 4,264,211.
quantum response. Second, the single quantum sensor is much
easier to keep in calibration than multiple (up to 80) individual
gallium arsenide detectors.
LI-191SA SPECIFICATIONS
Absolute Calibration: ± 10% traceable to NIST. The LI-191SA is
calibrated via transfer calibration from a LI-COR reference
Quantum Sensor.
The LI-191SA Line Quantum Sensor spatially
averages PPFD over its one meter length.
MEASURE PHOTOSYNTHETICALLY ACTIVE
RADIATION IN PLANT CANOPIES
During photosynthesis, plants use energy in the region of the
electromagnetic spectrum from 400-700 nm (1, 2). The radiation
in this range, referred to as Photosynthetically Active
Radiation (PAR), can be measured in energy units (watts m -2 ) or
as Photosynthetic Photon Flux Density (PPFD) which has units
of quanta (photons) per unit time per unit surface area. The
scaled units most commonly used are micromoles of quanta per
second per square meter (µmol s -1 m -2 ).
Measuring PAR within a plant canopy can be very difficult
because of the non-uniformity of the light field. When PAR is
measured with a small diameter quantum sensor such as the
LI-190SA Quantum Sensor, intensity can vary 10-fold between
sunflecks and shadows, requiring a large number of readings to
get an accurate average. The LI-191SA Line quantum Sensor
reduces the number of individual readings required because it
effectively averages PPFD over its one meter length. One
person can quickly make plant canopy PPFD measurements in
many plots in a short period of time.
Rather than using multiple detectors linearly arranged over its
one meter length, the LI-191SA uses a 1 meter long quartz rod
under a diffuser to conduct light to a single high quality quantum
sensor whose response is shown in Figure 1. There are two
advantages of this design. First, the sensor has a very good
quantum response unlike sensors using inexpensive gallium
arsenide detectors with only an approximation of the ideal
Sensitivity: Typically 7 µA per 1000 µmol s -1 m -2 .
Linearity: Maximum deviation of 1% up to 10,000 µmol s -1 m -2 .
Stability: < ± 2% change over a 1 year period.
Response Time: 10 µs.
Temperature Dependence: ± 0.15% per °C maximum.
Cosine Correction: Acrylic diffuser.
Azimuth: < ± 2% error over 360° at 45° elevation.
Sensitivity Variation over Length: ± 7% maximum using a 1” wide
beam from an incandescent light source.
Sensing Area: 1 meter L × 12.7 mm W (39.4” × 0.50”).
Detector: High stability silicon photovoltaic detector (blue enhanced).
Sensor Housing: Weatherproof anodized aluminum case with acrylic
diffuser and stainless steel hardware.
Size: 116 L × 2.54 W × 2.54 cm D (45.5” × 1.0” × 1.0”).
Weight: 1.8 kg (4.0 lbs.).
Cable Length: 3.1 m (10.0 ft.).
ORDERING INFORMATION
The LI-191SA Line Quantum Sensor comes with a bubble level,
detachable 10 ft. cable and hardsided carrying case. The cable is
terminated with a BNC connector and can be directly connected
to a readout device such as the LI-250 Light Meter, LI-1400
DataLogger or to the 2290 Millivolt Adapter for connecting to
readout devices requiring a millivolt signal. Other accessories
are described on the Accessory Page.
LI-191SA Quantum Sensor
2290 Millivolt Adapter
2222SB-50 Extension Cable
2222SB-100 Extension Cable
2

UNDERWATER PAR MEASUREMENT
LI-192SA UNDERWATER QUANTUM SENSOR
Underwater or Atmospheric PPFD Measurement
Underwater or atmospheric Photosynthetic Photon Flux
Density (PPFD) can be accurately measured using the
LI-192SA Underwater Quantum Sensor. The LI-192SA is
cosine corrected and features corrosion resistant, rugged
construction for use in freshwater or saltwater and pressures
up to 800 psi (5500 kPa, 560 meters depth).
LI-192SA SPECIFICATIONS
Absolute Calibration: ± 5% in air traceable to NIST.
Sensitivity: Typically 4 µA per 1000 µmol s -1 m -2 in water.
Linearity: Maximum deviation of 1% up to 10,000
µmol s -1 m -2 .
Stability: < ± 2% change over a 1 year period.
Response Time: 10 µs.
Temperature Dependence: ± 0.15% per °C maximum.
Cosine Correction: Optimized for underwater and
atmospheric use.
Azimuth: < ± 1% error over 360° at 45° elevation.
Detector: High stability silicon photovoltaic detector (blue
enhanced).
Sensor Housing: Corrosion resistant metal with acrylic diffuser
for both saltwater and freshwater applications. Waterproof to
withstand 800 psi (5500 kPa, 560 meters).
Size: 3.18 cm Dia. × 4.62 cm H (1.25” × 1.81”).
Weight: 227 g (8 oz.).
Mounting: Three 6-32 holes are tapped into the base for use
with the 2009S Lowering Frame or other mounting devices.
Cable: Requires 2222UWB Underwater Cable.
UNDERWATER PAR MEASUREMENT
Accurate measurement of Photosynthetically
Active Radiation (PAR, 400-700 nm) in
aquatic environments is accomplished using
either the LI-192SA Underwater Quantum
Sensor or the LI-193SA Spherical Quantum
Sensor. Limnologists, oceanographers and
biologists conducting aquatic productivity
studies and vertical profiling have used these
sensors extensively.
For extremely turbid conditions, radiation
levels with resolution to 0.01 µmol s -1 m -2
can be measured with the LI-192SA or
LI-193SA quantum sensors and the
LI-1400 DataLogger.
Both the LI-192SA and the LI-193SA use
computer-tailored filter glass to achieve the
desired quantum response. Calibration is
traceable to NIST.
LI-193SA SPHERICAL QUANTUM SENSOR
Underwater PAR From All Directions
0.1 1.0 10 100 1000
The LI-193SA Underwater Spherical Quantum Sensor gives an
added dimension to underwater PAR measurements as it measures
photon flux from all directions. This measurement is
referred to as Photosynthetic Photon Flux Fluence Rate (PPFFR)
or Quantum Scalar Irradiance. This is important, for example,
when studying phytoplankton which utilize radiation from all
directions for photosynthesis.
The LI-193SA features a high sensitivity optical design and
compact, rugged construction (3400 kPa, 350 meters depth).
Depth (m)
1
2
3
4
5
6
7
8
9
10
11
-1 -2
µmol s m
Down Welling
Up Welling
LI-193SA SPECIFICATIONS
Absolute Calibration: ± 5% in air traceable to NIST.
Sensitivity: Typically 7 µA per 1000 µmol s -1 m -2 in water.
Linearity: Maximum deviation of 1% up to 10,000
µmol s -1 m -2 .
Stability: < ± 2% change over a 1 year period.
Response Time: 10 µS.
Temperature Dependence: ± 0.15% per °C maximum.
Angular Response: < ± 4% error up to ± 90° from normal axis
(see Figure 3).
Azimuth: < ± 3% error over 360° at 90° from normal axis.
Detector: High stability silicon photovoltaic detector (blue
enhanced).
Clockwise: LI-190SA Quantum Sensor, LI-192SA Underwater Quantum
Sensor, LI-193SA Spherical Quantum Sensor
3

UNDERWATER PAR MEASUREMENT (CONT).
Sensor Housing: Corrosion resistant metal for both saltwater
and freshwater applications with an injection molded,
impact resistant, acrylic diffuser. Units have been tested
to 500 psi (3400 kPa, 350 meters) with no failures.
Size
Globe: 6.1 cm Dia. (2.4”).
Housing: 3.18 cm Dia. (1.25”).
Overall Height: 10.7 cm (4.2”).
Weight: 142 g (0.31 lbs.).
Mounting: Three 6-32 mounting holes are tapped into
the base for use with the 2009S Lowering Frame or
other mounting devices.
Cable: Requires 2222UWB Underwater Cable.
2009S LOWERING FRAME LOWERING
Ø= 270°
Ø= 0°
8
6
4
2
Ø= 180°
Figure 3.
Typical Angular Response of the
LI-193SA Spherical
Quantum Sensor. The
low response on the
bottom of the sensor
Ø= 90° is due to light blockage
by the detector
housing. The error
due to this low response
is not significant in most
cases because of the small
portion of upwelling radiation
compared to the total radiation.
The 2009S Lowering Frame provides for the placement of two
underwater cosine sensors, one each for downwelling or
upwelling radiation (shown below), or a single LI-193SA
Spherical Quantum Sensor. The 2009S provides stability for
proper orientation of the sensor(s), minimizes shading effects,
and features a lower mounting ring for stabilizing weight attachment
if necessary.
Construction: Anodized aluminum.
Size: 51.4 L (20.3”) × 35.6 cm W (14.0”).
Weight: 327 g (0.72 lbs.).
2222UWB UNDERWATER CABLE
This 2-wire shielded cable is used with underwater sensors and
has a waterproof connector on the sensor end. The other end of
the cable is fitted with a BNC connector for attaching the cable
directly to the readout instrument for type “SA” sensors (also
attaches to the calconnector of “SB” type sensors). Standard
cable lengths are 3, 10, 30, 50, 75, and 100 meters. Custom
lengths over 100 meters can also be ordered.
Underwater Sensors require 2222UWB Underwater Cable
ORDERING INFORMATION
LOWERING
The Underwater Sensors can be purchased with several accessories.
Please see Accessory Page for more details.
2009S Lowering Frame
LI-192SA Underwater Quantum Sensor
LI-193SA Spherical Quantum Sensor
2009S Lowering Frame
2291 Millivolt Adapter (1210 ohm)
2222UWB-3 Underwater Cable, 3 meters
2222UWB-10 Underwater Cable, 10 meters
2222UWB-30 Underwater Cable, 30 meters
2222UWB-50 Underwater Cable, 50 meters
2222UWB-75 Underwater Cable, 75 meters
2222UWB-100 Underwater Cable, 100 meters
100L Lubricant
4

®
ENVIRONMENTAL DIVISION
LI-200SA PYRANOMETER SENSOR
TOTAL SOLAR RADIATION
The LI-200SA Pyranometer is designed for field measurement of
global solar radiation in agricultural, meteorological, and solar
energy studies. In clear unobstructed daylight conditions, the
LI-COR pyranometer compares favorably with first class thermopile
type pyranometers (5, 11), but is priced at a fraction of
the cost.
Patterned after the work of Kerr, Thurtell and Tanner (7), the
LI-200SA features a silicon photovoltaic detector mounted in
a fully cosine-corrected miniature head. Current output, which
is directly proportional to solar radiation, is calibrated against an
Eppley Precision Spectral Pyranometer (PSP) under natural daylight
conditions in units of watts per square meter (W m -2 ).
Under most conditions of natural daylight, the error is

®
LI-210SA PHOTOMETRIC SENSOR
MEASURES ILLUMINANCE AS RELATED TO
THE CIE STANDARD OBSERVER CURVE
Sensor Housing: Weatherproof anodized aluminum case with
acrylic diffuser and stainless steel hardware.
Size: 2.38 Dia. × 2.54 cm H (0.94” × 1.0”).
Weight: 28 g (1 oz.).
Cable Length: 10 ft. standard.
LI-210SA Photometric Sensor
PHOTOMETRIC SENSORS
Photometry refers to the measurement of visible radiation (light) with a sensor
having a spectral responsivity curve equal to the average human eye.
This curve is known as the CIE Standard Observer Curve (photopic curve).
Photometric sensors are used to measure lighting conditions where the eye
is the primary receiver, such as illumination of work areas, interior lighting,
television screens, etc. Although photometric measurements have been
used in the past in plant science, PPFD and irradiance are the preferred
measurements.
The LI-210SA Photometric Sensor utilizes a filtered silicon photodiode
to provide a spectral response that matches the CIE
curve within ± 5% with most light sources. This photodiode and
filter combination is placed within a fully cosine-corrected sensor
head to provide the proper response to radiation at various
angles of incidence.
100
80
60
PHOTOMETRIC
SENSOR
CIE PHOTOPIC CURVE
40
Some of the applications for the LI-210SA Photometric Sensor
include interior and industrial lighting, outdoor illuminance,
passive solar energy, architecture and lighting models, illumination
engineering, and biological sciences that require illuminance
measurements. The LI-210SA is a research grade photometric
sensor that is very reasonably priced.
20
0
ULTRAVIOLET
VIOLET
BLUE
GREEN
YELLOW
RED
400 500 600 700
WAVELENGTH – NANOMETERS
INFRARED
LI-210SA SPECIFICATION
Absolute Calibration: ± 5% traceable to NIST.
Sensitivity: Typically 30 µA per 100 klux.
Linearity: Maximum deviation of 1% up to 100 klux.
Stability: < ± 2% change over a 1 year period.
Response Time: 10 µS.
Temperature Dependence: ± 0.15% per °C maximum.
Cosine Correction: Cosine corrected up to 80° angle
of incidence.
Azimuth: < ± 1% error over 360° at 45° elevation.
Tilt: No error induced from orientation.
Operating Temperature: -20 to 65 °C.
Relative Humidity: 0 to 100%.
Detector: High stability silicon photovoltaic
detector (blue enhanced).
ORDERING INFORMATION
The LI-210SA Photometric Sensor cable terminates with a BNC
connector that connects directly to the LI-250 Light Meter or
LI-1400 DataLogger. The 2290 Millivolt Adapter should be
ordered if the LI-210SA will be used with a strip chart recorder
or datalogger that measures millivolts. The 2290 uses a 604
Ohm precision resistor to convert the LI-210SA output from
microamps to millivolts. The Photometric Sensor can also be
ordered with bare leads (without the connector) and is designated
LI-210SZ. The 2003S Mounting and Leveling Fixture is recommended
for each sensor unless other provisions for mounting
are made. Other accessories are described on the Accessory
Page.
LI-210SA Photometric Sensor (with BNC connector)
LI-210SZ Quantum Sensor (with bare leads)
2003S Mounting and Leveling Fixture
2222SB-50 Extension Cable (50 ft.)
2222SB-100 Extension Cable (100 ft.)
2290 Millivolt Adapter
6

SENSOR ACCESSORIES
ACCESSORIES FOR
TERRESTRIAL SENSORS
2003S Mounting and Leveling Fixture
The 2003S is for use with all LI-COR terrestrial type sensors
(2.38 cm Dia.). The base is anodized aluminum with stainless
steel leveling screws and a weatherproof spirit level.
Size: 7.6 cm Dia. (3.0”).
Weight: 95 g (0.21 lbs).
Type SZ Sensors
Type SZ sensors have the same specifications as the type SA
sensors except that they are terminated with bare wires for connection
to the terminal blocks for the LI-1400 DataLogger or
other current measuring devices. These sensors can be converted
to millivolt output by connecting a resistor across the leads
and measuring the voltage across the resistor.
ACCESSORIES FOR
UNDERWATER SENSORS
2222UWB Underwater Cable
This 2-wire shielded cable is used with underwater sensors and
has a waterproof connector on the sensor end. The other end of
the cable is fitted with a BNC connector for attaching the cable
directly to the readout instrument for type “SA” sensors (also
attaches to the calconnector of “SB” type sensors). Standard
cable lengths are 3, 10, 30, 50, 75 and 100 meters. Custom
lengths over 100 meters can also be ordered.
2222SB Extension Cable
This cable is for use with LI-COR terrestrial type sensors.
Standard length is 15.2 m (50 ft) or 30.4 m (100 ft). Custom
lengths up to 304 m (1000 ft) may be ordered. Cable lengths up
to 1000 feet can be used with LI-COR readout instruments. For
mV applications, consult LI-COR.
2009S Lowering Frame
The 2009S Lowering Frame provides for the placement of two
underwater cosine sensors, one each for downwelling or
upwelling radiation (shown below), or a single LI-193SA
Spherical Quantum Sensor. The 2009S provides stability for
proper orientation of the sensor(s), minimizes shading effects,
and features a lower mounting ring for stabilizing weight
attachment if necessary.
Millivolt Adapters
Millivolt adapters are used only for connecting sensors to a
user’s datalogger or stripchart recorder, not the LI-1400 or other
LI-COR readout devices.
Construction: Anodized
aluminum.
Size: 51.4 L (20.3”) x 35.6 cm
W (14.0”).
Weight: 327 g (0.72 lbs.).
2290 Millivolt Adapter
For LI-190SA Quantum Sensor, LI-191SA Line Quantum
Sensor, or LI-210SA Photometric Sensor (604 Ohm resistance).
2220 Millivolt Adapter
For LI-200SA Pyranometer Sensor (147 Ohm resistance).
2291 Millivolt Adapter
For LI-192SA Underwater Quantum Sensor or LI-193SA
Spherical Quantum Sensor (1210 Ohm resistance).
Underwater Sensors
Require 2222UWB Underwater Cable. The 2009S Lowering
Frame is an accessory.
100L Lubricant
Provides lubrication between the sensor and the underwater
cable.
7

LI-250 LIGHT METER
Direct Digital Readout: Instantaneous sensor output
or 15 second averages can be shown on the LI-250's
display. Measurement units for any LI-COR sensor
(µmol, lux, klux, or W m -2 ) are also displayed.
High Quality Circuitry: The high quality amplifier in
the LI-250 provides excellent long term stability and
automatic zeroing. This high gain amplifier gives very
low input impedance to sensors, resulting in excellent
linearity. Typical accuracy is 0.4% of reading at 25 °C.
Automatic Range Selection: The LI-250 simplifies
operation by automatically selecting the range with
the best accuracy and resolution for a given sensor
input signal. The wide dynamic range allows measurements
in a wide variety of light environments.
Hold Key: Pressing the HOLD key lets you retain
the current reading on the display. Pressing the
HOLD key again returns the LI-250 to measurement
mode where the display is continuously updated.
Average Key: 15 second averages can be collected
and then held on the display by pressing the AVG key.
Hand-held, Battery Operated: The LI-250's low
power consumption gives you over 150 hours of
operation from a single 9-volt transistor battery. To
conserve battery life, the meter automatically shuts
off after 20 minutes of inactivity.
Sensor Calibration: Calibration multipliers for LI-COR sensors can be
entered by simply pressing the CAL key, setting the display units (UNITS
key), and then changing the sensor calibration multiplier with the up and
down arrow keys. Two sensor multipliers can be held in memory to aid in
switching between sensors.
APPLICATIONS
Like all LI-COR instruments, the LI-250 is designed for applications
demanding performance, reliability and ruggedness.
The LI-250 provides direct digital readout of LI-COR radiation
sensors.
Photosynthetically Active Radiation (PAR)
The LI-190SA Quantum Sensor is used by plant scientists, horticulturists,
and other environmental scientists to measure
Photosynthetic Photon Flux Density (PPFD - the preferred
measurement of PAR) in natural sunlight, under plant canopies,
and in growth chambers and greenhouses.
The LI-190SA is also used in oceanography, limnology and
marine sciences as a reference sensor for comparison to underwater
PPFD measured by the LI-192SA Underwater Quantum
Sensor. The LI-250 can hold calibration multipliers in memory
for both a surface and underwater sensor.
Solar Irradiance
Solar irradiance measurements for meteorological, hydrological
and environmental research can be made using the LI-200SA
Pyranometer Sensor. The LI-200SA measures global solar
radiation (sun plus sky) and provides a typical accuracy of
±5% under unobstructed daylight conditions.
SENSOR COMPATIBILITY
Type "SA" sensors (e.g. LI-190SA) are recommended for use
with the LI-250. Older type "SB" sensors (e.g. LI-190SB) can
also be used by removing the calibration connector. Other types
of older LI-COR sensors can be made compatible by adding a
BNC connector to the cable.
Illuminance
For lighting studies or architectural modeling, the LI-250 and
LI-210SA Photometric Sensor provide a direct readout of illuminance
in lux. The LI-210SA measures visible radiation and has
a spectral response curve equal to that for the average human
eye. This curve is known as the CIE Standard Observer
Curve and is matched by the LI-210SA to within 5% under most
light sources.
LI-250 Light Meter with LI-210SA Photometric Sensor
and 2003S Mounting and Leveling Fixture.
8

ACCESSORIES
250-01 Carrying Case: The 250-01 has a tough nylon exterior
and is padded to protect the LI-250 during transport. Internal
compartments provide storage for the LI-250 and several sensors.
For field use, the 250-01 also lets you hang the meter on
your belt.
Size: 20 L × 9.5 W × 9 cm D.
Operating Conditions: 0 to 55 °C, 0 to 95% RH
(non-condensing).
Storage Conditions: -55 to 60 °C, 0 to 95% RH
(non-condensing).
Size: 14 cm L × 7.7 cm W × 3.8 cm D (5.5" × 3" × 1.5").
Weight: 0.26 kg (0.57 lbs).
Warranty: 1 year parts and labor.
LI-250 RANGE AND RESOLUTION
Sensor Range Resolution
250-01 Carrying Case.
LI-250 SPECIFICATIONS
Accuracy:
25 ˚C: Typically ± 0.4% of reading ± 3 counts
on the least significant digit displayed
(all ranges).
0 - 55 ˚C: Typically ± 0.6% of reading ± 3 counts
on the least significant digit displayed
(all ranges).
Range Selection: Autoranging (3 ranges).
Linearity: ± 0.05%.
Sensors: Any LI-COR type "SA" or type "SB” sensor with
BNC connector; Quantum, Pyranometer, or Photometric. Older
LI-COR radiation sensors, or those without any connector must
have a BNC connector installed. Contact LI-COR.
Sensor Calibration: Each sensor is supplied with a calibration
multiplier. Calibration multipliers for two sensors can be stored
in memory. Calibration multipliers are entered from the keypad.
Signal Averaging: Sensor output can be collected and displayed
as a 15 second average (approximately 60 readings). Averages
are retained on the display in HOLD mode.
Display: 4 1/2 digit LCD display. Updated every 0.5 seconds
in Instantaneous mode.
Keypad: Sealed, 5-key tactile response keypad.
Battery Life: 150 hours typical with continuous operation.
Power Requirement: One 9V Eveready Alkaline #522 or
equivalent (LI-COR part number 216).
Low Battery Detection: Low battery indicator displayed with
approximately 20 hours battery life remaining.
Quantum 199 µmol s -1 m -2 0.01 µmol s -1 m -2
1999 0.1
19999 1
Radiometric 19 W m -2 0.001 W m -2
199 0.01
1999 0.1
Photometric 1999 lux 0.1 lux
19999 lux 1
199 klux 0.01 klux
ORDERING INFORMATION
LI-250 Light Meter
Battery included. Order sensors separately.
Options
250-01 Carrying Case
216 Replacement Battery. 9 volt transistor type.
Requires 1 for replacement.
Sensors
LI-190SA Quantum Sensor
LI-200SA Pyranometer Sensor
LI-210SA Photometric Sensor
LI-191SA Line Quantum Sensor
2003S Mounting and Leveling Fixture
2222SB Extension Cable (50 ft.)
2222SB-100 Extension Cable (100 ft.)
Underwater Sensors
LI-192SA Underwater Quantum Sensor
LI-193SA Spherical Quantum Sensor
2222UWB Underwater Cable. Standard lengths
range from 3 to 100 meters. Custom lengths are
available.
2009S Lowering Frame
9

LI-1400 DATALOGGER
High accuracy with LI-COR light sensors. Three
external light sensor connectors for fast setup.
Two additional current channels, four voltage
channels, one pulse counting channel and several
regulated and unregulated voltage supplies.
96K Bytes RAM for data storage.
Ergonomic, light weight for hand-held operation as
a meter with instantaneous or averaged readout.
Nine math channels for direct readout of saturation
vapor pressure, dew point temperature, vertical light
attenuation coefficients (underwater), and more.
Two line LCD display shows sensor instantaneous
or logged sensor outputs, stored data,
battery voltage and more.
Autoranging electronics with low power consumption.
Easy to use internal software with setup macro
libraries to simplify sensor configuration.
RS-232C data output to PC-compatible or Macintosh
computers in "spreadsheet-ready" format.
Alphanumeric keypad speeds entry of remarks for
data identification.
SIMPLIFIED DATA LOGGING
Operating the LI-1400 is easy. All functions are selectable from
short lists using cursor keys. Commonly used functions like
printing and memory management are assigned to a function list
on a dedicated key for quick access. Other important functions
like instrument setup and data display are also assigned to dedicated
keys.
FAST SETUP
Channel setup is simplified by the use of log routines
that eliminate entering repetitive information. The
LI-1400's log routines allow you to enter the logging
period, start/stop times and other information in one
place, and then apply that log routine to as many
channels as required.
Each channel can be individually configured to
collect data for logging periods as short as 1 second
or as long as 24 hours. Sampling intervals within
each logging period are selectable from 1 second to one hour.
For each logging period, data can be integrated or averaged.
Alternatively, an instantaneous point reading can be taken at
the end of each period. The maximum and minimum readings
within the logging period and the time of their occurrence can
also be stored.
MATH FUNCTIONS
Channel setup includes choosing from a list of math functions
that can be applied to sensor inputs. In addition to sensor input
scaling or linearization, several powerful calculations can be performed
using math functions:
Math Operators (+, –, ×, ÷): Used to combine one input with
another through channel addition, subtraction, etc. For example,
math operators can determine the ratio of two similar sensors in
different environmental conditions, like an LI-190SA Quantum
Sensor at the water's surface and an LI-192SA Quantum Sensor
underwater.
Steinhart-Hart Function: Calculates temperature from thermistor
type temperature sensors such as
LI-COR air and soil temperature sensors.
Saturation Vapor Pressure: Calculated
when temperature is input from an air temperature
sensor.
Dew Point Temperature: Calculates the
dew point temperature using signals from
the 1400-104 Relative Humidity and Air
Temperature Sensor (or equivalent).
Natural Log: Multiplies a constant by the
natural log of a channel input. When used
in conjunction with math operators, this function can be used to
calculate the vertical light attenuation coefficient between two
underwater quantum sensors submerged at different depths.
Polynomial: A fifth order polynomial is provided for sensor
linearization.
Math Libraries: Five math libraries are available to store values
for any of the above math functions. For example, if the same
linearization polynomial is to be used for several sensor inputs,
storing the polynomial in one of the math libraries eliminates
re-entering the polynomial for every sensor.
10

MATH CHANNELS
The logging and calculation capabilities of the LI-1400 are
extended by nine math channels. Math channels let you perform
additional logging or math routines using any other current,
voltage or math channel. For example, if you are
logging total daily solar radiation from an LI-200SA
Pyranometer sensor connected to current channel #1,
you can also log hourly integrations or averages from
the same sensor by adding the channel #1 input to a
math channel and then setting the log routine on the
math channel for hourly integrations. Any of the
math operators or math functions described above can
be used in the math channels as well.
CIRCUITRY
The LI-1400 uses an autoranging, trans-impedance,
chopper stabilized amplifier for high resolution (8
picoamp), high accuracy measurements of LI-COR radiation
sensors and other sensors with a current output. The high gain
amplifier and unique circuit topology gives an extremely low
input impedance (< 0.03 ohm) to current sensors, resulting in
excellent linearity. Measurement accuracy is enhanced by performing
an auto zero and span before every reading (or once per
minute with 1 second sampling rate) using a high precision, low
drift reference. A precision sigma-delta analog-to-digital converter
allows high speed, low noise measurements to be made.
Highly accurate, single-ended voltage measurements are
achieved using a precision instrumentation amplifier. Voltage
output transducers with low or high output impedance are accurately
measured because of very high amplifier input impedance.
CURRENT CHANNELS
The LI-1400 has unrivaled resolution for LI-COR radiation sensors.
Current resolution down to 8 picoamps is available
through three sealed BNC connectors and two additional channels
on the 1400-301 Terminal Block.
The three BNC current channels are designed for type "SA"
radiation sensors like LI-COR's LI-190SA Quantum Sensor,
LI-200SA Pyranometer Sensor or LI-210SA Photometric Sensor.
LI-COR Type "SZ" radiation sensors, with bare wire leads, are
recommended for use with the terminal block.
For other sensors, the LI-1400 can measure current up to ± 250
microamps with very high resolution.
VOLTAGE CHANNELS
Four single-ended voltage channels (± 2.5 VDC) provide high
input impedance for measuring a wide range of sensors,
including LI-COR temperature sensors and humidity sensors.
Voltage measurements require the 1400-301 Terminal Block.
PULSE COUNTING
The LI-1400 has one pulse counting channel for logging total
rainfall from LI-COR's 1400-106 Tipping Bucket Rain Gauge
(or equivalent). The counter channel can be accessed through
the 1400-301 Terminal Block.
ENVIRONMENTAL OPERATION
The LI-1400's rugged, splash resistant case
protects it from exposure to the environment.
Operating temperatures are from
-25 to 55 °C. For operation at remote sites,
the 1400-201 Vented Instrument Enclosure
is recommended to protect sensor connections
from rain water and to shade the
LI-1400 from direct sunlight.
The LI-1400 is powered by four "AA"
batteries which provide over 60 hours of
hand-held, instantaneous operation as a
meter. For remote logging applications, the
1400-402 external "D" cell battery pack
provides over a year of data logging operation from six batteries.
To ensure continuous operation, a low battery warning is
displayed when the batteries are depleted; a lithium back-up
battery protects the memory while changing batteries.
While logging data, the LI-1400 conserves battery life by
operating fully powered only when it must sample a given
channel. After sampling channels and storing data (if necessary),
the LI-1400 automatically returns to a state of low power
consumption.
DATA STORAGE
The LI-1400 has 96K bytes RAM for data storage. The storage
capacity is dependent on the software configuration.
DATA OUTPUT
Windows 95 ® communication software is included for:
• Rapid binary data transfer
• ASCII data transfer
• Datalogger configuration changes
from the computer.
Stored data can also be transferred to PC-compatible or
Macintosh computers using any terminal program. The LI-1400
data is formatted for easy import into widely used spreadsheet
and database software.
Data can be automatically output via the RS-232 port after
every logging period. When using short logging periods, this
feature allows data capture by a computer with large storage
capacity.
HAND-HELD OPERATION
As an autoranging meter, the LI-1400 provides direct readout for
up to three LI-COR radiation sensors without requiring a
terminal input block.
The output of a given sensor can be viewed on the LCD display
11

or stored in memory by simply pressing
the ENTER key on the keypad (data for
all operative channels are stored, along
with the time at which the data were
logged).
Radiation measurements in water or under changing cloud cover
often require an averaged reading of sensor output to obtain the
best results. The LI-1400 can display a continuous running
average for each sensor. The length of the average is user selectable
for each channel. Instantaneous or averaged values for any
sensor can also be displayed while the LI-1400 is logging data.
1400-102 Air Temperature Sensor: Same as 1400-101 except
cable length is 2 ft. for mounting in 1400-201 Vented Instrument
Enclosure.
1400-104 Relative Humidity and Air Temperature Sensor
(Vaisala): 9 ft. cable. Can be mounted in 1400-201 Vented
Instrument Enclosure.
1400-106 Tipping Bucket Rain Gauge: Calibrated in millimeters.
Tipping bucket mechanism activates a sealed reed switch
that produces a contact closure for each 1 mm of rainfall. 50
foot cable.
ORDERING INFORMATION
LI-1400 DataLogger: Includes 4 "AA" batteries and Windows
95 ® communication software. Sensors not included.
1400-301 Standard Terminal Block: Allows connection to two
additional current channels, 4 voltage channels, 1 pulse counting
channel, two unregulated voltage supplies, and two regulated +5
volt DC supplies for LI-COR temperature sensor and other
sensors requiring a constant voltage input.
1400-401 AC Adapter: Requires 120 VAC, 60 Hz. Used for
applications where continuous operation is required.
1400-402 External Alkaline Battery Pack: Holds 6 "D" cell
batteries for remote logging applications. The 1400-402 has
provisions for mounting in the 1400-201 Vented Instrument
Enclosure.
1400-320 Storage Case: Foam-lined
plastic case for LI-1400, sensors, and
accessories.
1400-201 Vented Instrument Enclosure:
Wooden enclosure to limit exposure of
1400-301
LI-1400 and sensor connections.
Dimensions: 19L × 19W × 56 cm H (7.5”
× 7.5” × 22”). Weight: 4.8 kg (10.5 lb).
Includes one 1400-310 Mounting Bracket.
1400-310 Mounting Bracket: For mounting the LI-1400 in
third-party instrument enclosures, or any other vertical or
inclined surface.
SENSORS
Quantum Sensors: LI-190SA Quantum Sensor, LI-190SZ
Quantum Sensor, LI-191SA Line Quantum Sensor, LI-192SA
Underwater Quantum Sensor, LI-193SA Spherical Quantum
Sensor.
Pyranometer Sensors: LI-200SA, LI-200SZ.
Photometric Sensors: LI-210SA, LI-210SZ.
1400-103 Soil Temperature Sensor: 20 foot cable.
Accuracy: ± 0.5 °C.
1400-101 Air Temperature Sensor: 20 foot cable.
Accuracy: ± 0.5 °C.
1400-104 Relative Humidity/Temperature Sensor,
1400-101 Air Temperature Sensor, and 1400-103 Soil
Temperature Sensor (left to right).
DATA OUTPUT ACCESSORIES
1400-550 RS-232C Cable: For connection to PC-compatible
computers with a 9-pin RS-232C communication port (DTE-to-
DTE).
SPECIFICATIONS
Current Inputs: Five channels; three through external sealed
BNC connectors, and two through the 1400-301 Standard
Terminal Block.
Voltage Inputs: Four high impedance (>500M ohm) singleended
channels accessed through the 1400-301 Terminal Block.
Pulse Counting Input: One pulse counting channel. Switch
closure for tipping bucket rain gauge (1 Hz maximum).
Math Channels: 9 math channels. Math channels combine
results of two channels with addition, subtraction, multiplication
and division operators. Other math channel functions include
fifth order polynomial, Steinhart-Hart function for thermistors,
natural log, saturation vapor pressure, and dew point. Five math
libraries are available to store commonly used functions.
Analog-to-Digital Converter:
Resolution: 16 bit (1 part in 65,536).
Scanning Speed: 10 channels per second.
Voltage Accuracy: < 0.1% of full scale reading
(25 °C). ± 0.15% (0 to 55 °C).
Current Accuracy: ± 0.2% of full scale reading
(25 °C). ± 0.4% (0 to 55 °C).
12

Temperature Coefficient: ± 0.01% of reading per °C.
Linearity: 0.07%.
Frequency Rejection: >90 dB at 50 or 60 Hz (software
selectable).
Input Noise (25 °C)
Typical
Maximum
Voltage ± 76 µV ± 152 µV
Current ± 7.6 picoamps ± 30.4 picoamps
Voltage Range (Channels V1-V4):
Voltage Range
Resolution:
± 2.5 volts 76 microvolts
Current Range Selection:
Autoranging.
Current Ranges
Resolution
1 ± 250 nanoamps 7.6 picoamps
2 ± 2.5 microamps 76 picoamps
3 ± 25 microamps 760 picoamps
4 ± 250 microamps 7.6 nanoamps
Typical Resolution with LI-COR radiation sensors (Range 1)
LI-190SA .0015 µmole sec -1 m -2
LI-200SA .0001 watts m -2
LI-210SA .025 lux
Current Channel Input Impedance: Typically < 0.03 ohm for
ranges 1, 2, or 3; < 0.3 ohm for range 4.
Voltage Channel Input Impedance: >500M ohm on voltage
channels V1 through V4. 100K ohm for current channels I4 and
I5, when configured for voltage input.
D.C. Voltage Excitation: Two regulated: + 5.0 V ± 0.2% at 3
mA; Two unregulated: 9.5V ±10% or higher at 6mA. With external
14V input, unregulated output is ≈13.4V.
Logging Periods: Seconds: 1, 5, 15, 30. Minutes: 1, 5, 15, 30.
Hours: 1, 3, 6, 12, 24.
Sampling Interval: Seconds: 1, 5, 15, 30. Minutes: 1, 5, 15,
30, 60.
Short Term Averaging: Selectable at 1, 5, 15, or 30 seconds.
While averaging, the oldest point is dropped when the newest
point is added. Averaged readings reduce instrument noise by
approximately the square root of the number of samples.
Keyboard: Sealed, 24 key tactile response keypad.
Display: Two line, 16 character alphanumeric LCD. Updated
once per second. Temperature compensated readability from -15
to 55 °C.
Real Time Clock: Year, month, day, hour, minute, seconds.
Accuracy: ± 3 minutes per month (25 °C).
Internal Memory: 96K bytes available for data storage.
Program Memory: Stored in Flash memory for easy upgrades
via the RS-232 port.
Communications: RS-232C, hardwired Data Terminal
Equipment (DTE) through 9-pin port. Baud rates are software
selectable at 300,1200, 2400, 4800 and 9600. Communication is
bi-directional.
Battery Requirements: Four Alkaline "AA" batteries in sealed
battery compartment.
Back-up Battery: Internal lithium battery maintains memory
up to seven years.
Battery Voltage: Automatic low battery instrument shut-off.
Remaining power after shut-off maintains data stored in memory.
Low battery warning displayed before automatic shut-off.
Power management software also shuts off the instrument after
15 minutes of inactivity.
Battery Capacity with "AA" Batteries: 60 hours continuous
operation.
External DC Power: 7 - 16 VDC.
Case: ABS plastic case for splash resistant operation and protection
from wind blown dust. Equivalent to an IP54 level.
Operating Conditions: -25 to 55 °C; 0 to 95% RH, non-condensing.
Storage Conditions: -30 to 60 °C; 0 to 95% RH,
non-condensing.
Size: 22L × 13W × 4.3 cm D (8.6 × 5.1 × 1.7”). 9.3 cm (3.7")
width of the lower case allows easy hand-held operation.
Weight: 0.7 kg (1.5 lb).
13

LI-1401 AGRO-METEOROLOGICAL STATION
The LI-1401 Agro-Meteorological Station is a complete meteorological
data logging system designed for simple operation
and easy setup.
The LI-1401 includes the LI-1400, a 10-channel data logger,
and all sensors needed to collect total daily solar irradiance,
precipitation, air temperature, soil temperature, relative
humidity, wind speed, and wind direction.
A dedicated software configuration provides for simple setup.
Simply choose the desired sampling and logging periods, and
you're ready to collect data. Data stored in memory can be
viewed on the LCD display, or output to a computer. Data
can be offloaded in the field without interrupting the logging
process.
The heavy duty, self-guying tripod makes site selection simple,
and allows easy transport to multiple locations for crop
modeling, plant growth studies, soil characterization, irrigation
scheduling, and crop management applications.
INCLUDES THE FOLLOWING:
LI-1400 DataLogger
1400-301 Terminal Block
LI-200SA Pyranometer
1400-103 Soil Temperature Sensor
1400-104 Air Temperature/Relative Humidity Sensor
(Vaisala)
1400-105 Wind Direction/Speed Sensors (RM Young)
1400-106 Tipping Bucket Raingauge
1400-204 Tripod (self guying design)
1400-205 Mounting Bar
1400-202 Gill Radiation Shield
1400-203 Sealed Instrument Enclosure
1400-402 External Alkaline Battery Pack
1400-550 RS-232 Communications Cable (9-pin to 9-pin)
14

LI-1405 BASIC WEATHER STATION
The LI-1405 Basic Weather Station is an economical weather
station designed to measure the basic meteorological parameters
required for agricultural research. The vented instrument
enclosure mounts easily to a pole or post and not only
provides protection for the data logger and battery pack, but
serves as a mounting platform for the pyranometer and the air
temperature sensor. Data are easily downloaded in spreadsheet-ready
format to a PC with the included software.
An economical alternative to the LI-1401, the LI-1405 Basic
Weather Station contains the same 10-channel datalogger
(LI-1400), with sensors to measure solar radiation, air and soil
temperature, and rainfall. These measurements provide a basic
dataset of environmental parameters for many agricultural
research applications.
INCLUDES THE FOLLOWING:
LI-1400 DataLogger
1400-301 Terminal Block
LI-200SA Pyranometer
1400-102 Air Temperature Sensor
1400-103 Soil Temperature Sensor
1400-106 Tipping Bucket Raingauge
1400-201 Vented Instrument Enclosure
1400-402 External Alkaline Battery Pack
2003S Mounting and Leveling Fixture
1400-550 RS-232 Communications Cable (9-pin to 9-pin)
Spare input channels allow you to add other LI-COR
sensors, or sensors from other manufacturers to create your
own customized system.
15

LI-1401 & LI-1405 SPECIFICATIONS:
LI-1400 DataLogger
Current Inputs: Five channels; three
through external sealed BNC connectors,
and two through the 1400-301
Standard Terminal Block.
Voltage Inputs: Four high impedance
(>500 Megohm) single-ended channels
accessed through the 1400-301
Terminal Block.
Pulse Counting Input: One pulse
counting channel. Switch closure for
tipping bucket rain gauge.
Logging Periods: Seconds: 1, 5, 15, 30. Minutes: 1, 5, 15,
30. Hours: 1, 3, 6, 12, 24.
Sampling Interval: Seconds: 1, 5, 15, 30.
Minutes: 1, 5, 15, 30, 60.
Keyboard: Sealed, 24 key tactile response keypad.
Display: Two line, 16 character alphanumeric LCD. Updated
once per second. Temperature compensated readability
from -15 to 55°C.
Internal Memory: 96K bytes available for data storage.
Program Memory: Stored in Flash memory for easy upgrades
via the RS-232C port.
Communications: RS-232C, hardwired Data Terminal
Equipment (DTE) through 9-pin port. Baud rates are software
selectable at 300, 1200, 2400, 4800 and 9600.
Communication is bi-directional.
External DC Power: 7 - 16 VDC.
Operating Conditions: -25 to 55 °C; 0 to 95% RH,
non-condensing.
1400-104 Air Temperature/ Relative Humidity Sensor
(LI-1401 only)
Air Temperature
Type: Platinum RTD
Accuracy: ± 0.8°C
Output: 0-1V = -40 to +60°C
Relative Humidity
Type: Capacitance
Accuracy: ±3% (10-90% RH)
Output: 0-1V = 0 to 100% RH
1400-105 Wind Direction/Speed Sensors (LI-1401 only)
Wind Direction
Type: Vane
Range: 0 to 360 degrees
Accuracy: ±5 degrees
Threshold: 2.9 mph
Output: 0-1V = 0 to 360 degrees
Wind Speed
Type: 3 cup
Range: 0 to 112 mph
Accuracy: ±1.1 mph
Threshold: 2.5 mph
Output: 0-1V = 0 to 100 mph
1400-106 Tipping Bucket Raingauge
Type: Tipping bucket
Output: 1 pulse mm -1 16
LI-200SA Pyranometer
Type: High stability silicon photovoltaic detector
Range: 0-1500 watts m -2
Output: Typically 90 µA (1000 w -1 m -2 )
Error: Typically ±5%
1400-102 Air Temperature Sensor (LI-1405 only)
1400-103 Soil Temperature Sensor
Type: Thermistor
Range: -40 to +50°C
Accuracy: ±0.5°C
Output: Temperature proportional to microamp current
using 5th order polynomial

OPTICAL RADIATION CALIBRATOR
• Spectral irradiance, irradiance, illuminance
and photon flux calibrations.
• For calibration of LI-COR Spectroradiometers,
quantum sensors and photometric sensors.
• Simple operation.
• Eliminates complex optical alignments and
expensive laboratory calibration equipment.
The 1800-02 is a self-contained optical radiation calibrator for
on-site spectral irradiance, irradiance, photon flux, or
illuminance calibrations in the 300-1100 nm wavelength range.
The 1800-02 integrates a quartz tungsten halogen lamp and a
highly regulated power supply into a portable package that acts
as an optical bench and darkroom. The 1800-02 can be
operated under normal lighting conditions and requires no
special facilities.
THE LAMP
The 1800-02 utilizes a 200 Watt quartz tungsten halogen lamp
operated at an approximate color temperature of 3150° Kelvin.
The tungsten halogen lamp provides the best available spectral
distribution for calibrations in the 300-1100 nm wavelength
range. Lamp calibrations are determined by using a temperature
controlled spectroradiometer to compare readings over the 300-
1100 nm wavelength range taken from the 1800-02 and the
working standard calibration lamp used in LI-COR's laboratory
calibration system. LI-COR's working standard quartz halogen
lamps have been calibrated against reference standard lamps
traceable to NIST. Calibration accuracy of the 1800-02 is
± 4.0% from 300-1100 nm.
POWER SUPPLY
The1800-02 has a highly regulated power supply which maintains
constant power to the lamp by regulating both current and
voltage. Regulating both current and voltage results in added
lamp stability.
When the 1800-02 is turned on, the lamp is powered up slowly
to prevent filament shock and a ready light indicates when the
lamp is within normal operating conditions. The lamp is protected
by a built-in over current protector which shuts off the
power supply in case of malfunction. Automatic shutoff also
occurs if the line voltage falls too low to maintain accurate regulation,
thereby preventing false calibration data. External jacks
for monitoring lamp current and voltage through a precision calibrated
shunt are provided to allow user verification of lamp stability.
OPERATION
Operation of the 1800-02 is a simple 3 step process.
1) Turn the 1800-02 on and allow 5 minutes after the
"ready” light comes on for the lamp to reach complete
thermal stability.
2) Install the sensor or spectroradiometer in the instrument
port using the appropriate mounting fixture (provided).
3) Read the sensor (or scan the lamp with a
spectroradiometer) and determine the calibration
constant from the lamp calibration data.
Sensor calibrations are performed using the sensor mounting fixture
which holds the sensor in a precise location and eliminates
the need to align the sensor within the calibration system. Both
terrestrial and underwater sensors can be calibrated using the
appropriate mounting fixture.
The 1800-02 can be used to recalibrate the LI-1800 Portable
Spectroradiometer, the LI-1800UW Underwater Spectroradiometer,
the 1800-11 Remote Cosine Receptor or the LI-COR
radiation sensors listed below.
Quantum: LI-190SB, LI-190SA, LI-190SZ
Underwater Quantum: LI-192SB, LI-192SA
Photometric: LI-210SB, LI-210SA, LI-210SZ
17

Operating Conditions: 0 to 50 C (± 0.25% total drift over this
range).
Power Requirements: 105-126/210-252 VAC,
48-66 Hz, 6 Amp/3 Amp.
Dimensions: 24.0 H × 27.0 W × 50.0 cm L
(9.5" H × 10.5" W × 19.5" L).
Weight: 16.0 Kg (35.0 lbs).
ORDERING INFORMATION
SPECIFICATIONS
Calibration Wavelength Range: 300-1100 nm.
Calibration Accuracy (traceable to NIST):
300 nm ± 6.0%
350-1000 nm ± 4.0%
1100 nm ± 6.0%
Lamp Type: 200 Watt Quartz Tungsten Halogen.
Lamp Life: Typically 50 hours with less than ± 1% change.
Calibrations take 7-10 minutes including 5 minutes for lamp
warm-up.
1800-02 Optical Radiation Calibrator: Includes one
1800-02L Calibrated Lamp, calibration data, mounting fixtures
for LI-COR terrestrial sensors, underwater sensors and
spectroradiometers.
1800-02L Calibrated Replacement Lamp:
For 1800-02 Optical Radiation Calibration.
Requires one for replacement.
1800-02RA Spectral Radiance Accessory: For spectral
radiance and radiance calibrations from 300-1100 nm.
A complete brochure is available on request.
PORTABLE SPECTRORADIOMETER
The LI-1800 Portable Spectroradiometer provides a fast, accurate
method to obtain spectral radiation measurements in the
field or in the laboratory. Its compact design, internal microcomputer,
and innovative optical design provide the versatility to
meet a wide variety of applications.
What can the LI-1800 do for you?
In remote sensing labs, the LI-1800 and 1800-12S External
Integrating Sphere are used to characterize the spectral
reflectance and transmittance of leaves. The data collected are
correlated with other remote sensing techniques.
LI-1800
• Direct readout of spectroradiometric, radiometric and
photometric measurements
• Direct readout of CIE chromaticity coordinates
• Fast scanning (over 30 nm s -1 )
• Internal microcomputer
• Up to 512K bytes RAM for data storage
• Weatherproof design, battery operation
At several field sites the LI-1800 is used for solar radiation monitoring.
These data are used to characterize solar radiation for
photovoltaic and energy conversion research, to generate solar
simulation models, and for weathering studies of materials and
coatings.
The LI-1800 is just as much at home in the lab as it is in the
field. Radiation quality and quantity are measured in growth
chambers and greenhouses for characterizing and verifying
radiation sources, and to correlate plant growth with spectral
output.
The LI-1800 is also well suited for many other laboratory, industrial,
and environmental applications including qualitative and
18

quantitative lamp measurements for photoresist processes, general
lamp evaluation, quality control, surface color measurements,
photochemistry and photobiology.
INNOVATIVE OPTICS
The measurement optics of the LI-1800 has three major components
— a filter wheel, holographic grating monochromator, and
a silicon detector. The filter wheel contains seven order-sorting
filters which eliminate second order harmonics and enhance
stray light rejection by filtering out radiation that is not in the
same spectral region as that being measured. The filter wheel
also has a black target that serves as a dark reference for each
scan.
The dispersing element is a holographic grating monochromator
which is available in two wavelength ranges; 300-850 nm with a
4 nm bandwidth and 300-1100 nm with a 6 nm bandwidth.
Optional monochromator slits are also available for changing the
bandwidth and sensitivity to meet your application.
The monochromator is driven by a precision stepping motor
under control of the internal microcomputer. Wavelength drive
intervals are user selectable at 1, 2, 5 or 10 nm. The LI-1800’s
high efficiency silicon detector and autoranging electronics
allow scanning rates of over 30 nm per second.
INTERNAL MICROCOMPUTER
The heart of the LI-1800 system is the internal microcomputer
which controls scanning and the collection, reduction and storage
of data. Communication with the LI-1800 is accomplished
using the 1800-01A Portable Terminal or any other RS-232
terminal or computer. The LI-1800 is easy to use, yet powerful.
A menu of simple commands covers all facets of operation from
scanning to data output.
SIMPLIFIED SCANNING
Scanning is accomplished by one command; however, the
LI-1800 lets you specify several parameters to get the scan you
want, including wavelength limits, wavelength drive interval,
and the number of scans to average. Averaging scans provides
accurate data under conditions of fluctuating radiation. Multiple
scan averaging also improves sensitivity (signal to noise ratio) in
low radiation conditions, since it reduces the noise level by a
factor approaching the square root of the number of scans.
After each scan the LI-1800 stores your data in its internal RAM
memory. Standard memory in the LI-1800 is 256K bytes and is
expandable to 512K bytes. The standard 256K memory typically
holds 200 scans from 300-1100 nm (2 nm steps) or 530 scans
from 400-700 nm.
DATA REDUCTION
The LI-1800’s built-in data reduction routines calculate irradiance,
radiance, CIE chromaticity coordinates, illuminance,
luminance, photon flux density, the ratio of spectral irradiance in
two regions of a scan, and more. A data file can also be plotted
on the 6000-03B Plotter/Printer using the LI-1800’s plotting
routine.
SPECIFICATIONS
Holographic Grating Monochromator Options
LI-1800/12 LI-1800/22
Wavelength Range: 300-850 nm 300-1100 nm
Standard Bandwidth
(1/2 mm slits): 4 nm 6 nm
Wavelength Accuracy: ± 1.5 nm ± 2 nm
Wavelength
Repeatability: ± 0.5 nm ± 0.5 nm
Linear Dispersion: 8 nm/mm 12 nm/mm
Grating:
1200 grooves/mm 800 grooves/mm
Automatic
Filter Wheel: 6 filters 7 filters
Noise Equivalent Irradiance
(Standard cosine receptor, W cm -2 nm -1 )
300-850 nm 300-1100 nm
300 nm 6 × 10 -8 7 × 10 -8
350 nm 4 × 10 -8 4 × 10 -8
400 nm 2.5 × 10 -8 1.5 × 10 -8
500-800 nm 8 × 10 -9 8 × 10 -9
800-850 nm 2.5 × 10 -8 —
800-1040 nm — 6 × 10 -9
1100 nm — 1.5 × 10 -8
Noise Equivalent Irradiance
(1800-11 Remote Cosine Receptor, W cm -2 nm -1 )
300-850 nm 300-1100 nm
350 nm 2 × 10 -7 2 × 10 -7
400 nm 1 × 10 -7 7 × 10 -8
500-800 nm 3 × 10 -8 3.5 × 10 -8
800-850 nm 1 × 10 -8 —
800-1040 nm — 3 × 10 -8
1100 nm — 6 × 10 -8
NOTE: NEI is the noise of the instrument detector and amplifier expressed in
terms of the irradiance necessary to generate a detector output of an equivalent
size. NEI values given are for standard 1/2 mm slits. Changing to 1 mm slits
typically increases the sensitivity and reduces the NEI 3 to 4 times. The 1/4 mm
slits decrease the sensitivity and increase the NEI 3 to 4 times.
Maximum Irradiance Levels (W cm -2 nm -1 )
300-400 nm 5 × 10 -3
400-1000 nm > 1 × 10 -3
Maximum irradiance levels are for 1/2 mm slits with standard
teflon cosine receptor and filters.
19

Wavelength Drive Intervals: 1, 2, 5 or 10 nm (user selectable).
Scanning: Single scan, multiple scans with automatic scan
averaging, or single wavelength monitoring (sampled once
per second).
Scanning Speed:
20 nm/second for 1 nm steps.
30 nm/second for 2 nm steps.
35 nm/second for 5 nm steps.
40 nm/second for 10 nm steps.
Total scan time for 300 to 1100 nm in 2 nm steps is 27 seconds.
Calibration: The LI-1800 is initially calibrated at the factory.
The 1800-02 Calibration System can be used for user recalibration,
or the LI-1800 can be returned for factory recalibration.
Calibration Accuracy:
300 nm ±10%
450 nm ± 5%
550 nm ± 4%
650-800 nm ± 3%
1100 nm ± 5% (under controlled conditions)
Calibration Stability: Typically

OPTICAL ACCESSORIES
1800-12S External Integrating Sphere: With the 1800-12S, the
LI-1800 becomes an even more powerful integrating sphere
based system for measurements ranging from total reflectance
and transmittance to color measurements of objects. Whether
you’re measuring leaf spectral properties in the field, or quality
control, the 1800-12S provides the portability to meet all your
measurement needs.
1
2
3
For measurements on thin samples, such as leaves, paper, or
cloth, the samples can be clamped onto the sample port for measurement.
For surface reflectance and color measurements of
larger objects, the sample clamp can be removed and the integrating
sphere placed directly on the object’s surface.
Measurements are taken by placing the illuminator in the reference
port and taking a reference scan with the LI-1800. Barium
sulfate (BaSO 4 ) is the reference material and is also used to coat
the walls of the 1800-12S. After a reference scan, the illuminator
is moved to the reflectance or transmittance port so the
source can shine on or through the object (respectively).
The reflectance or transmittance data files stored in the LI-1800
are then divided by the reference data file to produce a file
containing the total (diffuse plus specular) spectral reflectance or
transmittance. This data can also be used to calculate the CIE
chromaticity coordinates of the measured object by choosing
from standard sources A, E, D65 (stored in the LI-1800’s software)
or a user-entered standard.
Typical applications for the 1800-12S include leaf reflectance,
transmittance and absorptance in crop canopy studies; color
measurements and quality control of surface coatings, fabrics,
paper, and textiles. Other materials exhibiting marked directional
reflection differences due to surface texture can also be measured.
Integrating sphere geometry of the 1800-12S minimizes
the effects surface texture can have on the type of geometry used
in the measurement.
1800-06 Telescope/Microscope Receptor: Remote measurements
of spectral radiance, irradiance, luminance, illuminance,
reflectance, or color measurements are all possible using the
1800-06 Telescope-Microscope Receptor.
The 1800-06 consists of a receptor body to which a number of
optional lens accessories can be attached. A wide selection of
objective lenses and three field of view (FOV) apertures offer
flexibility in collecting radiant power from submillimeter objects
at close range, to large subjects at great distances. 35 mm
camera lenses can also be used for added flexibility.
The 1800-06 body has an internal reflex viewing mirror that
permits accurate, parallax-free viewing of the object to be
measured. A six position aperture wheel provides apertures
defining 3 different fields of view (for each lens option), a focusing
screen, a diffuser for viewing highly polarized sources, and a
dark position for checking the dark signal level.
1. 1800-06 Receptor Body
2. 1800-06B 3 Degree FOV Lens
3. 1800-12S External Integrating Sphere
The standard lens mount for the 1800-06 is a lockable sliding
tube which is used to mount and focus the optional lenses. The
standard lens mount can also be replaced by the optional 1800-
06D 35 mm camera lens mount (accepts Canon lenses with
bayonet type mounts).
Two telescopic lens options are available for the 1800-06; the
1800-06A 15 Degree FOV Accessory and the 1800-06B 3
Degree FOV Accessory. These options use quartz optics which
have good radiation transmission characteristics from 310-1100
nm. Both options A and B include an extension tube which
allows closer focusing.
Two lens options are also available for microscopic measurements.
The 1800-06C is a microscope lens mount which accepts
standard American Microscope Objects (AMO). Two objectives
are available from LI-COR, the 1800-06E (7x objective) and the
1800-06F (18x objective). Although any standard AMO objective
will mount to the 1800-06, field diameters of at least 0.8
mm are recommended if you wish to maintain full sensitivity of
the 1800-06.
The second microscope option is the quartz microscope which
uses components from the 1800-06A and 1800-06B telescopic
options to form a quartz microscope lens.
21

RADIATION MEASUREMENT
Much confusion has existed regarding the measurement of radiation.
This report presents a comprehensive summary of the
terminology and units used in radiometry, photometry, and the
measurement of photosynthetically active radiation (PAR).
Measurement errors can arise from a number of sources, and
these are explained in detail. Finally, the conversion of radiometric
and photometric units to photon units is discussed. In this
report, the International System of Units (SI) is used unless
noted otherwise (9).
RADIOMETRY
Radiometry (1) is the measurement of the properties of radiant
energy (SI unit: joule, J), which is one of the many interchangeable
forms of energy. The rate of flow of radiant energy, in the
form of an electromagnetic wave, is called the radiant flux (unit:
watt, W; 1 W = 1 J s -1 ) Radiant flux can be measured as it flows
from the source (the sun, in natural conditions), through one or
more reflecting, absorbing, scattering and transmitting media
(the Earth's atmosphere, a plant canopy) to the receiving surface
of interest (a photosynthesizing leaf) (8).
Terminology and Units
Radiant Flux is the amount of radiation coming from a source
per unit time. Unit: watt, W.
Radiant Intensity is the radiant flux leaving a point on the
source, per unit solid angle of space surrounding the point. Unit:
watts per steridian, W sr -1 .
Radiance is the radiant flux emitted by a unit area of a source or
scattered by a unit area of a surface. Unit: W m -2 sr -1 .
Irradiance is the radiant flux incident on a receiving surface
from all directions, per unit area of surface. Unit: W m -2 .
Absorptance is the fraction of the incident flux that is absorbed
by a medium.
Reflectance and Transmittance are equivalent terms for the
fractions that are reflected or transmitted.
Spectroradiometry: All the properties of the radiant flux
depend on the wavelength of the radiation. The prefix spectral is
added when the wavelength dependency is being described.
Thus, the spectral irradiance is the irradiance at a given
wavelength, per unit wavelength interval. The irradiance within
a given waveband is the integral of the spectral irradiance with
respect to wavelength (8). Unit: W m -2 nm -1 . Spectral measurements
can be made using the LI-1800 Portable Spectroradiometer.
Global solar radiation is the solar irradiance received
on a horizontal surface (also referred to as the direct component
of sunlight plus the diffuse component of skylight received
together on a horizontal surface). This physical quantity is measured
by a pyranometer such as the LI-200SA. Unit: W m -2 .
Direct Solar Radiation is the radiation emitted from the solid
angle of the sun's disc, received on a surface perpendicular to the
axis of this cone, comprising mainly unscattered and unreflected
solar radiation. This physical quantity is measured by a
pyrheliometer. Unit: W m -2 .
Diffuse Solar Radiation (sky radiation) is the downward
scattered and reflected radiation coming from the whole
hemisphere, with the exception of the solid angle subtended by
the sun's disc. Diffuse radiation can be measured by a
pyranometer mounted on a shadow band, or calculated using
global solar radiation and direct solar radiation. Unit: W m -2 .
PHOTOSYNTHETICALLY
ACTIVE RADIATION
In the past there has been disagreement concerning units and
terminology used in radiation measurements in conjunction with
the plant sciences. It is LI-COR's policy to adopt the recommendations
of the international committees, such as the Commission
Internationale de I'Eclairage (CIE), the International Bureau of
Weights and Measures, and the International Committee on
Radiation Units. The International System of Units (SI) should
be used wherever a suitable unit exists (9).
Units
The SI unit of radiant energy flux is the watt (W). There is no
official SI unit of photon flux. A mole of photons is commonly
used to designate Avogadro's number of photons (6.022 × 10 23
photons). The einstein has been used in the past in plant science,
however, most societies now recommend the use of the mole
since the mole is an SI unit. When either of these definitions is
used, the quantity of photons in a mole is equal to the quantity
of photons in an einstein (1 mole = 1 einstein = 6.022 × 10 23
photons). Note: The einstein has also been used in books on
photochemistry, photobiology and radiation physics as the quantity
of radiant energy in Avogadro's number of photons (5). This
definition is not used in photosynthesis studies.
Terminology
LI-COR continues to follow the lead of the Crop Science
Society of America, Committee on Terminology (10) and other
societies (11) until international committees put forth further
recommendations.
22

®
Photosynthetically Active Radiation (PAR) is defined as radiation
in the 400 to 700 nm waveband. PAR is the general radiation
term which covers both photon terms (7) and energy terms.
Photosynthetic Photon Flux Density (PPFD) is defined as the
photon flux density of PAR, also referred to as Quantum Flux
Density. This is the number of photons in the 400-700 nm
waveband incident per unit time on a unit surface. The ideal
PPFD sensor responds equally to all photons in the 400-700 nm
waveband and has a cosine response. This physical quantity is
measured by a cosine (180˚) quantum sensor such as the
LI-190SA or LI-192SA. The LI-191SA Line Quantum Sensor
also measures PPFD. Figure 1 shows an ideal quantum response
curve and the typical spectral response curve of LI-COR quantum
sensors.
Units: 1 µmol s -1 m -2 ≡ 1 µE s -1 m -2 ≡ 6.022 • 10 17 photons s -1 m -2 .
PERCENT RELATIVE RESPONSE
100
80
60
40
20
0
ULTRAVIOLET
LI-COR
QUANTUM SENSOR
VIOLET
BLUE
IDEAL QUANTUM RESPONSE
GREEN
400 500 600 700
Figure 1. Typical spectral response of LI-COR Quantum
Sensors and a photosynthetic irradiance sensor vs.
wavelength and ideal quantum response.
Photosynthetic Photon Flux Fluence Rate (PPFFR) LI-COR
introduced this term which is defined as the photon flux fluence
rate of PAR, also referred to as Quantum Scaler Irradiance or
Photon Spherical Irradiance. This is the integral of photon flux
radiance at a point over all directions about the point. The ideal
PPFFR sensor has a spherical collecting surface which exhibits
the properties of a cosine receiver at every point on its surface
(Figure 2) and responds equally to all photons in the 400-700 nm
waveband (Figure 1). This physical quantity is measured by a
spherical (4π collector) quantum sensor such as the LI-193SA.
Units: 1 µmol s -1 m -2 ≡ 1 µE s -1 m -2 ≡ 6.022 × 10 17 photons s -1 m -2
≡ 6.022 • 10 17 quanta s -1 m -2 .
Note: There is no unique relationship between the PPFD and the
PPFFR. For a collimated beam at normal incidence, they are
equal; while for perfectly diffuse radiation, the PPFFR is 4 times
the PPFD. In practical situations the ratio will be somewhere
between 1 and 4.
YELLOW
WAVELENGTH – NANOMETERS
RED
INFRARED
Ø= 270°
PHOTOMETRY
Figure 2. Typical
Angular Response of the
LI-193SB Spherical
Quantum Sensor.
Photometry refers to the measurement of visible radiation (light)
with a sensor having a spectral responsivity curve equal to the
average human eye. Photometry is used to describe lighting
conditions where the eye is the primary sensor, such as illumination
of work areas, interior lighting, television screens, etc.
Although photometric measurements have been used in the past
in plant science, PPFD and irradiance are the preferred measurements.
The use of the word "light" is inappropriate in plant
research. The terms "ultraviolet light" and "infrared light"
clearly are contradictory (8).
The spectral responsivity curve of the standard human eye at
typical light levels is called the CIE Standard Observer Curve
(photopic curve), and covers the waveband of 380-770 nm. The
human eye responds differently to light of different colors and
has maximum sensitivity to yellow and green (Figure 3). In
order to make accurate photometric measurements of various
colors of light or from differing types of light sources, a
photometric sensor's spectral responsivity curve must match
the CIE photopic curve very closely.
PERCENT RELATIVE RESPONSE
100
80
60
40
20
0
ULTRAVIOLET
VIOLET
Ø= 0°
8
6
4
2
Ø= 180°
PHOTOMETRIC
SENSOR
BLUE
GREEN
Ø= 90°
400 500 600 700
Figure 3. Typical spectral response of LI-COR Photometric
Sensors vs. the CIE photopic response curve.
YELLOW
WAVELENGTH – NANOMETERS
CIE PHOTOPIC CURVE
RED
INFRARED
23

ENVIRONMENTAL DIVISION
Terminology and Units (4)
Luminous Flux is the amount of radiation coming from a source
per unit time, evaluated in terms of a standardized visual
response. Unit: lumen, lm.
Luminous Intensity is the luminous flux per unit solid angle in
the direction in question. Unit: candela, cd. One candela is one
lm sr -1 .
Luminance is the quotient of the luminous flux at an element of
the surface surrounding the point and propagated in directions
defined by an elementary cone containing the given direction, by
the product of the solid angle of the cone and the area of the
orthogonal projection of the element of the surface on a plane
perpendicular to the given direction. Unit: cd m -2 ; also,
lm sr -1 m -2 . This unit is also called the nit.
Illuminance is defined as the density of the luminous flux
incident at a point on a surface. Average illuminance is the
quotient of the luminous flux incident on a surface by the area
of the surface. This physical quantity is measured by a cosine
photometric sensor such as the LI-210SA.
Unit: lux, lx. One lux is one lm m -2 .
MEASUREMENT ERRORS
At a Controlled Environments Working Conference in Madison,
Wisconsin, USA (1979), an official from the U.S. National
Bureau of Standards (NBS) stated that one could not expect less
than 10 to 25% error in radiation measurements made under
non-ideal conditions. In order to clarify this area, the sources of
errors which the researcher must be aware of when making
radiation measurements have been tabulated. Refer also to the
specifications given with each sensor for further details.
Absolute Calibration Error
Absolute calibration error depends on the source of the lamp
standard and its estimated uncertainty at the time of calibration,
accuracy of filament to sensor distance, alignment accuracy,
stray light, and the lamp current measurement accuracy. Where
it is necessary to use a transfer sensor (such as for solar calibrations)
additional error will be introduced. LI-COR quantum and
photometric sensors are calibrated against a working quartz
halogen lamp. These working quartz halogen lamps have been
calibrated against laboratory standards traceable to the NBS.
Standard lamp current is metered to 0.035% accuracy.
Microscope and laser alignment in the calibration setup reduce
alignment errors to less than 0.1%. Stray light is reduced by
black velvet to less than 0.1%. The absolute calibration
accuracy is limited to the uncertainty of the NBS traceable
standard lamp. The absolute calibration specification for
LI-COR sensors is ±5% traceable to the NBS. This accuracy is
conservatively stated and the error is typically ±3%. Absolute
calibrations and spectral responses of LI-COR sensors have been
checked by the National Research Council of Canada (NRC) to
insure the accuracy and quality of LI-COR calibrations.
Relative Error (Spectral Response Error)
This error is also called actinity error or spectral correction error.
This error is due to the spectral response of the sensor not
conforming to the ideal spectral response. This error occurs
when measuring radiation from any source which is spectrally
different than the calibration source.
The quantum and photometric sensor spectral response conformity
is checked by LI-COR using a monochromator and calibrated
silicon photodiode. The spectral response of the sensor is
achieved by the use of computer-tailored filter glass. Relative
errors for various sources due to a non-ideal spectral response
are checked by actual measurement and a computer program
which utilizes the source spectral irradiance data and the sensor
spectral response data.
The relative error specifications given for LI-COR quantum
and photometric sensors are for use in growth chambers,
daylight, greenhouses, plant canopies and aquatic conditions.
When used with sources that have strong spectral lines such
as gas lamps or lasers, this error could be larger depending
on the location of the lines.
The LI-COR pyranometer measures irradiance from the sun plus
sky. The LI-200SA is not spectrally ideal (equal spectral
response from 280-2800 nm). See Figure 4. Therefore, it
should be used only under natural, unobstructed daylight
conditions. NOAA states in a test report that for clear, unobstructed
daylight conditions, the LI-COR pyranometer compares
very well with class one thermopile pyranometers (3). The
LI-200SA is a WMO (World Meteorological Organization) class
two pyranometer.
The LI-200SA should not be used under spectrally different radiation
(than the sun), such as in growth chambers, greenhouses,
and plant canopies. Under such artificial or shaded conditions, a
thermopile pyranometer should be used.
SPECTRAL IRRADIANCE (Sλ) - W m -2 A -1
0.25
0.20
0.15
0.10
0.05
SOLAR IRRADIATION CURVE OUTSIDE ATMOSPHERE
SOLAR IRRADIATION CURVE AT SEA LEVEL
CURVE FOR BLACKBODY CT 5900°K
0 3
H O 2
0 H O 2 2
® PYRANOMETER SENSOR
H O 2
H O 2H
O
2
H O 2
H O, CO
2 2
0 3
50
H O, CO
2 2 H O, CO
2 2
0 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2
WAVELENGTH ( µ )
Figure 4. The LI-200SA Pyranometer spectral
response is illustrated along with the energy distribution
in the solar spectrum (5).
100
PERCENT RELATIVE RESPONSE TO IRRADIANCE
24

Spatial Error
This error is caused by a sensor not responding to radiation at
various incident angles. Spatial error consists of the cosine error
(or the angular error) and azimuth error.
Cosine Error
A sensor with a cosine response (follows Lambert's cosine
law) allows measurement of flux densities through a given
plane, i.e. flux densities per unit area. When a parallel beam
of radiation of given cross-sectional area spreads over a flat
surface, the area that it covers is inversely proportional to
the cosine of the angle between the beam and a plane nor
mal to the surface. Therefore, the irradiance due to the beam
is proportional to the cosine of the angle. A radiometer,
whose response to beams coming from different directions
follows the same relationship, is said to be "cosine-corrected"
(6). A sensor without an accurate cosine correction can
give a severe error under diffuse radiation conditions within
a plant canopy, at low solar elevation angles, under fluorescent
lighting, etc.
Cosine response is measured by placing the sensor on a
platform which can be adjusted to rotate the sensor about an
axis placed across the center of the measuring surface. A
collimated source is directed at normal incidence and the
output of the sensor is measured as the angle of incidence is
varied. The cosine error at angle 0 is the percent difference
of the ratio of the measured output at angle 0 and normal
incidence (angle 0°) as compared to the cosine of angle 0.
This is repeated for various azimuth angles as necessary.
The LI-190SA, LI-200SA and LI-210SA are fully corrected
cosine sensors. These sensors have a typical cosine error of
less than 5% up to an 80° angle of incidence. Totally diffuse
radiation introduces a cosine error of approximately 2.5%.
For sun plus sky at a sun elevation of 30° (60° angle of
incidence), the error is ≈2%. The LI-192SA sensor has a
slightly greater cosine error since this sensor has a cosine
response optimized for both air and water. The LI-191SA
uses uncorrected acrylic diffusers and has a greater error at
high angles of incidence. For totally diffuse radiation, the
error is ≈8%. For conditions within canopies, the error is
less because the radiation is not totally diffuse.
Angular Error
A spherical PPFFR sensor measures the total flux
incidence on its spherical surface divided by the crosssectional
area of the sphere. Angular error is measured by
directing a collimated source at normal incidence and
rotating the sensor 360° about an axis directly through the
center of the sphere at 90° from normal incidence. This is
repeated for various azimuth angles as necessary to
characterize the sensor.
The LI-193SA angular error is due to variations in density
in the diffusion sphere and the sphere area lost because of
the sensor base (Figure 2). This error is less than -10% for
total because the upwelling radiation is much smaller than
the downwelling radiation.
Azimuth Error
This is a subcategory of both cosine and angular error. It is
specified separately at a particular angle of incidence. This
error is the percent change of the sensor output as the sensor
is rotated about the normal axis at a particular angle of
incident radiation. This error is less than ±1% at 45° for the
LI-190SA, LI-192SA, LI-200SA, and LI-210SA sensors.
The error is less than ±3% for the LI-191SA and LI-193SA
sensors.
Displacement Error
In highly turbid waters, the LI-193SA Spherical Sensor will indicate
high PPFFR values due to the displacement of water by the
sensor sphere volume. This is because the point of measurement
is taken to be at the center of the sphere, but the attenuation
which would have been provided by the water within the sphere
is absent. This error is typically +6% for water with an attenuation
coefficient of 3 m -1 (2).
Tilt Error
Tilt error exists when a sensor is sensitive to orientation due
to the effects of gravity. This exists primarily in thermopile
type detectors. Silicon type detectors do not have this error.
All LI-COR sensors are of the latter type and have no tilt error.
This error in the LI-200SA Pyranometer is nonexistent and has
an advantage over thermopile type detectors for solar radiation
measurements (3).
Linearity Error
Linearity error exists when a sensor is not able to follow proportionate
changes in radiation. The type of silicon detectors used in
LI-COR sensors have a linearity error of less than ±1% over
seven decades of dynamic range.
Fatigue Error
Fatigue error exists when a sensor exhibits hysteresis. This is
common in selenium-based illumination meters and can add a
considerable error. For this reason, LI-COR sensors incorporate
only silicon detectors which exhibit no fatigue error.
Temperature Coefficient Error
Temperature coefficient error exists when the output of a sensor
changes with a constant input. This error is typically less than
±0.1% per °C for the LI-190SA, LI-191SA, LI-192SA,
25

LI-193SA, and LI-210SB sensors. This error is slightly higher
for the LI-200SA.
Response Time Error
This error exists when the source being measured changes
rapidly during the period of measurement.
Averaging:
Large errors can exist when measuring radiation
under rapidly changing conditions such as changing cloud
cover and wind if measuring within a crop canopy, and
waves if measuring underwater. The use of an integrating
meter to average the reading will eliminate this error.
Instantaneous:
When radiation measurements are desired over a period of
time (much less than the response time of the system), large
errors can exist. For example, if one were to measure the
radiation from a pulsed source (such as a gas discharge flash
lamp) with a typical system designed for environmental
measurements, the reading would be meaningless. Such a
measurement should not be made with LI-COR instruments
without consultation with LI-COR.
Long-Term Stability Error
This error exists when the calibration of a sensor changes with
time. This error is usually low for sensors using high quality
silicon photovoltaic photodiodes and glass filters. LI-COR uses
only high quality components. The use of Wratten filters and/or
inexpensive silicon or selenium cells add significantly to longterm
stability error. The stability error of LI-COR sensors is typically
±2% per year.
Important: Customers should have their sensors recalibrated
every two years.
Immersion Effect Error
A sensor with a diffuser for cosine correction will have an
immersion effect when used under water. Radiation entering the
diffuser scatters in all directions within the diffuser, with more
radiation lost through the water-diffuser interface than in the
case when the sensor is in the air. This is because the airdiffuser
interface offers a greater ratio of indices of refraction
than the water-diffuser interface. LI-COR provides a typical
immersion effect correction factor for the underwater sensors.
Immersion effect error is the difference between this typical
figure and the actual figure for a given sensor in a particular
environment. Since LI-COR test measurements are done in clear
water, the error is also dependent on other variables such as
turbidity, salinity, etc. Immersion effect error is typically ±2%
or less. A complete report on the immersion effect properties of
LI-COR underwater sensors is available from LI-COR.
Surface Variation Error
In general, the absolute responsivity and the relative spectral
responsivity are not constant over the radiation-sensitive surface
of sensors. This error has little effect in environmental measurements
except for spatial averaging sensors such as the
LI-191SA. This error is < ±7% for the LI-191SA.
User Errors
Spatial User Error
This is different than sensor-caused spatial error.
Spatial user error can be introduced by using a single small
sensor to characterize the radiation profile within a crop
canopy or growth chamber. The flux density measured on a
given plane can vary considerably due to shadows and
sunflecks. To neglect this in measurements can introduce
errors up to 1000%. Multiple sensors or sensors on track
scanners can be used to minimize this error. If track
scanners are used, the output of the sensors must be
integrated.
The LI-191SA Line Quantum Sensor, which spatially
averages radiation over its one meter length, minimizes this
error and allows one person to easily make many measurements
in a short period of time. Another method, although
not as accurate, is to use an integrating meter and the
LI-190SA quantum Sensor and physically scan the sensor
by hand within the canopy while integrating the output with
the meter.
Another type of spatial user error can be caused by
misapplication of a cosine-corrected sensor where a
spherical sensor would give a more accurate measurement.
An example is in underwater photosynthetic radiation
measurements when studying phytoplankton.
User Setup/Application Errors
These errors include such causes as:
• Reflections or obstructions from clothing, buildings,
boats, etc.
• Dust, flyspecks, seaweeds, bird droppings, etc.
• Shock, causing permanent damage of optics within
the sensor.
• Submersion of terrestrial sensors in water for an
extended period (partial or total). Rain doesn't affect
the sensors since they are completely weatherproof.
• Use of the incorrect calibration constant.
• Incorrect interpolation of analog meters.
• Using the wrong meter function.
• Failure to have sensors recalibrated periodically.
26

Readout Error
This error is due to the readout instrument as distinguished from
the sensor. Zero drift, temperature, battery voltage, electronic
stability, line voltage, humidity and shock are all factors which
can contribute to readout error. The use of electronic circuitry
such as chopper-stabilized amplifiers and voltage regulators in
LI-COR meters largely eliminates many of these problems: zero
drift, temperature, battery voltage, electronic stability, line
voltage.
Total Error
The errors given are largely independent of each other and are
random in polarity and magnitude. Therefore, they can be
summed in quadrature (the square root of the sum of the
squares). The total error is shown below for an LI-190SA
Quantum Sensor and LI-COR meters when used for measuring
lighting in a typical growth chamber or natural daylight over a
temperature range of 15° to 35°C.
Typical Error
Absolute Error
5% max., 3% typical
Relative (spectral response) Error 5%
Spatial (cosine) Error 2%
Displacement Error 0%
Tilt Error 0%
Linearity Error 0%
Fatigue Error 0%
Sensor Temperature Coefficient Error 1 % (0.1% per °C)
Response Time Error 0%
Long-term Stability Error
2% (2% per year)
Immersion Effect Error 0%
Surface Variation Error 0%
Readout Error 1%
User Error ?
The total error = Square Root (5 × 5 + 5 × 5 + 2 × 2 + 1 × 1) =
7.6%. All of the above errors are minimized by LI-COR through
design and calibration. While this error seems reasonably low, it
must be remembered that no user error has been added, and that
statistically it is possible that all the errors could be of the same
polarity. The sum of the errors (less the user error) could equal
21% in the worst case. The absolute error is conservatively stated
and is more typically ±3%. User error in vegetation canopies
where shadows and sunflecks exist can be very large (1000%)
and one of the methods described under Spatial User Error
should be employed.
When purchasing a radiation measuring system, it is necessary
to insure that the spatial (cosine, etc.) and relative spectral
response errors are as low as possible. These two errors depend
upon the skill and expertise of the designer and manufacturer.
Some manufacturers deliberately do not give specifications for
these errors and the user can expect large errors. The absolute
error is largely dependent on the NBS lamp standard.
Minimization of this error can be achieved by the more experienced
companies through the use of precise techniques and
expensive capital equipment. In order to insure long-term
stability, it is necessary that the manufacturer use the highest
quality silicon photovoltaic/photodiodes and only the best glass
filters. Modern electronic readout instruments virtually eliminate
readout error.
The user should be aware of all the types of errors that can
occur, particularly the relative and spatial errors, since these can
add considerably to the total error. LI-COR has and continues to
put forth a considerable effort to insure that the spectral and
cosine response of all quantum and photometric sensors are as
nearly ideal as optically possible. This assures LI-COR
customers of the best possible accuracy.
CONVERSION OF UNITS
Conversion of Photon Units to Radiometric Units
Conversion of quantum sensor output in µmol s -1 m -2 (400-700
nm) to radiometric units in W m -2 (400-700 nm) is complicated.
The conversion factor will be different for each light source, and
the spectral distribution curve of the radiant output of the source
(W λ ; W m -2 nm -1 ) must be known in order to make the conversion.
The accurate measurement of W λ is a difficult task, which
should not be attempted without adequate equipment and calibration
facilities. The radiometric quantity desired is the integral
of W λ over the 400-700 nm range, or:
700
W = W d
∫ λ λ
1.
T
At a given wavelength λ, the number of photons per second is:
where h = 6.63 • 10 -34 J•s (Planck's constant), c = 3.00 • 10 8 m s -1
(velocity of light) and λ is in nm. hc/λ is the energy of one photon.
Then, the total number of photons per second in the 400-
700 nm range is:
700 W
d
∫ hc /
λλ λ
3.
This is the integral which is measured by the sensor. If R is the
reading of the quantum sensor in µmol s -1 m -2 (1 µmol s -1 m -2 ≡
6.022 • 10 17 photons s -1 m -2 ), then:
400
W
photons s
-1 λ
=
hc/ λ
400
700
17 W
6.022 × 10 (R) =
λ
∫ 400 hc/ λ
dλ
Combining Eq. (1) and Eq. (4) gives
700
Wd
17 ∫ λ λ
400
WT
= 6.022 × 10 (RHc)
5.
700
λWd
∫ λ λ
400
To achieve the two integrals, discrete summations are necessary.
Also, since W λ appears in both the numerator and the denominator,
the normalized curve N λ may be substituted for it. Then:
∑
Nλ
∆λ
i
17 i
WT
= 6.022 × 10 (RHc)
∑λiNλ
∆λ
i
i
2.
4.
6.
27

where ∆λ is any desired wavelength interval, λ i is the center
wavelength of the interval and N λi is the normalized radiant
output of the source at the center wavelength. In final form this
becomes:
∑Nλi
i W T (R)
N
W m -2
≈ 119.
8
7.
where R is the reading in µmol s -1 m -2 .
The following procedure should be used in conjunction
with Eq. (7).
1 . Divide the 400-700 nm range into 'i' intervals of
equal wavelength spacing ∆λ.
2. Determine the center wavelength (λ i ) of each
interval.
3. Determine the normalized radiant output of the
source (N λi
) at each of the center wavelengths.
4. Sum the normalized radiant outputs as determined
in Step 3 to find
∑
Nλ
i
5. Multiply the center wavelength by the normalized
radiant output at that wavelength for each interval.
6. Sum the products determined in Step 5 to find
7. Use Eq. (7) to find W T in W m -2 , where R is the
quantum sensor output in µmol s -1 m -2 .
The following approximation assumes a flat spectral distribution
curve of the source over the 400-700 nm range (equal spectral
irradiance over the 400-700 nm range) and is shown as an
example.
Given: i = 1
∆λ = 300 nm
λ i = 550 nm
i
This conversion factor is within ±8.5% of the factors determined
by McCree as listed in Table 1 (8).
Conversion of Photon Units to Photometric Units
∑
⎛ N(550) ⎞ 119.
8 (R)
-2
WT
≈ 119.8 (R) ⎜
⎟ = = 022 . (R) W m
⎝ 550 × N(550) ⎠ 550
or
1W m -2 ≈ 4.6 µmol s -1 m -2
∑
i
λ i
λ
i
i
λ
iNλ
i
where y λ is the luminosity coefficient of the standard CIE
curve with y λ = 1 at 550 nm and W λ is the spectral irradiance
(W m -2 nm -1 ).
b) Replace Eq. (5) with
700
y W d
17 ∫ λ λ λ
400
Lux = 683 (6.022 × 10 ) (RHc)
700
λWd
∫ λ λ
400
c) Replace Eq. (6) with
y N ∆λ
d) Replace Eq. (7) with
Lux = 8.17×
10 (R)
∑λ
Nλi
e) Replace Step 4 with:
i
4a) Multiply the luminosity coefficient (y λ ) of the
center wavelength by the normalized radiant
output (N λ ) at the wavelength for each interval
4b). Sum the products determined in Step 4a to find
The following approximation assumes a flat spectral distribution
curve of the source over the 400-700 nm range (equal spectral
irradiance over the 400-700 nm range) and shown as an
example.
Given:
i = 1 to 31
∆λ = 10 nm
λ 1 = 400, λ 2 = 410, λ 3 = 420.... λ 31 = 700
Ν λ = 1 for all wavelengths
y λ1
= 0.0004, y λ2
= 0.0012, y λ3
= 0.004....y λ31
= 0.0041
Or,
17
Lux = 683 (6.022 × 10 ) (RHc)
1000 lux = 1 klux = 19.5 µmol s -1 m -2
Table 1. Approximate conversion factors for various light
sources.
(8) (PAR waveband 400-700 nm)
To convert
∑
i
4
∑
∑
i
∑
λ
i
λ
λiNλ
∆λ
i
i
∑
i
yλ
Nλ
i
i
yλ
Nλ
yλi
4 i
10.682
Lux = 8.17× 10 (R) = 817 . × 10 (R)
⎛ ⎞
⎝ 17050 ⎠
∑
4
λi
i
Lux = 51.2 R, where R is in µmol s -1 m -2
Light Source
Daylight Metal Sodium Mercury White Incand.
halide (HP) fluor.
Multiply by
i
i
i
To convert photon units (µmol s -1 m -2 , 400-700 nm) to photometric
units (lux, 400-700 nm), use the above procedure, except
a) Replace Eq. (1) with
700
Lux = 683 y W d
∫ λ λ λ
400
Wm -2 (PAR) to 4.6 4.6 5.0 4.7 4.6 5.0
µmol s -1 m -2 (PAR)
klux to 18 14 14 14 12 20
µmol s -1 m -2 (PAR)
klux to W m -2 (PAR) 4.0 3.1 2.8 3.0 2.7 4.0
28

Your comments on the subjects addressed in this report or any
other measurement problems are always welcome and will be
treated as valuable inputs.
William W. Biggs, Author
Excerpted from: Advanced Agricultural Instrumentation.
Proceedings from the NATO Advanced Study Institute on
“Advanced Agricultural Instrumentation”, 1984. W.G. Gensler
(ed.), Martinus Nijhoff Publishers, Dordrect, The Netherlands.
RADIATION MEASUREMENT REFERENCES
1. CIE (Commission Internationale de l’Eclairage). 1970.
International lighting vocabulary, 3rd edn. Bureau Central
de la CIE. Paris
2. Combs, W.S., Jr., 1977. The measurement and prediction of
irradiances available for photosynthesis by phytoplankton in
lakes. Ph.D. Thesis, Univ. of Minnesota, Limnology.
3. Flowers, E.C. 1978. Comparison of solar radiation sensors
from various manufacturers. In: 1978 annual report from
NOAA to the DOE.
4. Illuminating Engineering Society of North America. 1981.
Nomenclature and definitions for illuminating engineering.
Publication RP-16, ANSI/IES RP-116-1980. New York.
5. Incoll, L.D., S.P. Long and M.A. Ashmore. 1981. SI units in
publications in plant science. In: Commentaries in Plant Sci.
Vol. 2, pp. 83-96, Pergamon, Oxford.
6. Kondratyev, K. Ya. 1969. Direct solar radiation. In:
Radiation in the atmosphere. Academic Press, New York,
London.
7. McCree, K.J. 1972. Test of current definitions of photosynthetically
active radiation against leaf photosynthesis
data. Agric. Meteorol. 10:443-453.
8. _________. 1981. Photosynthetically active radiation. In:
Physiological plant ecology. Lang, O.L., P. Novel, B.
Osmond and H. Ziegler (ed). Vol. 12A, Encyclopedia of
plant physiology (new series). Springer-Verlag. Berlin,
Heidelberg, New York.
9. Page, C.H. and P. Vigoureux (ed). 1977. The international
system of units (SI). Nat. Bur. of Stand. Special Publ. 330,
3rd edn. U.S. Govt. Printing Office, Washington D.C.,
U.S.A.
10. Shibles, R. 1976. Committee Report. Terminology pertaining
to photosynthesis. Crop Sci. 16:437-439.
11. Thimijan, R.W., and R.D. Heins. 1983. Photometric, radio
metric, and quantum light units of measure: a review of
procedures for interconversion. HortScience 18:818-822.
BROCHURE REFERENCES
1. Biggs, W.W., A.R. Edison, J.D. Easton, K.W. Brown,
J.W. Maranville and M.D. Clegg. 1971. Photosynthesis
light sensor and meter. Ecology 52:125-131.
2. De Wit, C. T. 1965. Photosynthesis of leaf canopies. Agric.
Res. Rep. No. 663. Institute for Bio. and Chem. Res. on
Field Crops and Herbage. Wageningen, The Netherlands.
3. Federer, C.A. and C.B. Tanner. 1966. Sensors for
measuring light available for photosynthesis.
Ecology 47:654-657.
4. Hesketh, J., and D. Baker. 1967. Light and carbon assimilation
by plant communities. Crop Sci. 7:285-293.
5. Flowers, E.C. 1978. Comparison of solar radiation sensors
from various manufacturers. In: 1978 annual report from
NOAA to the DOE.
6. Incoll, L.D., S.P. Long and M.R. Ashmore. 1981. SI units
in publications in plant science. In: Commentaries in
Plant Sci. Vol. 2, pp. 83-96, Pergamon, Oxford.
7. Kerr, J.P., G.W. Thurtell and C.B. Tanner. 1967. An integrating
pyranometer for climatological observer stations and
mesoscale networks. J. Appl. Meterol. 6:688-694.
8. Kondratyev, K. Ya. 1969. Direct solar radiation. Radiation
in the atmosphere. Academic Press, New York-London
9. McCree, K.J. 1972. Test of current definitions of photosynthetically
active radiation against leaf photosynthesis
data. Agric. Meteorol. 10:443-453.
10. Monteith, J.L. 1977. Climate and efficiency of crop production
in Britain. Philos. Trans. R. Soc. London, Ser. B.
281:277-294.
11. Palmiter, L.S., L.B. Hamilton, M.J. Holtz. 1979. Low cost
performance evaluation of passive solar buildings. SERI/RR-
63-223. UC-59B.
12. Rabinowitch, E.E. 1951. Photosynthesis and related
processes. Inter-science. New York. 2088 pages.
13. Ritchie, J.T. 1980. Climate and Soil Water. In: Moving up
the yield curve: Advances and obstacles. ASA Spec. Pub.
No. 39:1-23. Stelly, M., L. S. Murphy, L. F. Welch, E. C.
Doll (Ed). Amer. Soc. Agron./Soil Sci. Soc. Amer.
14. Shibles, R. 1976. Committee Report: Terminology
pertaining to photosynthesis. Crop Sci. 16:437-439.
29

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