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RADIATION<br />
MEASUREMENT<br />
INSTRUMENTS<br />
Radiation Sensors<br />
Data Loggers<br />
Light Meters<br />
Meteorological Stations<br />
Spectroradiometers<br />
Ca<strong>li</strong>brators<br />
®
Table of Contents<br />
LI-190SA Quantum Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . .1<br />
LI-191SA Line Quantum Sensor . . . . . . . . . . . . . . . . . . . . . . .2<br />
Underwater PAR Measurement . . . . . . . . . . . . . . . . . . . . . . . .3<br />
LI-192SA Underwater Quantum Sensor . . . . . . . . . . . . . . .3<br />
LI-193SA Spherical Quantum Sensor . . . . . . . . . . . . . . . . .3<br />
LI-200SA Pyranometer Sensor . . . . . . . . . . . . . . . . . . . . . . . . .5<br />
LI-210SA Photometric Sensor . . . . . . . . . . . . . . . . . . . . . . . . .6<br />
Sensor Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7<br />
LI-250 Light Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8<br />
LI-1400 DataLogger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10<br />
LI-1401 Agro Meteorological System . . . . . . . . . . . . . . . . . . . .14<br />
LI-1405 Basic Weather Station . . . . . . . . . . . . . . . . . . . . . . . . .15<br />
Optical Radiation Ca<strong>li</strong>brator . . . . . . . . . . . . . . . . . . . . . . . . . . .17<br />
LI-1800 Portable Spectroradiometer . . . . . . . . . . . . . . . . . . . . .18<br />
Radiation Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22<br />
“Trust in the LORD with all your heart; and do not lean on your own understanding. In all your ways acknowledge Him, and He<br />
will make your path straight.”Proverbs 3:5,6<br />
The LI-COR Board of Directors would <strong>li</strong>ke to take this opportunity to return thanks to God for His merciful providence in allowing<br />
LI-COR to develop and commercia<strong>li</strong>ze products, through the collective effort of dedicated employees, that enable the examination of<br />
the wonders of His works.
LI-190SA QUANTUM SENSOR<br />
LI-190SA QUANTUM SENSOR<br />
MEASURE PHOTOSYNTHETICALLY<br />
ACTIVE RADIATION<br />
During photosynthesis, plants use energy in the region of the<br />
electromagnetic spectrum from 400-700 nm (3,9). The radiation<br />
in this range, referred to as<br />
Photosynthetically Active Radiation<br />
(PAR), can be measured in energy units<br />
(watts m -2 ) or as Photosynthetic Photon<br />
Flux Density (PPFD), which has units of<br />
quanta (photons) per unit time per unit<br />
surface area. The units most commonly<br />
used are micromoles of quanta per second<br />
per square meter (µmol s -1 m -2 ).<br />
LI-190SA Quantum Sensor<br />
Plant scientists, horticulturists, ecologists,<br />
and other environmental scientists<br />
use the LI-190SA Quantum Sensor to accurately measure this<br />
variable.<br />
Accurate measurements are obtained under all natural and artificial<br />
<strong>li</strong>ghting conditions because of the computer-tailored spectral<br />
response of the LI-190SA. Colored glass filters are used to tailor<br />
the si<strong>li</strong>con photodiode response to the desired <strong>quantum</strong><br />
response (Figure 1). An interference filter provides a sharp cutoff<br />
at 700 nm, which is critical for measurements under vegetation<br />
where the ratio of infrared to visible <strong>li</strong>ght may be high. A<br />
small response in the infrared region can cause an appreciable<br />
measurement error. This <strong>sensor</strong>, developed from ear<strong>li</strong>er work<br />
(1), was pioneered by LI-COR and has become the standard for<br />
PPFD measurement in most photosynthesis-related studies.<br />
The LI-190SA is also used in oceanography, <strong>li</strong>mnology, and<br />
marine science as a reference <strong>sensor</strong> for comparison to underwater<br />
PAR measured by the LI-192SA Underwater Quantum<br />
Sensor.<br />
* Units currently used are moles, einsteins, photons and quanta (2, 4, 5).<br />
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<br />
quanta s -1 m -2 .<br />
PERCENT RELATIVE RESPONSE<br />
100<br />
80<br />
60<br />
40<br />
20<br />
0<br />
ULTRAVIOLET<br />
LI-COR<br />
QUANTUM SENSOR<br />
VIOLET<br />
BLUE<br />
IDEAL QUANTUM RESPONSE<br />
GREEN<br />
400 500 600 700<br />
YELLOW<br />
WAVELENGTH – NANOMETERS<br />
RED<br />
INFRARED<br />
LI-190SA SPECIFICATIONS<br />
Absolute Ca<strong>li</strong>bration: ± 5% traceable to the National Institute of<br />
Standards and Technology (NIST).<br />
Sensitivity: Typical 5µA per 1000 µmol s -1 m -2 .<br />
Linearity: Maximum deviation of 1% up to<br />
10,000 µmol s -1 m -2 .<br />
Stabi<strong>li</strong>ty: Typically < ± 2% change over a<br />
1 year period.<br />
Response Time: 10 µs.<br />
Tilt: No error induced from orientation.<br />
Operating Temperature: -40 to 65°C.<br />
Relative Humidity: 0 to 100%.<br />
Temperature Dependence: 0.15% per °C<br />
maximum.<br />
Cosine Correction: Cosine corrected up to<br />
80° angle of incidence.<br />
Azimuth: < ± 1% error over 360° at 45°<br />
elevation.<br />
Detector: High stabi<strong>li</strong>ty si<strong>li</strong>con photovoltaic detector (blue enhanced).<br />
Sensor Housing: Weatherproof anodized aluminum case with acry<strong>li</strong>c<br />
diffuser and stainless steel hardware.<br />
Size: 2.38 cm Dia. × 2.54 cm H (0.94” × 1.0”).<br />
Weight: 28 g (1 oz).<br />
Cable Length: 3.0 m (10 ft).<br />
ORDERING INFORMATION<br />
The LI-190SA Quantum Sensor cable terminates with a BNC connector<br />
that connects directly to the LI-250 Light Meter or LI-1400 DataLogger.<br />
The 2290 Mil<strong>li</strong>volt Adapter should be ordered if the LI-190SA will be<br />
used with a strip chart recorder or datalogger that measures mil<strong>li</strong>volts.<br />
The 2290 uses a 604 Ohm precision resistor to convert the LI-190SA<br />
output from microamps to mil<strong>li</strong>volts. The Quantum Sensor can also be<br />
ordered with bare leads (without the connector) and is designated<br />
LI-190SZ. Both are available with 50 foot cables, LI-190SA-50 or<br />
LI-190SZ-50. The 2003S Mounting and Leve<strong>li</strong>ng Fixture is recommended<br />
for each <strong>sensor</strong> unless other provisions for mounting are made.<br />
Other accessories are described on the Accessory Page.<br />
LI-190SA Quantum Sensor<br />
LI-190SZ Quantum Sensor<br />
LI-190SA-50 Quantum Sensor<br />
LI-190SZ-50 Quantum Sensor<br />
2290 Mil<strong>li</strong>volt Adapter<br />
2003S Mounting and Leve<strong>li</strong>ng Fixture<br />
2222SB-50 Extension Cable<br />
Figure 1. Typical spectral response of LI-COR Quantum Sensors<br />
vs. Wavelength and the Ideal Quantum Response (equal response<br />
2222SB-100 Extension Cable<br />
to all photons in the 400-700 nm waveband). 1
LI-191SA LINE QUANTUM SENSOR<br />
U.S. Patent 4,264,211.<br />
<strong>quantum</strong> response. Second, the single <strong>quantum</strong> <strong>sensor</strong> is much<br />
easier to keep in ca<strong>li</strong>bration than multiple (up to 80) individual<br />
gal<strong>li</strong>um arsenide detectors.<br />
LI-191SA SPECIFICATIONS<br />
Absolute Ca<strong>li</strong>bration: ± 10% traceable to NIST. The LI-191SA is<br />
ca<strong>li</strong>brated via transfer ca<strong>li</strong>bration from a LI-COR reference<br />
Quantum Sensor.<br />
The LI-191SA Line Quantum Sensor spatially<br />
averages PPFD over its one meter length.<br />
MEASURE PHOTOSYNTHETICALLY ACTIVE<br />
RADIATION IN PLANT CANOPIES<br />
During photosynthesis, plants use energy in the region of the<br />
electromagnetic spectrum from 400-700 nm (1, 2). The radiation<br />
in this range, referred to as Photosynthetically Active<br />
Radiation (PAR), can be measured in energy units (watts m -2 ) or<br />
as Photosynthetic Photon Flux Density (PPFD) which has units<br />
of quanta (photons) per unit time per unit surface area. The<br />
scaled units most commonly used are micromoles of quanta per<br />
second per square meter (µmol s -1 m -2 ).<br />
Measuring PAR within a plant canopy can be very difficult<br />
because of the non-uniformity of the <strong>li</strong>ght field. When PAR is<br />
measured with a small diameter <strong>quantum</strong> <strong>sensor</strong> such as the<br />
LI-190SA Quantum Sensor, intensity can vary 10-fold between<br />
sunflecks and shadows, requiring a large number of readings to<br />
get an accurate average. The LI-191SA Line <strong>quantum</strong> Sensor<br />
reduces the number of individual readings required because it<br />
effectively averages PPFD over its one meter length. One<br />
person can quickly make plant canopy PPFD measurements in<br />
many plots in a short period of time.<br />
Rather than using multiple detectors <strong>li</strong>nearly arranged over its<br />
one meter length, the LI-191SA uses a 1 meter long quartz rod<br />
under a diffuser to conduct <strong>li</strong>ght to a single high qua<strong>li</strong>ty <strong>quantum</strong><br />
<strong>sensor</strong> whose response is shown in Figure 1. There are two<br />
advantages of this design. First, the <strong>sensor</strong> has a very good<br />
<strong>quantum</strong> response un<strong>li</strong>ke <strong>sensor</strong>s using inexpensive gal<strong>li</strong>um<br />
arsenide detectors with only an approximation of the ideal<br />
Sensitivity: Typically 7 µA per 1000 µmol s -1 m -2 .<br />
Linearity: Maximum deviation of 1% up to 10,000 µmol s -1 m -2 .<br />
Stabi<strong>li</strong>ty: < ± 2% change over a 1 year period.<br />
Response Time: 10 µs.<br />
Temperature Dependence: ± 0.15% per °C maximum.<br />
Cosine Correction: Acry<strong>li</strong>c diffuser.<br />
Azimuth: < ± 2% error over 360° at 45° elevation.<br />
Sensitivity Variation over Length: ± 7% maximum using a 1” wide<br />
beam from an incandescent <strong>li</strong>ght source.<br />
Sensing Area: 1 meter L × 12.7 mm W (39.4” × 0.50”).<br />
Detector: High stabi<strong>li</strong>ty si<strong>li</strong>con photovoltaic detector (blue enhanced).<br />
Sensor Housing: Weatherproof anodized aluminum case with acry<strong>li</strong>c<br />
diffuser and stainless steel hardware.<br />
Size: 116 L × 2.54 W × 2.54 cm D (45.5” × 1.0” × 1.0”).<br />
Weight: 1.8 kg (4.0 lbs.).<br />
Cable Length: 3.1 m (10.0 ft.).<br />
ORDERING INFORMATION<br />
The LI-191SA Line Quantum Sensor comes with a bubble level,<br />
detachable 10 ft. cable and hardsided carrying case. The cable is<br />
terminated with a BNC connector and can be directly connected<br />
to a readout device such as the LI-250 Light Meter, LI-1400<br />
DataLogger or to the 2290 Mil<strong>li</strong>volt Adapter for connecting to<br />
readout devices requiring a mil<strong>li</strong>volt signal. Other accessories<br />
are described on the Accessory Page.<br />
LI-191SA Quantum Sensor<br />
2290 Mil<strong>li</strong>volt Adapter<br />
2222SB-50 Extension Cable<br />
2222SB-100 Extension Cable<br />
2
UNDERWATER PAR MEASUREMENT<br />
LI-192SA UNDERWATER QUANTUM SENSOR<br />
Underwater or Atmospheric PPFD Measurement<br />
Underwater or atmospheric Photosynthetic Photon Flux<br />
Density (PPFD) can be accurately measured using the<br />
LI-192SA Underwater Quantum Sensor. The LI-192SA is<br />
cosine corrected and features corrosion resistant, rugged<br />
construction for use in freshwater or saltwater and pressures<br />
up to 800 psi (5500 kPa, 560 meters depth).<br />
LI-192SA SPECIFICATIONS<br />
Absolute Ca<strong>li</strong>bration: ± 5% in air traceable to NIST.<br />
Sensitivity: Typically 4 µA per 1000 µmol s -1 m -2 in water.<br />
Linearity: Maximum deviation of 1% up to 10,000<br />
µmol s -1 m -2 .<br />
Stabi<strong>li</strong>ty: < ± 2% change over a 1 year period.<br />
Response Time: 10 µs.<br />
Temperature Dependence: ± 0.15% per °C maximum.<br />
Cosine Correction: Optimized for underwater and<br />
atmospheric use.<br />
Azimuth: < ± 1% error over 360° at 45° elevation.<br />
Detector: High stabi<strong>li</strong>ty si<strong>li</strong>con photovoltaic detector (blue<br />
enhanced).<br />
Sensor Housing: Corrosion resistant metal with acry<strong>li</strong>c diffuser<br />
for both saltwater and freshwater app<strong>li</strong>cations. Waterproof to<br />
withstand 800 psi (5500 kPa, 560 meters).<br />
Size: 3.18 cm Dia. × 4.62 cm H (1.25” × 1.81”).<br />
Weight: 227 g (8 oz.).<br />
Mounting: Three 6-32 holes are tapped into the base for use<br />
with the 2009S Lowering Frame or other mounting devices.<br />
Cable: Requires 2222UWB Underwater Cable.<br />
UNDERWATER PAR MEASUREMENT<br />
Accurate measurement of Photosynthetically<br />
Active Radiation (PAR, 400-700 nm) in<br />
aquatic environments is accomp<strong>li</strong>shed using<br />
either the LI-192SA Underwater Quantum<br />
Sensor or the LI-193SA Spherical Quantum<br />
Sensor. Limnologists, oceanographers and<br />
biologists conducting aquatic productivity<br />
studies and vertical profi<strong>li</strong>ng have used these<br />
<strong>sensor</strong>s extensively.<br />
For extremely turbid conditions, radiation<br />
levels with resolution to 0.01 µmol s -1 m -2<br />
can be measured with the LI-192SA or<br />
LI-193SA <strong>quantum</strong> <strong>sensor</strong>s and the<br />
LI-1400 DataLogger.<br />
Both the LI-192SA and the LI-193SA use<br />
computer-tailored filter glass to achieve the<br />
desired <strong>quantum</strong> response. Ca<strong>li</strong>bration is<br />
traceable to NIST.<br />
LI-193SA SPHERICAL QUANTUM SENSOR<br />
Underwater PAR From All Directions<br />
0.1 1.0 10 100 1000<br />
The LI-193SA Underwater Spherical Quantum Sensor gives an<br />
added dimension to underwater PAR measurements as it measures<br />
photon flux from all directions. This measurement is<br />
referred to as Photosynthetic Photon Flux Fluence Rate (PPFFR)<br />
or Quantum Scalar Irradiance. This is important, for example,<br />
when studying phytoplankton which uti<strong>li</strong>ze radiation from all<br />
directions for photosynthesis.<br />
The LI-193SA features a high sensitivity optical design and<br />
compact, rugged construction (3400 kPa, 350 meters depth).<br />
Depth (m)<br />
1<br />
2<br />
3<br />
4<br />
5<br />
6<br />
7<br />
8<br />
9<br />
10<br />
11<br />
-1 -2<br />
µmol s m<br />
Down Wel<strong>li</strong>ng<br />
Up Wel<strong>li</strong>ng<br />
LI-193SA SPECIFICATIONS<br />
Absolute Ca<strong>li</strong>bration: ± 5% in air traceable to NIST.<br />
Sensitivity: Typically 7 µA per 1000 µmol s -1 m -2 in water.<br />
Linearity: Maximum deviation of 1% up to 10,000<br />
µmol s -1 m -2 .<br />
Stabi<strong>li</strong>ty: < ± 2% change over a 1 year period.<br />
Response Time: 10 µS.<br />
Temperature Dependence: ± 0.15% per °C maximum.<br />
Angular Response: < ± 4% error up to ± 90° from normal axis<br />
(see Figure 3).<br />
Azimuth: < ± 3% error over 360° at 90° from normal axis.<br />
Detector: High stabi<strong>li</strong>ty si<strong>li</strong>con photovoltaic detector (blue<br />
enhanced).<br />
Clockwise: LI-190SA Quantum Sensor, LI-192SA Underwater Quantum<br />
Sensor, LI-193SA Spherical Quantum Sensor<br />
3
UNDERWATER PAR MEASUREMENT (CONT).<br />
Sensor Housing: Corrosion resistant metal for both saltwater<br />
and freshwater app<strong>li</strong>cations with an injection molded,<br />
impact resistant, acry<strong>li</strong>c diffuser. Units have been tested<br />
to 500 psi (3400 kPa, 350 meters) with no failures.<br />
Size<br />
Globe: 6.1 cm Dia. (2.4”).<br />
Housing: 3.18 cm Dia. (1.25”).<br />
Overall Height: 10.7 cm (4.2”).<br />
Weight: 142 g (0.31 lbs.).<br />
Mounting: Three 6-32 mounting holes are tapped into<br />
the base for use with the 2009S Lowering Frame or<br />
other mounting devices.<br />
Cable: Requires 2222UWB Underwater Cable.<br />
2009S LOWERING FRAME LOWERING<br />
Ø= 270°<br />
Ø= 0°<br />
8<br />
6<br />
4<br />
2<br />
Ø= 180°<br />
Figure 3.<br />
Typical Angular Response of the<br />
LI-193SA Spherical<br />
Quantum Sensor. The<br />
low response on the<br />
bottom of the <strong>sensor</strong><br />
Ø= 90° is due to <strong>li</strong>ght blockage<br />
by the detector<br />
housing. The error<br />
due to this low response<br />
is not significant in most<br />
cases because of the small<br />
portion of upwel<strong>li</strong>ng radiation<br />
compared to the total radiation.<br />
The 2009S Lowering Frame provides for the placement of two<br />
underwater cosine <strong>sensor</strong>s, one each for downwel<strong>li</strong>ng or<br />
upwel<strong>li</strong>ng radiation (shown below), or a single LI-193SA<br />
Spherical Quantum Sensor. The 2009S provides stabi<strong>li</strong>ty for<br />
proper orientation of the <strong>sensor</strong>(s), minimizes shading effects,<br />
and features a lower mounting ring for stabi<strong>li</strong>zing weight attachment<br />
if necessary.<br />
Construction: Anodized aluminum.<br />
Size: 51.4 L (20.3”) × 35.6 cm W (14.0”).<br />
Weight: 327 g (0.72 lbs.).<br />
2222UWB UNDERWATER CABLE<br />
This 2-wire shielded cable is used with underwater <strong>sensor</strong>s and<br />
has a waterproof connector on the <strong>sensor</strong> end. The other end of<br />
the cable is fitted with a BNC connector for attaching the cable<br />
directly to the readout instrument for type “SA” <strong>sensor</strong>s (also<br />
attaches to the calconnector of “SB” type <strong>sensor</strong>s). Standard<br />
cable lengths are 3, 10, 30, 50, 75, and 100 meters. Custom<br />
lengths over 100 meters can also be ordered.<br />
Underwater Sensors require 2222UWB Underwater Cable<br />
ORDERING INFORMATION<br />
LOWERING<br />
The Underwater Sensors can be purchased with several accessories.<br />
Please see Accessory Page for more details.<br />
2009S Lowering Frame<br />
LI-192SA Underwater Quantum Sensor<br />
LI-193SA Spherical Quantum Sensor<br />
2009S Lowering Frame<br />
2291 Mil<strong>li</strong>volt Adapter (1210 ohm)<br />
2222UWB-3 Underwater Cable, 3 meters<br />
2222UWB-10 Underwater Cable, 10 meters<br />
2222UWB-30 Underwater Cable, 30 meters<br />
2222UWB-50 Underwater Cable, 50 meters<br />
2222UWB-75 Underwater Cable, 75 meters<br />
2222UWB-100 Underwater Cable, 100 meters<br />
100L Lubricant<br />
4
®<br />
ENVIRONMENTAL DIVISION<br />
LI-200SA PYRANOMETER SENSOR<br />
TOTAL SOLAR RADIATION<br />
The LI-200SA Pyranometer is designed for field measurement of<br />
global solar radiation in agricultural, meteorological, and solar<br />
energy studies. In clear unobstructed day<strong>li</strong>ght conditions, the<br />
LI-COR pyranometer compares favorably with first class thermopile<br />
type pyranometers (5, 11), but is priced at a fraction of<br />
the cost.<br />
Patterned after the work of Kerr, Thurtell and Tanner (7), the<br />
LI-200SA features a si<strong>li</strong>con photovoltaic detector mounted in<br />
a fully cosine-corrected miniature head. Current output, which<br />
is directly proportional to solar radiation, is ca<strong>li</strong>brated against an<br />
Eppley Precision Spectral Pyranometer (PSP) under natural day<strong>li</strong>ght<br />
conditions in units of watts per square meter (W m -2 ).<br />
Under most conditions of natural day<strong>li</strong>ght, the error is
®<br />
LI-210SA PHOTOMETRIC SENSOR<br />
MEASURES ILLUMINANCE AS RELATED TO<br />
THE CIE STANDARD OBSERVER CURVE<br />
Sensor Housing: Weatherproof anodized aluminum case with<br />
acry<strong>li</strong>c diffuser and stainless steel hardware.<br />
Size: 2.38 Dia. × 2.54 cm H (0.94” × 1.0”).<br />
Weight: 28 g (1 oz.).<br />
Cable Length: 10 ft. standard.<br />
LI-210SA Photometric Sensor<br />
PHOTOMETRIC SENSORS<br />
Photometry refers to the measurement of visible radiation (<strong>li</strong>ght) with a <strong>sensor</strong><br />
having a spectral responsivity curve equal to the average human eye.<br />
This curve is known as the CIE Standard Observer Curve (photopic curve).<br />
Photometric <strong>sensor</strong>s are used to measure <strong>li</strong>ghting conditions where the eye<br />
is the primary receiver, such as illumination of work areas, interior <strong>li</strong>ghting,<br />
television screens, etc. Although photometric measurements have been<br />
used in the past in plant science, PPFD and irradiance are the preferred<br />
measurements.<br />
The LI-210SA Photometric Sensor uti<strong>li</strong>zes a filtered si<strong>li</strong>con photodiode<br />
to provide a spectral response that matches the CIE<br />
curve within ± 5% with most <strong>li</strong>ght sources. This photodiode and<br />
filter combination is placed within a fully cosine-corrected <strong>sensor</strong><br />
head to provide the proper response to radiation at various<br />
angles of incidence.<br />
100<br />
80<br />
60<br />
PHOTOMETRIC<br />
SENSOR<br />
CIE PHOTOPIC CURVE<br />
40<br />
Some of the app<strong>li</strong>cations for the LI-210SA Photometric Sensor<br />
include interior and industrial <strong>li</strong>ghting, outdoor illuminance,<br />
passive solar energy, architecture and <strong>li</strong>ghting models, illumination<br />
engineering, and biological sciences that require illuminance<br />
measurements. The LI-210SA is a research grade photometric<br />
<strong>sensor</strong> that is very reasonably priced.<br />
20<br />
0<br />
ULTRAVIOLET<br />
VIOLET<br />
BLUE<br />
GREEN<br />
YELLOW<br />
RED<br />
400 500 600 700<br />
WAVELENGTH – NANOMETERS<br />
INFRARED<br />
LI-210SA SPECIFICATION<br />
Absolute Ca<strong>li</strong>bration: ± 5% traceable to NIST.<br />
Sensitivity: Typically 30 µA per 100 klux.<br />
Linearity: Maximum deviation of 1% up to 100 klux.<br />
Stabi<strong>li</strong>ty: < ± 2% change over a 1 year period.<br />
Response Time: 10 µS.<br />
Temperature Dependence: ± 0.15% per °C maximum.<br />
Cosine Correction: Cosine corrected up to 80° angle<br />
of incidence.<br />
Azimuth: < ± 1% error over 360° at 45° elevation.<br />
Tilt: No error induced from orientation.<br />
Operating Temperature: -20 to 65 °C.<br />
Relative Humidity: 0 to 100%.<br />
Detector: High stabi<strong>li</strong>ty si<strong>li</strong>con photovoltaic<br />
detector (blue enhanced).<br />
ORDERING INFORMATION<br />
The LI-210SA Photometric Sensor cable terminates with a BNC<br />
connector that connects directly to the LI-250 Light Meter or<br />
LI-1400 DataLogger. The 2290 Mil<strong>li</strong>volt Adapter should be<br />
ordered if the LI-210SA will be used with a strip chart recorder<br />
or datalogger that measures mil<strong>li</strong>volts. The 2290 uses a 604<br />
Ohm precision resistor to convert the LI-210SA output from<br />
microamps to mil<strong>li</strong>volts. The Photometric Sensor can also be<br />
ordered with bare leads (without the connector) and is designated<br />
LI-210SZ. The 2003S Mounting and Leve<strong>li</strong>ng Fixture is recommended<br />
for each <strong>sensor</strong> unless other provisions for mounting<br />
are made. Other accessories are described on the Accessory<br />
Page.<br />
LI-210SA Photometric Sensor (with BNC connector)<br />
LI-210SZ Quantum Sensor (with bare leads)<br />
2003S Mounting and Leve<strong>li</strong>ng Fixture<br />
2222SB-50 Extension Cable (50 ft.)<br />
2222SB-100 Extension Cable (100 ft.)<br />
2290 Mil<strong>li</strong>volt Adapter<br />
6
SENSOR ACCESSORIES<br />
ACCESSORIES FOR<br />
TERRESTRIAL SENSORS<br />
2003S Mounting and Leve<strong>li</strong>ng Fixture<br />
The 2003S is for use with all LI-COR terrestrial type <strong>sensor</strong>s<br />
(2.38 cm Dia.). The base is anodized aluminum with stainless<br />
steel leve<strong>li</strong>ng screws and a weatherproof spirit level.<br />
Size: 7.6 cm Dia. (3.0”).<br />
Weight: 95 g (0.21 lbs).<br />
Type SZ Sensors<br />
Type SZ <strong>sensor</strong>s have the same specifications as the type SA<br />
<strong>sensor</strong>s except that they are terminated with bare wires for connection<br />
to the terminal blocks for the LI-1400 DataLogger or<br />
other current measuring devices. These <strong>sensor</strong>s can be converted<br />
to mil<strong>li</strong>volt output by connecting a resistor across the leads<br />
and measuring the voltage across the resistor.<br />
ACCESSORIES FOR<br />
UNDERWATER SENSORS<br />
2222UWB Underwater Cable<br />
This 2-wire shielded cable is used with underwater <strong>sensor</strong>s and<br />
has a waterproof connector on the <strong>sensor</strong> end. The other end of<br />
the cable is fitted with a BNC connector for attaching the cable<br />
directly to the readout instrument for type “SA” <strong>sensor</strong>s (also<br />
attaches to the calconnector of “SB” type <strong>sensor</strong>s). Standard<br />
cable lengths are 3, 10, 30, 50, 75 and 100 meters. Custom<br />
lengths over 100 meters can also be ordered.<br />
2222SB Extension Cable<br />
This cable is for use with LI-COR terrestrial type <strong>sensor</strong>s.<br />
Standard length is 15.2 m (50 ft) or 30.4 m (100 ft). Custom<br />
lengths up to 304 m (1000 ft) may be ordered. Cable lengths up<br />
to 1000 feet can be used with LI-COR readout instruments. For<br />
mV app<strong>li</strong>cations, consult LI-COR.<br />
2009S Lowering Frame<br />
The 2009S Lowering Frame provides for the placement of two<br />
underwater cosine <strong>sensor</strong>s, one each for downwel<strong>li</strong>ng or<br />
upwel<strong>li</strong>ng radiation (shown below), or a single LI-193SA<br />
Spherical Quantum Sensor. The 2009S provides stabi<strong>li</strong>ty for<br />
proper orientation of the <strong>sensor</strong>(s), minimizes shading effects,<br />
and features a lower mounting ring for stabi<strong>li</strong>zing weight<br />
attachment if necessary.<br />
Mil<strong>li</strong>volt Adapters<br />
Mil<strong>li</strong>volt adapters are used only for connecting <strong>sensor</strong>s to a<br />
user’s datalogger or stripchart recorder, not the LI-1400 or other<br />
LI-COR readout devices.<br />
Construction: Anodized<br />
aluminum.<br />
Size: 51.4 L (20.3”) x 35.6 cm<br />
W (14.0”).<br />
Weight: 327 g (0.72 lbs.).<br />
2290 Mil<strong>li</strong>volt Adapter<br />
For LI-190SA Quantum Sensor, LI-191SA Line Quantum<br />
Sensor, or LI-210SA Photometric Sensor (604 Ohm resistance).<br />
2220 Mil<strong>li</strong>volt Adapter<br />
For LI-200SA Pyranometer Sensor (147 Ohm resistance).<br />
2291 Mil<strong>li</strong>volt Adapter<br />
For LI-192SA Underwater Quantum Sensor or LI-193SA<br />
Spherical Quantum Sensor (1210 Ohm resistance).<br />
Underwater Sensors<br />
Require 2222UWB Underwater Cable. The 2009S Lowering<br />
Frame is an accessory.<br />
100L Lubricant<br />
Provides lubrication between the <strong>sensor</strong> and the underwater<br />
cable.<br />
7
LI-250 LIGHT METER<br />
Direct Digital Readout: Instantaneous <strong>sensor</strong> output<br />
or 15 second averages can be shown on the LI-250's<br />
display. Measurement units for any LI-COR <strong>sensor</strong><br />
(µmol, lux, klux, or W m -2 ) are also displayed.<br />
High Qua<strong>li</strong>ty Circuitry: The high qua<strong>li</strong>ty amp<strong>li</strong>fier in<br />
the LI-250 provides excellent long term stabi<strong>li</strong>ty and<br />
automatic zeroing. This high gain amp<strong>li</strong>fier gives very<br />
low input impedance to <strong>sensor</strong>s, resulting in excellent<br />
<strong>li</strong>nearity. Typical accuracy is 0.4% of reading at 25 °C.<br />
Automatic Range Selection: The LI-250 simp<strong>li</strong>fies<br />
operation by automatically selecting the range with<br />
the best accuracy and resolution for a given <strong>sensor</strong><br />
input signal. The wide dynamic range allows measurements<br />
in a wide variety of <strong>li</strong>ght environments.<br />
Hold Key: Pressing the HOLD key lets you retain<br />
the current reading on the display. Pressing the<br />
HOLD key again returns the LI-250 to measurement<br />
mode where the display is continuously updated.<br />
Average Key: 15 second averages can be collected<br />
and then held on the display by pressing the AVG key.<br />
Hand-held, Battery Operated: The LI-250's low<br />
power consumption gives you over 150 hours of<br />
operation from a single 9-volt transistor battery. To<br />
conserve battery <strong>li</strong>fe, the meter automatically shuts<br />
off after 20 minutes of inactivity.<br />
Sensor Ca<strong>li</strong>bration: Ca<strong>li</strong>bration multip<strong>li</strong>ers for LI-COR <strong>sensor</strong>s can be<br />
entered by simply pressing the CAL key, setting the display units (UNITS<br />
key), and then changing the <strong>sensor</strong> ca<strong>li</strong>bration multip<strong>li</strong>er with the up and<br />
down arrow keys. Two <strong>sensor</strong> multip<strong>li</strong>ers can be held in memory to aid in<br />
switching between <strong>sensor</strong>s.<br />
APPLICATIONS<br />
Like all LI-COR instruments, the LI-250 is designed for app<strong>li</strong>cations<br />
demanding performance, re<strong>li</strong>abi<strong>li</strong>ty and ruggedness.<br />
The LI-250 provides direct digital readout of LI-COR radiation<br />
<strong>sensor</strong>s.<br />
Photosynthetically Active Radiation (PAR)<br />
The LI-190SA Quantum Sensor is used by plant scientists, horticulturists,<br />
and other environmental scientists to measure<br />
Photosynthetic Photon Flux Density (PPFD - the preferred<br />
measurement of PAR) in natural sun<strong>li</strong>ght, under plant canopies,<br />
and in growth chambers and greenhouses.<br />
The LI-190SA is also used in oceanography, <strong>li</strong>mnology and<br />
marine sciences as a reference <strong>sensor</strong> for comparison to underwater<br />
PPFD measured by the LI-192SA Underwater Quantum<br />
Sensor. The LI-250 can hold ca<strong>li</strong>bration multip<strong>li</strong>ers in memory<br />
for both a surface and underwater <strong>sensor</strong>.<br />
Solar Irradiance<br />
Solar irradiance measurements for meteorological, hydrological<br />
and environmental research can be made using the LI-200SA<br />
Pyranometer Sensor. The LI-200SA measures global solar<br />
radiation (sun plus sky) and provides a typical accuracy of<br />
±5% under unobstructed day<strong>li</strong>ght conditions.<br />
SENSOR COMPATIBILITY<br />
Type "SA" <strong>sensor</strong>s (e.g. LI-190SA) are recommended for use<br />
with the LI-250. Older type "SB" <strong>sensor</strong>s (e.g. LI-190SB) can<br />
also be used by removing the ca<strong>li</strong>bration connector. Other types<br />
of older LI-COR <strong>sensor</strong>s can be made compatible by adding a<br />
BNC connector to the cable.<br />
Illuminance<br />
For <strong>li</strong>ghting studies or architectural mode<strong>li</strong>ng, the LI-250 and<br />
LI-210SA Photometric Sensor provide a direct readout of illuminance<br />
in lux. The LI-210SA measures visible radiation and has<br />
a spectral response curve equal to that for the average human<br />
eye. This curve is known as the CIE Standard Observer<br />
Curve and is matched by the LI-210SA to within 5% under most<br />
<strong>li</strong>ght sources.<br />
LI-250 Light Meter with LI-210SA Photometric Sensor<br />
and 2003S Mounting and Leve<strong>li</strong>ng Fixture.<br />
8
ACCESSORIES<br />
250-01 Carrying Case: The 250-01 has a tough nylon exterior<br />
and is padded to protect the LI-250 during transport. Internal<br />
compartments provide storage for the LI-250 and several <strong>sensor</strong>s.<br />
For field use, the 250-01 also lets you hang the meter on<br />
your belt.<br />
Size: 20 L × 9.5 W × 9 cm D.<br />
Operating Conditions: 0 to 55 °C, 0 to 95% RH<br />
(non-condensing).<br />
Storage Conditions: -55 to 60 °C, 0 to 95% RH<br />
(non-condensing).<br />
Size: 14 cm L × 7.7 cm W × 3.8 cm D (5.5" × 3" × 1.5").<br />
Weight: 0.26 kg (0.57 lbs).<br />
Warranty: 1 year parts and labor.<br />
LI-250 RANGE AND RESOLUTION<br />
Sensor Range Resolution<br />
250-01 Carrying Case.<br />
LI-250 SPECIFICATIONS<br />
Accuracy:<br />
25 ˚C: Typically ± 0.4% of reading ± 3 counts<br />
on the least significant digit displayed<br />
(all ranges).<br />
0 - 55 ˚C: Typically ± 0.6% of reading ± 3 counts<br />
on the least significant digit displayed<br />
(all ranges).<br />
Range Selection: Autoranging (3 ranges).<br />
Linearity: ± 0.05%.<br />
Sensors: Any LI-COR type "SA" or type "SB” <strong>sensor</strong> with<br />
BNC connector; Quantum, Pyranometer, or Photometric. Older<br />
LI-COR radiation <strong>sensor</strong>s, or those without any connector must<br />
have a BNC connector installed. Contact LI-COR.<br />
Sensor Ca<strong>li</strong>bration: Each <strong>sensor</strong> is supp<strong>li</strong>ed with a ca<strong>li</strong>bration<br />
multip<strong>li</strong>er. Ca<strong>li</strong>bration multip<strong>li</strong>ers for two <strong>sensor</strong>s can be stored<br />
in memory. Ca<strong>li</strong>bration multip<strong>li</strong>ers are entered from the keypad.<br />
Signal Averaging: Sensor output can be collected and displayed<br />
as a 15 second average (approximately 60 readings). Averages<br />
are retained on the display in HOLD mode.<br />
Display: 4 1/2 digit LCD display. Updated every 0.5 seconds<br />
in Instantaneous mode.<br />
Keypad: Sealed, 5-key tactile response keypad.<br />
Battery Life: 150 hours typical with continuous operation.<br />
Power Requirement: One 9V Eveready Alka<strong>li</strong>ne #522 or<br />
equivalent (LI-COR part number 216).<br />
Low Battery Detection: Low battery indicator displayed with<br />
approximately 20 hours battery <strong>li</strong>fe remaining.<br />
Quantum 199 µmol s -1 m -2 0.01 µmol s -1 m -2<br />
1999 0.1<br />
19999 1<br />
Radiometric 19 W m -2 0.001 W m -2<br />
199 0.01<br />
1999 0.1<br />
Photometric 1999 lux 0.1 lux<br />
19999 lux 1<br />
199 klux 0.01 klux<br />
ORDERING INFORMATION<br />
LI-250 Light Meter<br />
Battery included. Order <strong>sensor</strong>s separately.<br />
Options<br />
250-01 Carrying Case<br />
216 Replacement Battery. 9 volt transistor type.<br />
Requires 1 for replacement.<br />
Sensors<br />
LI-190SA Quantum Sensor<br />
LI-200SA Pyranometer Sensor<br />
LI-210SA Photometric Sensor<br />
LI-191SA Line Quantum Sensor<br />
2003S Mounting and Leve<strong>li</strong>ng Fixture<br />
2222SB Extension Cable (50 ft.)<br />
2222SB-100 Extension Cable (100 ft.)<br />
Underwater Sensors<br />
LI-192SA Underwater Quantum Sensor<br />
LI-193SA Spherical Quantum Sensor<br />
2222UWB Underwater Cable. Standard lengths<br />
range from 3 to 100 meters. Custom lengths are<br />
available.<br />
2009S Lowering Frame<br />
9
LI-1400 DATALOGGER<br />
High accuracy with LI-COR <strong>li</strong>ght <strong>sensor</strong>s. Three<br />
external <strong>li</strong>ght <strong>sensor</strong> connectors for fast setup.<br />
Two additional current channels, four voltage<br />
channels, one pulse counting channel and several<br />
regulated and unregulated voltage supp<strong>li</strong>es.<br />
96K Bytes RAM for data storage.<br />
Ergonomic, <strong>li</strong>ght weight for hand-held operation as<br />
a meter with instantaneous or averaged readout.<br />
Nine math channels for direct readout of saturation<br />
vapor pressure, dew point temperature, vertical <strong>li</strong>ght<br />
attenuation coefficients (underwater), and more.<br />
Two <strong>li</strong>ne LCD display shows <strong>sensor</strong> instantaneous<br />
or logged <strong>sensor</strong> outputs, stored data,<br />
battery voltage and more.<br />
Autoranging electronics with low power consumption.<br />
Easy to use internal software with setup macro<br />
<strong>li</strong>braries to simp<strong>li</strong>fy <strong>sensor</strong> configuration.<br />
RS-232C data output to PC-compatible or Macintosh<br />
computers in "spreadsheet-ready" format.<br />
Alphanumeric keypad speeds entry of remarks for<br />
data identification.<br />
SIMPLIFIED DATA LOGGING<br />
Operating the LI-1400 is easy. All functions are selectable from<br />
short <strong>li</strong>sts using cursor keys. Commonly used functions <strong>li</strong>ke<br />
printing and memory management are assigned to a function <strong>li</strong>st<br />
on a dedicated key for quick access. Other important functions<br />
<strong>li</strong>ke instrument setup and data display are also assigned to dedicated<br />
keys.<br />
FAST SETUP<br />
Channel setup is simp<strong>li</strong>fied by the use of log routines<br />
that e<strong>li</strong>minate entering repetitive information. The<br />
LI-1400's log routines allow you to enter the logging<br />
period, start/stop times and other information in one<br />
place, and then apply that log routine to as many<br />
channels as required.<br />
Each channel can be individually configured to<br />
collect data for logging periods as short as 1 second<br />
or as long as 24 hours. Samp<strong>li</strong>ng intervals within<br />
each logging period are selectable from 1 second to one hour.<br />
For each logging period, data can be integrated or averaged.<br />
Alternatively, an instantaneous point reading can be taken at<br />
the end of each period. The maximum and minimum readings<br />
within the logging period and the time of their occurrence can<br />
also be stored.<br />
MATH FUNCTIONS<br />
Channel setup includes choosing from a <strong>li</strong>st of math functions<br />
that can be app<strong>li</strong>ed to <strong>sensor</strong> inputs. In addition to <strong>sensor</strong> input<br />
sca<strong>li</strong>ng or <strong>li</strong>nearization, several powerful calculations can be performed<br />
using math functions:<br />
Math Operators (+, –, ×, ÷): Used to combine one input with<br />
another through channel addition, subtraction, etc. For example,<br />
math operators can determine the ratio of two similar <strong>sensor</strong>s in<br />
different environmental conditions, <strong>li</strong>ke an LI-190SA Quantum<br />
Sensor at the water's surface and an LI-192SA Quantum Sensor<br />
underwater.<br />
Steinhart-Hart Function: Calculates temperature from thermistor<br />
type temperature <strong>sensor</strong>s such as<br />
LI-COR air and soil temperature <strong>sensor</strong>s.<br />
Saturation Vapor Pressure: Calculated<br />
when temperature is input from an air temperature<br />
<strong>sensor</strong>.<br />
Dew Point Temperature: Calculates the<br />
dew point temperature using signals from<br />
the 1400-104 Relative Humidity and Air<br />
Temperature Sensor (or equivalent).<br />
Natural Log: Multip<strong>li</strong>es a constant by the<br />
natural log of a channel input. When used<br />
in conjunction with math operators, this function can be used to<br />
calculate the vertical <strong>li</strong>ght attenuation coefficient between two<br />
underwater <strong>quantum</strong> <strong>sensor</strong>s submerged at different depths.<br />
Polynomial: A fifth order polynomial is provided for <strong>sensor</strong><br />
<strong>li</strong>nearization.<br />
Math Libraries: Five math <strong>li</strong>braries are available to store values<br />
for any of the above math functions. For example, if the same<br />
<strong>li</strong>nearization polynomial is to be used for several <strong>sensor</strong> inputs,<br />
storing the polynomial in one of the math <strong>li</strong>braries e<strong>li</strong>minates<br />
re-entering the polynomial for every <strong>sensor</strong>.<br />
10
MATH CHANNELS<br />
The logging and calculation capabi<strong>li</strong>ties of the LI-1400 are<br />
extended by nine math channels. Math channels let you perform<br />
additional logging or math routines using any other current,<br />
voltage or math channel. For example, if you are<br />
logging total daily solar radiation from an LI-200SA<br />
Pyranometer <strong>sensor</strong> connected to current channel #1,<br />
you can also log hourly integrations or averages from<br />
the same <strong>sensor</strong> by adding the channel #1 input to a<br />
math channel and then setting the log routine on the<br />
math channel for hourly integrations. Any of the<br />
math operators or math functions described above can<br />
be used in the math channels as well.<br />
CIRCUITRY<br />
The LI-1400 uses an autoranging, trans-impedance,<br />
chopper stabi<strong>li</strong>zed amp<strong>li</strong>fier for high resolution (8<br />
picoamp), high accuracy measurements of LI-COR radiation<br />
<strong>sensor</strong>s and other <strong>sensor</strong>s with a current output. The high gain<br />
amp<strong>li</strong>fier and unique circuit topology gives an extremely low<br />
input impedance (< 0.03 ohm) to current <strong>sensor</strong>s, resulting in<br />
excellent <strong>li</strong>nearity. Measurement accuracy is enhanced by performing<br />
an auto zero and span before every reading (or once per<br />
minute with 1 second samp<strong>li</strong>ng rate) using a high precision, low<br />
drift reference. A precision sigma-delta analog-to-digital converter<br />
allows high speed, low noise measurements to be made.<br />
Highly accurate, single-ended voltage measurements are<br />
achieved using a precision instrumentation amp<strong>li</strong>fier. Voltage<br />
output transducers with low or high output impedance are accurately<br />
measured because of very high amp<strong>li</strong>fier input impedance.<br />
CURRENT CHANNELS<br />
The LI-1400 has unrivaled resolution for LI-COR radiation <strong>sensor</strong>s.<br />
Current resolution down to 8 picoamps is available<br />
through three sealed BNC connectors and two additional channels<br />
on the 1400-301 Terminal Block.<br />
The three BNC current channels are designed for type "SA"<br />
radiation <strong>sensor</strong>s <strong>li</strong>ke LI-COR's LI-190SA Quantum Sensor,<br />
LI-200SA Pyranometer Sensor or LI-210SA Photometric Sensor.<br />
LI-COR Type "SZ" radiation <strong>sensor</strong>s, with bare wire leads, are<br />
recommended for use with the terminal block.<br />
For other <strong>sensor</strong>s, the LI-1400 can measure current up to ± 250<br />
microamps with very high resolution.<br />
VOLTAGE CHANNELS<br />
Four single-ended voltage channels (± 2.5 VDC) provide high<br />
input impedance for measuring a wide range of <strong>sensor</strong>s,<br />
including LI-COR temperature <strong>sensor</strong>s and humidity <strong>sensor</strong>s.<br />
Voltage measurements require the 1400-301 Terminal Block.<br />
PULSE COUNTING<br />
The LI-1400 has one pulse counting channel for logging total<br />
rainfall from LI-COR's 1400-106 Tipping Bucket Rain Gauge<br />
(or equivalent). The counter channel can be accessed through<br />
the 1400-301 Terminal Block.<br />
ENVIRONMENTAL OPERATION<br />
The LI-1400's rugged, splash resistant case<br />
protects it from exposure to the environment.<br />
Operating temperatures are from<br />
-25 to 55 °C. For operation at remote sites,<br />
the 1400-201 Vented Instrument Enclosure<br />
is recommended to protect <strong>sensor</strong> connections<br />
from rain water and to shade the<br />
LI-1400 from direct sun<strong>li</strong>ght.<br />
The LI-1400 is powered by four "AA"<br />
batteries which provide over 60 hours of<br />
hand-held, instantaneous operation as a<br />
meter. For remote logging app<strong>li</strong>cations, the<br />
1400-402 external "D" cell battery pack<br />
provides over a year of data logging operation from six batteries.<br />
To ensure continuous operation, a low battery warning is<br />
displayed when the batteries are depleted; a <strong>li</strong>thium back-up<br />
battery protects the memory while changing batteries.<br />
While logging data, the LI-1400 conserves battery <strong>li</strong>fe by<br />
operating fully powered only when it must sample a given<br />
channel. After samp<strong>li</strong>ng channels and storing data (if necessary),<br />
the LI-1400 automatically returns to a state of low power<br />
consumption.<br />
DATA STORAGE<br />
The LI-1400 has 96K bytes RAM for data storage. The storage<br />
capacity is dependent on the software configuration.<br />
DATA OUTPUT<br />
Windows 95 ® communication software is included for:<br />
• Rapid binary data transfer<br />
• ASCII data transfer<br />
• Datalogger configuration changes<br />
from the computer.<br />
Stored data can also be transferred to PC-compatible or<br />
Macintosh computers using any terminal program. The LI-1400<br />
data is formatted for easy import into widely used spreadsheet<br />
and database software.<br />
Data can be automatically output via the RS-232 port after<br />
every logging period. When using short logging periods, this<br />
feature allows data capture by a computer with large storage<br />
capacity.<br />
HAND-HELD OPERATION<br />
As an autoranging meter, the LI-1400 provides direct readout for<br />
up to three LI-COR radiation <strong>sensor</strong>s without requiring a<br />
terminal input block.<br />
The output of a given <strong>sensor</strong> can be viewed on the LCD display<br />
11
or stored in memory by simply pressing<br />
the ENTER key on the keypad (data for<br />
all operative channels are stored, along<br />
with the time at which the data were<br />
logged).<br />
Radiation measurements in water or under changing cloud cover<br />
often require an averaged reading of <strong>sensor</strong> output to obtain the<br />
best results. The LI-1400 can display a continuous running<br />
average for each <strong>sensor</strong>. The length of the average is user selectable<br />
for each channel. Instantaneous or averaged values for any<br />
<strong>sensor</strong> can also be displayed while the LI-1400 is logging data.<br />
1400-102 Air Temperature Sensor: Same as 1400-101 except<br />
cable length is 2 ft. for mounting in 1400-201 Vented Instrument<br />
Enclosure.<br />
1400-104 Relative Humidity and Air Temperature Sensor<br />
(Vaisala): 9 ft. cable. Can be mounted in 1400-201 Vented<br />
Instrument Enclosure.<br />
1400-106 Tipping Bucket Rain Gauge: Ca<strong>li</strong>brated in mil<strong>li</strong>meters.<br />
Tipping bucket mechanism activates a sealed reed switch<br />
that produces a contact closure for each 1 mm of rainfall. 50<br />
foot cable.<br />
ORDERING INFORMATION<br />
LI-1400 DataLogger: Includes 4 "AA" batteries and Windows<br />
95 ® communication software. Sensors not included.<br />
1400-301 Standard Terminal Block: Allows connection to two<br />
additional current channels, 4 voltage channels, 1 pulse counting<br />
channel, two unregulated voltage supp<strong>li</strong>es, and two regulated +5<br />
volt DC supp<strong>li</strong>es for LI-COR temperature <strong>sensor</strong> and other<br />
<strong>sensor</strong>s requiring a constant voltage input.<br />
1400-401 AC Adapter: Requires 120 VAC, 60 Hz. Used for<br />
app<strong>li</strong>cations where continuous operation is required.<br />
1400-402 External Alka<strong>li</strong>ne Battery Pack: Holds 6 "D" cell<br />
batteries for remote logging app<strong>li</strong>cations. The 1400-402 has<br />
provisions for mounting in the 1400-201 Vented Instrument<br />
Enclosure.<br />
1400-320 Storage Case: Foam-<strong>li</strong>ned<br />
plastic case for LI-1400, <strong>sensor</strong>s, and<br />
accessories.<br />
1400-201 Vented Instrument Enclosure:<br />
Wooden enclosure to <strong>li</strong>mit exposure of<br />
1400-301<br />
LI-1400 and <strong>sensor</strong> connections.<br />
Dimensions: 19L × 19W × 56 cm H (7.5”<br />
× 7.5” × 22”). Weight: 4.8 kg (10.5 lb).<br />
Includes one 1400-310 Mounting Bracket.<br />
1400-310 Mounting Bracket: For mounting the LI-1400 in<br />
third-party instrument enclosures, or any other vertical or<br />
inc<strong>li</strong>ned surface.<br />
SENSORS<br />
Quantum Sensors: LI-190SA Quantum Sensor, LI-190SZ<br />
Quantum Sensor, LI-191SA Line Quantum Sensor, LI-192SA<br />
Underwater Quantum Sensor, LI-193SA Spherical Quantum<br />
Sensor.<br />
Pyranometer Sensors: LI-200SA, LI-200SZ.<br />
Photometric Sensors: LI-210SA, LI-210SZ.<br />
1400-103 Soil Temperature Sensor: 20 foot cable.<br />
Accuracy: ± 0.5 °C.<br />
1400-101 Air Temperature Sensor: 20 foot cable.<br />
Accuracy: ± 0.5 °C.<br />
1400-104 Relative Humidity/Temperature Sensor,<br />
1400-101 Air Temperature Sensor, and 1400-103 Soil<br />
Temperature Sensor (left to right).<br />
DATA OUTPUT ACCESSORIES<br />
1400-550 RS-232C Cable: For connection to PC-compatible<br />
computers with a 9-pin RS-232C communication port (DTE-to-<br />
DTE).<br />
SPECIFICATIONS<br />
Current Inputs: Five channels; three through external sealed<br />
BNC connectors, and two through the 1400-301 Standard<br />
Terminal Block.<br />
Voltage Inputs: Four high impedance (>500M ohm) singleended<br />
channels accessed through the 1400-301 Terminal Block.<br />
Pulse Counting Input: One pulse counting channel. Switch<br />
closure for tipping bucket rain gauge (1 Hz maximum).<br />
Math Channels: 9 math channels. Math channels combine<br />
results of two channels with addition, subtraction, multip<strong>li</strong>cation<br />
and division operators. Other math channel functions include<br />
fifth order polynomial, Steinhart-Hart function for thermistors,<br />
natural log, saturation vapor pressure, and dew point. Five math<br />
<strong>li</strong>braries are available to store commonly used functions.<br />
Analog-to-Digital Converter:<br />
Resolution: 16 bit (1 part in 65,536).<br />
Scanning Speed: 10 channels per second.<br />
Voltage Accuracy: < 0.1% of full scale reading<br />
(25 °C). ± 0.15% (0 to 55 °C).<br />
Current Accuracy: ± 0.2% of full scale reading<br />
(25 °C). ± 0.4% (0 to 55 °C).<br />
12
Temperature Coefficient: ± 0.01% of reading per °C.<br />
Linearity: 0.07%.<br />
Frequency Rejection: >90 dB at 50 or 60 Hz (software<br />
selectable).<br />
Input Noise (25 °C)<br />
Typical<br />
Maximum<br />
Voltage ± 76 µV ± 152 µV<br />
Current ± 7.6 picoamps ± 30.4 picoamps<br />
Voltage Range (Channels V1-V4):<br />
Voltage Range<br />
Resolution:<br />
± 2.5 volts 76 microvolts<br />
Current Range Selection:<br />
Autoranging.<br />
Current Ranges<br />
Resolution<br />
1 ± 250 nanoamps 7.6 picoamps<br />
2 ± 2.5 microamps 76 picoamps<br />
3 ± 25 microamps 760 picoamps<br />
4 ± 250 microamps 7.6 nanoamps<br />
Typical Resolution with LI-COR radiation <strong>sensor</strong>s (Range 1)<br />
LI-190SA .0015 µmole sec -1 m -2<br />
LI-200SA .0001 watts m -2<br />
LI-210SA .025 lux<br />
Current Channel Input Impedance: Typically < 0.03 ohm for<br />
ranges 1, 2, or 3; < 0.3 ohm for range 4.<br />
Voltage Channel Input Impedance: >500M ohm on voltage<br />
channels V1 through V4. 100K ohm for current channels I4 and<br />
I5, when configured for voltage input.<br />
D.C. Voltage Excitation: Two regulated: + 5.0 V ± 0.2% at 3<br />
mA; Two unregulated: 9.5V ±10% or higher at 6mA. With external<br />
14V input, unregulated output is ≈13.4V.<br />
Logging Periods: Seconds: 1, 5, 15, 30. Minutes: 1, 5, 15, 30.<br />
Hours: 1, 3, 6, 12, 24.<br />
Samp<strong>li</strong>ng Interval: Seconds: 1, 5, 15, 30. Minutes: 1, 5, 15,<br />
30, 60.<br />
Short Term Averaging: Selectable at 1, 5, 15, or 30 seconds.<br />
While averaging, the oldest point is dropped when the newest<br />
point is added. Averaged readings reduce instrument noise by<br />
approximately the square root of the number of samples.<br />
Keyboard: Sealed, 24 key tactile response keypad.<br />
Display: Two <strong>li</strong>ne, 16 character alphanumeric LCD. Updated<br />
once per second. Temperature compensated readabi<strong>li</strong>ty from -15<br />
to 55 °C.<br />
Real Time Clock: Year, month, day, hour, minute, seconds.<br />
Accuracy: ± 3 minutes per month (25 °C).<br />
Internal Memory: 96K bytes available for data storage.<br />
Program Memory: Stored in Flash memory for easy upgrades<br />
via the RS-232 port.<br />
Communications: RS-232C, hardwired Data Terminal<br />
Equipment (DTE) through 9-pin port. Baud rates are software<br />
selectable at 300,1200, 2400, 4800 and 9600. Communication is<br />
bi-directional.<br />
Battery Requirements: Four Alka<strong>li</strong>ne "AA" batteries in sealed<br />
battery compartment.<br />
Back-up Battery: Internal <strong>li</strong>thium battery maintains memory<br />
up to seven years.<br />
Battery Voltage: Automatic low battery instrument shut-off.<br />
Remaining power after shut-off maintains data stored in memory.<br />
Low battery warning displayed before automatic shut-off.<br />
Power management software also shuts off the instrument after<br />
15 minutes of inactivity.<br />
Battery Capacity with "AA" Batteries: 60 hours continuous<br />
operation.<br />
External DC Power: 7 - 16 VDC.<br />
Case: ABS plastic case for splash resistant operation and protection<br />
from wind blown dust. Equivalent to an IP54 level.<br />
Operating Conditions: -25 to 55 °C; 0 to 95% RH, non-condensing.<br />
Storage Conditions: -30 to 60 °C; 0 to 95% RH,<br />
non-condensing.<br />
Size: 22L × 13W × 4.3 cm D (8.6 × 5.1 × 1.7”). 9.3 cm (3.7")<br />
width of the lower case allows easy hand-held operation.<br />
Weight: 0.7 kg (1.5 lb).<br />
13
LI-1401 AGRO-METEOROLOGICAL STATION<br />
The LI-1401 Agro-Meteorological Station is a complete meteorological<br />
data logging system designed for simple operation<br />
and easy setup.<br />
The LI-1401 includes the LI-1400, a 10-channel data logger,<br />
and all <strong>sensor</strong>s needed to collect total daily solar irradiance,<br />
precipitation, air temperature, soil temperature, relative<br />
humidity, wind speed, and wind direction.<br />
A dedicated software configuration provides for simple setup.<br />
Simply choose the desired samp<strong>li</strong>ng and logging periods, and<br />
you're ready to collect data. Data stored in memory can be<br />
viewed on the LCD display, or output to a computer. Data<br />
can be offloaded in the field without interrupting the logging<br />
process.<br />
The heavy duty, self-guying tripod makes site selection simple,<br />
and allows easy transport to multiple locations for crop<br />
mode<strong>li</strong>ng, plant growth studies, soil characterization, irrigation<br />
schedu<strong>li</strong>ng, and crop management app<strong>li</strong>cations.<br />
INCLUDES THE FOLLOWING:<br />
LI-1400 DataLogger<br />
1400-301 Terminal Block<br />
LI-200SA Pyranometer<br />
1400-103 Soil Temperature Sensor<br />
1400-104 Air Temperature/Relative Humidity Sensor<br />
(Vaisala)<br />
1400-105 Wind Direction/Speed Sensors (RM Young)<br />
1400-106 Tipping Bucket Raingauge<br />
1400-204 Tripod (self guying design)<br />
1400-205 Mounting Bar<br />
1400-202 Gill Radiation Shield<br />
1400-203 Sealed Instrument Enclosure<br />
1400-402 External Alka<strong>li</strong>ne Battery Pack<br />
1400-550 RS-232 Communications Cable (9-pin to 9-pin)<br />
14
LI-1405 BASIC WEATHER STATION<br />
The LI-1405 Basic Weather Station is an economical weather<br />
station designed to measure the basic meteorological parameters<br />
required for agricultural research. The vented instrument<br />
enclosure mounts easily to a pole or post and not only<br />
provides protection for the data logger and battery pack, but<br />
serves as a mounting platform for the pyranometer and the air<br />
temperature <strong>sensor</strong>. Data are easily downloaded in spreadsheet-ready<br />
format to a PC with the included software.<br />
An economical alternative to the LI-1401, the LI-1405 Basic<br />
Weather Station contains the same 10-channel datalogger<br />
(LI-1400), with <strong>sensor</strong>s to measure solar radiation, air and soil<br />
temperature, and rainfall. These measurements provide a basic<br />
dataset of environmental parameters for many agricultural<br />
research app<strong>li</strong>cations.<br />
INCLUDES THE FOLLOWING:<br />
LI-1400 DataLogger<br />
1400-301 Terminal Block<br />
LI-200SA Pyranometer<br />
1400-102 Air Temperature Sensor<br />
1400-103 Soil Temperature Sensor<br />
1400-106 Tipping Bucket Raingauge<br />
1400-201 Vented Instrument Enclosure<br />
1400-402 External Alka<strong>li</strong>ne Battery Pack<br />
2003S Mounting and Leve<strong>li</strong>ng Fixture<br />
1400-550 RS-232 Communications Cable (9-pin to 9-pin)<br />
Spare input channels allow you to add other LI-COR<br />
<strong>sensor</strong>s, or <strong>sensor</strong>s from other manufacturers to create your<br />
own customized system.<br />
15
LI-1401 & LI-1405 SPECIFICATIONS:<br />
LI-1400 DataLogger<br />
Current Inputs: Five channels; three<br />
through external sealed BNC connectors,<br />
and two through the 1400-301<br />
Standard Terminal Block.<br />
Voltage Inputs: Four high impedance<br />
(>500 Megohm) single-ended channels<br />
accessed through the 1400-301<br />
Terminal Block.<br />
Pulse Counting Input: One pulse<br />
counting channel. Switch closure for<br />
tipping bucket rain gauge.<br />
Logging Periods: Seconds: 1, 5, 15, 30. Minutes: 1, 5, 15,<br />
30. Hours: 1, 3, 6, 12, 24.<br />
Samp<strong>li</strong>ng Interval: Seconds: 1, 5, 15, 30.<br />
Minutes: 1, 5, 15, 30, 60.<br />
Keyboard: Sealed, 24 key tactile response keypad.<br />
Display: Two <strong>li</strong>ne, 16 character alphanumeric LCD. Updated<br />
once per second. Temperature compensated readabi<strong>li</strong>ty<br />
from -15 to 55°C.<br />
Internal Memory: 96K bytes available for data storage.<br />
Program Memory: Stored in Flash memory for easy upgrades<br />
via the RS-232C port.<br />
Communications: RS-232C, hardwired Data Terminal<br />
Equipment (DTE) through 9-pin port. Baud rates are software<br />
selectable at 300, 1200, 2400, 4800 and 9600.<br />
Communication is bi-directional.<br />
External DC Power: 7 - 16 VDC.<br />
Operating Conditions: -25 to 55 °C; 0 to 95% RH,<br />
non-condensing.<br />
1400-104 Air Temperature/ Relative Humidity Sensor<br />
(LI-1401 only)<br />
Air Temperature<br />
Type: Platinum RTD<br />
Accuracy: ± 0.8°C<br />
Output: 0-1V = -40 to +60°C<br />
Relative Humidity<br />
Type: Capacitance<br />
Accuracy: ±3% (10-90% RH)<br />
Output: 0-1V = 0 to 100% RH<br />
1400-105 Wind Direction/Speed Sensors (LI-1401 only)<br />
Wind Direction<br />
Type: Vane<br />
Range: 0 to 360 degrees<br />
Accuracy: ±5 degrees<br />
Threshold: 2.9 mph<br />
Output: 0-1V = 0 to 360 degrees<br />
Wind Speed<br />
Type: 3 cup<br />
Range: 0 to 112 mph<br />
Accuracy: ±1.1 mph<br />
Threshold: 2.5 mph<br />
Output: 0-1V = 0 to 100 mph<br />
1400-106 Tipping Bucket Raingauge<br />
Type: Tipping bucket<br />
Output: 1 pulse mm -1 16<br />
LI-200SA Pyranometer<br />
Type: High stabi<strong>li</strong>ty si<strong>li</strong>con photovoltaic detector<br />
Range: 0-1500 watts m -2<br />
Output: Typically 90 µA (1000 w -1 m -2 )<br />
Error: Typically ±5%<br />
1400-102 Air Temperature Sensor (LI-1405 only)<br />
1400-103 Soil Temperature Sensor<br />
Type: Thermistor<br />
Range: -40 to +50°C<br />
Accuracy: ±0.5°C<br />
Output: Temperature proportional to microamp current<br />
using 5th order polynomial
OPTICAL RADIATION CALIBRATOR<br />
• Spectral irradiance, irradiance, illuminance<br />
and photon flux ca<strong>li</strong>brations.<br />
• For ca<strong>li</strong>bration of LI-COR Spectroradiometers,<br />
<strong>quantum</strong> <strong>sensor</strong>s and photometric <strong>sensor</strong>s.<br />
• Simple operation.<br />
• E<strong>li</strong>minates complex optical a<strong>li</strong>gnments and<br />
expensive laboratory ca<strong>li</strong>bration equipment.<br />
The 1800-02 is a self-contained optical radiation ca<strong>li</strong>brator for<br />
on-site spectral irradiance, irradiance, photon flux, or<br />
illuminance ca<strong>li</strong>brations in the 300-1100 nm wavelength range.<br />
The 1800-02 integrates a quartz tungsten halogen lamp and a<br />
highly regulated power supply into a portable package that acts<br />
as an optical bench and darkroom. The 1800-02 can be<br />
operated under normal <strong>li</strong>ghting conditions and requires no<br />
special faci<strong>li</strong>ties.<br />
THE LAMP<br />
The 1800-02 uti<strong>li</strong>zes a 200 Watt quartz tungsten halogen lamp<br />
operated at an approximate color temperature of 3150° Kelvin.<br />
The tungsten halogen lamp provides the best available spectral<br />
distribution for ca<strong>li</strong>brations in the 300-1100 nm wavelength<br />
range. Lamp ca<strong>li</strong>brations are determined by using a temperature<br />
controlled spectroradiometer to compare readings over the 300-<br />
1100 nm wavelength range taken from the 1800-02 and the<br />
working standard ca<strong>li</strong>bration lamp used in LI-COR's laboratory<br />
ca<strong>li</strong>bration system. LI-COR's working standard quartz halogen<br />
lamps have been ca<strong>li</strong>brated against reference standard lamps<br />
traceable to NIST. Ca<strong>li</strong>bration accuracy of the 1800-02 is<br />
± 4.0% from 300-1100 nm.<br />
POWER SUPPLY<br />
The1800-02 has a highly regulated power supply which maintains<br />
constant power to the lamp by regulating both current and<br />
voltage. Regulating both current and voltage results in added<br />
lamp stabi<strong>li</strong>ty.<br />
When the 1800-02 is turned on, the lamp is powered up slowly<br />
to prevent filament shock and a ready <strong>li</strong>ght indicates when the<br />
lamp is within normal operating conditions. The lamp is protected<br />
by a built-in over current protector which shuts off the<br />
power supply in case of malfunction. Automatic shutoff also<br />
occurs if the <strong>li</strong>ne voltage falls too low to maintain accurate regulation,<br />
thereby preventing false ca<strong>li</strong>bration data. External jacks<br />
for monitoring lamp current and voltage through a precision ca<strong>li</strong>brated<br />
shunt are provided to allow user verification of lamp stabi<strong>li</strong>ty.<br />
OPERATION<br />
Operation of the 1800-02 is a simple 3 step process.<br />
1) Turn the 1800-02 on and allow 5 minutes after the<br />
"ready” <strong>li</strong>ght comes on for the lamp to reach complete<br />
thermal stabi<strong>li</strong>ty.<br />
2) Install the <strong>sensor</strong> or spectroradiometer in the instrument<br />
port using the appropriate mounting fixture (provided).<br />
3) Read the <strong>sensor</strong> (or scan the lamp with a<br />
spectroradiometer) and determine the ca<strong>li</strong>bration<br />
constant from the lamp ca<strong>li</strong>bration data.<br />
Sensor ca<strong>li</strong>brations are performed using the <strong>sensor</strong> mounting fixture<br />
which holds the <strong>sensor</strong> in a precise location and e<strong>li</strong>minates<br />
the need to a<strong>li</strong>gn the <strong>sensor</strong> within the ca<strong>li</strong>bration system. Both<br />
terrestrial and underwater <strong>sensor</strong>s can be ca<strong>li</strong>brated using the<br />
appropriate mounting fixture.<br />
The 1800-02 can be used to reca<strong>li</strong>brate the LI-1800 Portable<br />
Spectroradiometer, the LI-1800UW Underwater Spectroradiometer,<br />
the 1800-11 Remote Cosine Receptor or the LI-COR<br />
radiation <strong>sensor</strong>s <strong>li</strong>sted below.<br />
Quantum: LI-190SB, LI-190SA, LI-190SZ<br />
Underwater Quantum: LI-192SB, LI-192SA<br />
Photometric: LI-210SB, LI-210SA, LI-210SZ<br />
17
Operating Conditions: 0 to 50 C (± 0.25% total drift over this<br />
range).<br />
Power Requirements: 105-126/210-252 VAC,<br />
48-66 Hz, 6 Amp/3 Amp.<br />
Dimensions: 24.0 H × 27.0 W × 50.0 cm L<br />
(9.5" H × 10.5" W × 19.5" L).<br />
Weight: 16.0 Kg (35.0 lbs).<br />
ORDERING INFORMATION<br />
SPECIFICATIONS<br />
Ca<strong>li</strong>bration Wavelength Range: 300-1100 nm.<br />
Ca<strong>li</strong>bration Accuracy (traceable to NIST):<br />
300 nm ± 6.0%<br />
350-1000 nm ± 4.0%<br />
1100 nm ± 6.0%<br />
Lamp Type: 200 Watt Quartz Tungsten Halogen.<br />
Lamp Life: Typically 50 hours with less than ± 1% change.<br />
Ca<strong>li</strong>brations take 7-10 minutes including 5 minutes for lamp<br />
warm-up.<br />
1800-02 Optical Radiation Ca<strong>li</strong>brator: Includes one<br />
1800-02L Ca<strong>li</strong>brated Lamp, ca<strong>li</strong>bration data, mounting fixtures<br />
for LI-COR terrestrial <strong>sensor</strong>s, underwater <strong>sensor</strong>s and<br />
spectroradiometers.<br />
1800-02L Ca<strong>li</strong>brated Replacement Lamp:<br />
For 1800-02 Optical Radiation Ca<strong>li</strong>bration.<br />
Requires one for replacement.<br />
1800-02RA Spectral Radiance Accessory: For spectral<br />
radiance and radiance ca<strong>li</strong>brations from 300-1100 nm.<br />
A complete brochure is available on request.<br />
PORTABLE SPECTRORADIOMETER<br />
The LI-1800 Portable Spectroradiometer provides a fast, accurate<br />
method to obtain spectral radiation measurements in the<br />
field or in the laboratory. Its compact design, internal microcomputer,<br />
and innovative optical design provide the versati<strong>li</strong>ty to<br />
meet a wide variety of app<strong>li</strong>cations.<br />
What can the LI-1800 do for you?<br />
In remote sensing labs, the LI-1800 and 1800-12S External<br />
Integrating Sphere are used to characterize the spectral<br />
reflectance and transmittance of leaves. The data collected are<br />
correlated with other remote sensing techniques.<br />
LI-1800<br />
• Direct readout of spectroradiometric, radiometric and<br />
photometric measurements<br />
• Direct readout of CIE chromaticity coordinates<br />
• Fast scanning (over 30 nm s -1 )<br />
• Internal microcomputer<br />
• Up to 512K bytes RAM for data storage<br />
• Weatherproof design, battery operation<br />
At several field sites the LI-1800 is used for solar radiation monitoring.<br />
These data are used to characterize solar radiation for<br />
photovoltaic and energy conversion research, to generate solar<br />
simulation models, and for weathering studies of materials and<br />
coatings.<br />
The LI-1800 is just as much at home in the lab as it is in the<br />
field. Radiation qua<strong>li</strong>ty and quantity are measured in growth<br />
chambers and greenhouses for characterizing and verifying<br />
radiation sources, and to correlate plant growth with spectral<br />
output.<br />
The LI-1800 is also well suited for many other laboratory, industrial,<br />
and environmental app<strong>li</strong>cations including qua<strong>li</strong>tative and<br />
18
quantitative lamp measurements for photoresist processes, general<br />
lamp evaluation, qua<strong>li</strong>ty control, surface color measurements,<br />
photochemistry and photobiology.<br />
INNOVATIVE OPTICS<br />
The measurement optics of the LI-1800 has three major components<br />
— a filter wheel, holographic grating monochromator, and<br />
a si<strong>li</strong>con detector. The filter wheel contains seven order-sorting<br />
filters which e<strong>li</strong>minate second order harmonics and enhance<br />
stray <strong>li</strong>ght rejection by filtering out radiation that is not in the<br />
same spectral region as that being measured. The filter wheel<br />
also has a black target that serves as a dark reference for each<br />
scan.<br />
The dispersing element is a holographic grating monochromator<br />
which is available in two wavelength ranges; 300-850 nm with a<br />
4 nm bandwidth and 300-1100 nm with a 6 nm bandwidth.<br />
Optional monochromator s<strong>li</strong>ts are also available for changing the<br />
bandwidth and sensitivity to meet your app<strong>li</strong>cation.<br />
The monochromator is driven by a precision stepping motor<br />
under control of the internal microcomputer. Wavelength drive<br />
intervals are user selectable at 1, 2, 5 or 10 nm. The LI-1800’s<br />
high efficiency si<strong>li</strong>con detector and autoranging electronics<br />
allow scanning rates of over 30 nm per second.<br />
INTERNAL MICROCOMPUTER<br />
The heart of the LI-1800 system is the internal microcomputer<br />
which controls scanning and the collection, reduction and storage<br />
of data. Communication with the LI-1800 is accomp<strong>li</strong>shed<br />
using the 1800-01A Portable Terminal or any other RS-232<br />
terminal or computer. The LI-1800 is easy to use, yet powerful.<br />
A menu of simple commands covers all facets of operation from<br />
scanning to data output.<br />
SIMPLIFIED SCANNING<br />
Scanning is accomp<strong>li</strong>shed by one command; however, the<br />
LI-1800 lets you specify several parameters to get the scan you<br />
want, including wavelength <strong>li</strong>mits, wavelength drive interval,<br />
and the number of scans to average. Averaging scans provides<br />
accurate data under conditions of fluctuating radiation. Multiple<br />
scan averaging also improves sensitivity (signal to noise ratio) in<br />
low radiation conditions, since it reduces the noise level by a<br />
factor approaching the square root of the number of scans.<br />
After each scan the LI-1800 stores your data in its internal RAM<br />
memory. Standard memory in the LI-1800 is 256K bytes and is<br />
expandable to 512K bytes. The standard 256K memory typically<br />
holds 200 scans from 300-1100 nm (2 nm steps) or 530 scans<br />
from 400-700 nm.<br />
DATA REDUCTION<br />
The LI-1800’s built-in data reduction routines calculate irradiance,<br />
radiance, CIE chromaticity coordinates, illuminance,<br />
luminance, photon flux density, the ratio of spectral irradiance in<br />
two regions of a scan, and more. A data file can also be plotted<br />
on the 6000-03B Plotter/Printer using the LI-1800’s plotting<br />
routine.<br />
SPECIFICATIONS<br />
Holographic Grating Monochromator Options<br />
LI-1800/12 LI-1800/22<br />
Wavelength Range: 300-850 nm 300-1100 nm<br />
Standard Bandwidth<br />
(1/2 mm s<strong>li</strong>ts): 4 nm 6 nm<br />
Wavelength Accuracy: ± 1.5 nm ± 2 nm<br />
Wavelength<br />
Repeatabi<strong>li</strong>ty: ± 0.5 nm ± 0.5 nm<br />
Linear Dispersion: 8 nm/mm 12 nm/mm<br />
Grating:<br />
1200 grooves/mm 800 grooves/mm<br />
Automatic<br />
Filter Wheel: 6 filters 7 filters<br />
Noise Equivalent Irradiance<br />
(Standard cosine receptor, W cm -2 nm -1 )<br />
300-850 nm 300-1100 nm<br />
300 nm 6 × 10 -8 7 × 10 -8<br />
350 nm 4 × 10 -8 4 × 10 -8<br />
400 nm 2.5 × 10 -8 1.5 × 10 -8<br />
500-800 nm 8 × 10 -9 8 × 10 -9<br />
800-850 nm 2.5 × 10 -8 —<br />
800-1040 nm — 6 × 10 -9<br />
1100 nm — 1.5 × 10 -8<br />
Noise Equivalent Irradiance<br />
(1800-11 Remote Cosine Receptor, W cm -2 nm -1 )<br />
300-850 nm 300-1100 nm<br />
350 nm 2 × 10 -7 2 × 10 -7<br />
400 nm 1 × 10 -7 7 × 10 -8<br />
500-800 nm 3 × 10 -8 3.5 × 10 -8<br />
800-850 nm 1 × 10 -8 —<br />
800-1040 nm — 3 × 10 -8<br />
1100 nm — 6 × 10 -8<br />
NOTE: NEI is the noise of the instrument detector and amp<strong>li</strong>fier expressed in<br />
terms of the irradiance necessary to generate a detector output of an equivalent<br />
size. NEI values given are for standard 1/2 mm s<strong>li</strong>ts. Changing to 1 mm s<strong>li</strong>ts<br />
typically increases the sensitivity and reduces the NEI 3 to 4 times. The 1/4 mm<br />
s<strong>li</strong>ts decrease the sensitivity and increase the NEI 3 to 4 times.<br />
Maximum Irradiance Levels (W cm -2 nm -1 )<br />
300-400 nm 5 × 10 -3<br />
400-1000 nm > 1 × 10 -3<br />
Maximum irradiance levels are for 1/2 mm s<strong>li</strong>ts with standard<br />
teflon cosine receptor and filters.<br />
19
Wavelength Drive Intervals: 1, 2, 5 or 10 nm (user selectable).<br />
Scanning: Single scan, multiple scans with automatic scan<br />
averaging, or single wavelength monitoring (sampled once<br />
per second).<br />
Scanning Speed:<br />
20 nm/second for 1 nm steps.<br />
30 nm/second for 2 nm steps.<br />
35 nm/second for 5 nm steps.<br />
40 nm/second for 10 nm steps.<br />
Total scan time for 300 to 1100 nm in 2 nm steps is 27 seconds.<br />
Ca<strong>li</strong>bration: The LI-1800 is initially ca<strong>li</strong>brated at the factory.<br />
The 1800-02 Ca<strong>li</strong>bration System can be used for user reca<strong>li</strong>bration,<br />
or the LI-1800 can be returned for factory reca<strong>li</strong>bration.<br />
Ca<strong>li</strong>bration Accuracy:<br />
300 nm ±10%<br />
450 nm ± 5%<br />
550 nm ± 4%<br />
650-800 nm ± 3%<br />
1100 nm ± 5% (under controlled conditions)<br />
Ca<strong>li</strong>bration Stabi<strong>li</strong>ty: Typically
OPTICAL ACCESSORIES<br />
1800-12S External Integrating Sphere: With the 1800-12S, the<br />
LI-1800 becomes an even more powerful integrating sphere<br />
based system for measurements ranging from total reflectance<br />
and transmittance to color measurements of objects. Whether<br />
you’re measuring leaf spectral properties in the field, or qua<strong>li</strong>ty<br />
control, the 1800-12S provides the portabi<strong>li</strong>ty to meet all your<br />
measurement needs.<br />
1<br />
2<br />
3<br />
For measurements on thin samples, such as leaves, paper, or<br />
cloth, the samples can be clamped onto the sample port for measurement.<br />
For surface reflectance and color measurements of<br />
larger objects, the sample clamp can be removed and the integrating<br />
sphere placed directly on the object’s surface.<br />
Measurements are taken by placing the illuminator in the reference<br />
port and taking a reference scan with the LI-1800. Barium<br />
sulfate (BaSO 4 ) is the reference material and is also used to coat<br />
the walls of the 1800-12S. After a reference scan, the illuminator<br />
is moved to the reflectance or transmittance port so the<br />
source can shine on or through the object (respectively).<br />
The reflectance or transmittance data files stored in the LI-1800<br />
are then divided by the reference data file to produce a file<br />
containing the total (diffuse plus specular) spectral reflectance or<br />
transmittance. This data can also be used to calculate the CIE<br />
chromaticity coordinates of the measured object by choosing<br />
from standard sources A, E, D65 (stored in the LI-1800’s software)<br />
or a user-entered standard.<br />
Typical app<strong>li</strong>cations for the 1800-12S include leaf reflectance,<br />
transmittance and absorptance in crop canopy studies; color<br />
measurements and qua<strong>li</strong>ty control of surface coatings, fabrics,<br />
paper, and textiles. Other materials exhibiting marked directional<br />
reflection differences due to surface texture can also be measured.<br />
Integrating sphere geometry of the 1800-12S minimizes<br />
the effects surface texture can have on the type of geometry used<br />
in the measurement.<br />
1800-06 Telescope/Microscope Receptor: Remote measurements<br />
of spectral radiance, irradiance, luminance, illuminance,<br />
reflectance, or color measurements are all possible using the<br />
1800-06 Telescope-Microscope Receptor.<br />
The 1800-06 consists of a receptor body to which a number of<br />
optional lens accessories can be attached. A wide selection of<br />
objective lenses and three field of view (FOV) apertures offer<br />
flexibi<strong>li</strong>ty in collecting radiant power from submil<strong>li</strong>meter objects<br />
at close range, to large subjects at great distances. 35 mm<br />
camera lenses can also be used for added flexibi<strong>li</strong>ty.<br />
The 1800-06 body has an internal reflex viewing mirror that<br />
permits accurate, parallax-free viewing of the object to be<br />
measured. A six position aperture wheel provides apertures<br />
defining 3 different fields of view (for each lens option), a focusing<br />
screen, a diffuser for viewing highly polarized sources, and a<br />
dark position for checking the dark signal level.<br />
1. 1800-06 Receptor Body<br />
2. 1800-06B 3 Degree FOV Lens<br />
3. 1800-12S External Integrating Sphere<br />
The standard lens mount for the 1800-06 is a lockable s<strong>li</strong>ding<br />
tube which is used to mount and focus the optional lenses. The<br />
standard lens mount can also be replaced by the optional 1800-<br />
06D 35 mm camera lens mount (accepts Canon lenses with<br />
bayonet type mounts).<br />
Two telescopic lens options are available for the 1800-06; the<br />
1800-06A 15 Degree FOV Accessory and the 1800-06B 3<br />
Degree FOV Accessory. These options use quartz optics which<br />
have good radiation transmission characteristics from 310-1100<br />
nm. Both options A and B include an extension tube which<br />
allows closer focusing.<br />
Two lens options are also available for microscopic measurements.<br />
The 1800-06C is a microscope lens mount which accepts<br />
standard American Microscope Objects (AMO). Two objectives<br />
are available from LI-COR, the 1800-06E (7x objective) and the<br />
1800-06F (18x objective). Although any standard AMO objective<br />
will mount to the 1800-06, field diameters of at least 0.8<br />
mm are recommended if you wish to maintain full sensitivity of<br />
the 1800-06.<br />
The second microscope option is the quartz microscope which<br />
uses components from the 1800-06A and 1800-06B telescopic<br />
options to form a quartz microscope lens.<br />
21
RADIATION MEASUREMENT<br />
Much confusion has existed regarding the measurement of radiation.<br />
This report presents a comprehensive summary of the<br />
terminology and units used in radiometry, photometry, and the<br />
measurement of photosynthetically active radiation (PAR).<br />
Measurement errors can arise from a number of sources, and<br />
these are explained in detail. Finally, the conversion of radiometric<br />
and photometric units to photon units is discussed. In this<br />
report, the International System of Units (SI) is used unless<br />
noted otherwise (9).<br />
RADIOMETRY<br />
Radiometry (1) is the measurement of the properties of radiant<br />
energy (SI unit: joule, J), which is one of the many interchangeable<br />
forms of energy. The rate of flow of radiant energy, in the<br />
form of an electromagnetic wave, is called the radiant flux (unit:<br />
watt, W; 1 W = 1 J s -1 ) Radiant flux can be measured as it flows<br />
from the source (the sun, in natural conditions), through one or<br />
more reflecting, absorbing, scattering and transmitting media<br />
(the Earth's atmosphere, a plant canopy) to the receiving surface<br />
of interest (a photosynthesizing leaf) (8).<br />
Terminology and Units<br />
Radiant Flux is the amount of radiation coming from a source<br />
per unit time. Unit: watt, W.<br />
Radiant Intensity is the radiant flux leaving a point on the<br />
source, per unit so<strong>li</strong>d angle of space surrounding the point. Unit:<br />
watts per steridian, W sr -1 .<br />
Radiance is the radiant flux emitted by a unit area of a source or<br />
scattered by a unit area of a surface. Unit: W m -2 sr -1 .<br />
Irradiance is the radiant flux incident on a receiving surface<br />
from all directions, per unit area of surface. Unit: W m -2 .<br />
Absorptance is the fraction of the incident flux that is absorbed<br />
by a medium.<br />
Reflectance and Transmittance are equivalent terms for the<br />
fractions that are reflected or transmitted.<br />
Spectroradiometry: All the properties of the radiant flux<br />
depend on the wavelength of the radiation. The prefix spectral is<br />
added when the wavelength dependency is being described.<br />
Thus, the spectral irradiance is the irradiance at a given<br />
wavelength, per unit wavelength interval. The irradiance within<br />
a given waveband is the integral of the spectral irradiance with<br />
respect to wavelength (8). Unit: W m -2 nm -1 . Spectral measurements<br />
can be made using the LI-1800 Portable Spectroradiometer.<br />
Global solar radiation is the solar irradiance received<br />
on a horizontal surface (also referred to as the direct component<br />
of sun<strong>li</strong>ght plus the diffuse component of sky<strong>li</strong>ght received<br />
together on a horizontal surface). This physical quantity is measured<br />
by a pyranometer such as the LI-200SA. Unit: W m -2 .<br />
Direct Solar Radiation is the radiation emitted from the so<strong>li</strong>d<br />
angle of the sun's disc, received on a surface perpendicular to the<br />
axis of this cone, comprising mainly unscattered and unreflected<br />
solar radiation. This physical quantity is measured by a<br />
pyrhe<strong>li</strong>ometer. Unit: W m -2 .<br />
Diffuse Solar Radiation (sky radiation) is the downward<br />
scattered and reflected radiation coming from the whole<br />
hemisphere, with the exception of the so<strong>li</strong>d angle subtended by<br />
the sun's disc. Diffuse radiation can be measured by a<br />
pyranometer mounted on a shadow band, or calculated using<br />
global solar radiation and direct solar radiation. Unit: W m -2 .<br />
PHOTOSYNTHETICALLY<br />
ACTIVE RADIATION<br />
In the past there has been disagreement concerning units and<br />
terminology used in radiation measurements in conjunction with<br />
the plant sciences. It is LI-COR's po<strong>li</strong>cy to adopt the recommendations<br />
of the international committees, such as the Commission<br />
Internationale de I'Eclairage (CIE), the International Bureau of<br />
Weights and Measures, and the International Committee on<br />
Radiation Units. The International System of Units (SI) should<br />
be used wherever a suitable unit exists (9).<br />
Units<br />
The SI unit of radiant energy flux is the watt (W). There is no<br />
official SI unit of photon flux. A mole of photons is commonly<br />
used to designate Avogadro's number of photons (6.022 × 10 23<br />
photons). The einstein has been used in the past in plant science,<br />
however, most societies now recommend the use of the mole<br />
since the mole is an SI unit. When either of these definitions is<br />
used, the quantity of photons in a mole is equal to the quantity<br />
of photons in an einstein (1 mole = 1 einstein = 6.022 × 10 23<br />
photons). Note: The einstein has also been used in books on<br />
photochemistry, photobiology and radiation physics as the quantity<br />
of radiant energy in Avogadro's number of photons (5). This<br />
definition is not used in photosynthesis studies.<br />
Terminology<br />
LI-COR continues to follow the lead of the Crop Science<br />
Society of America, Committee on Terminology (10) and other<br />
societies (11) until international committees put forth further<br />
recommendations.<br />
22
®<br />
Photosynthetically Active Radiation (PAR) is defined as radiation<br />
in the 400 to 700 nm waveband. PAR is the general radiation<br />
term which covers both photon terms (7) and energy terms.<br />
Photosynthetic Photon Flux Density (PPFD) is defined as the<br />
photon flux density of PAR, also referred to as Quantum Flux<br />
Density. This is the number of photons in the 400-700 nm<br />
waveband incident per unit time on a unit surface. The ideal<br />
PPFD <strong>sensor</strong> responds equally to all photons in the 400-700 nm<br />
waveband and has a cosine response. This physical quantity is<br />
measured by a cosine (180˚) <strong>quantum</strong> <strong>sensor</strong> such as the<br />
LI-190SA or LI-192SA. The LI-191SA Line Quantum Sensor<br />
also measures PPFD. Figure 1 shows an ideal <strong>quantum</strong> response<br />
curve and the typical spectral response curve of LI-COR <strong>quantum</strong><br />
<strong>sensor</strong>s.<br />
Units: 1 µmol s -1 m -2 ≡ 1 µE s -1 m -2 ≡ 6.022 • 10 17 photons s -1 m -2 .<br />
PERCENT RELATIVE RESPONSE<br />
100<br />
80<br />
60<br />
40<br />
20<br />
0<br />
ULTRAVIOLET<br />
LI-COR<br />
QUANTUM SENSOR<br />
VIOLET<br />
BLUE<br />
IDEAL QUANTUM RESPONSE<br />
GREEN<br />
400 500 600 700<br />
Figure 1. Typical spectral response of LI-COR Quantum<br />
Sensors and a photosynthetic irradiance <strong>sensor</strong> vs.<br />
wavelength and ideal <strong>quantum</strong> response.<br />
Photosynthetic Photon Flux Fluence Rate (PPFFR) LI-COR<br />
introduced this term which is defined as the photon flux fluence<br />
rate of PAR, also referred to as Quantum Scaler Irradiance or<br />
Photon Spherical Irradiance. This is the integral of photon flux<br />
radiance at a point over all directions about the point. The ideal<br />
PPFFR <strong>sensor</strong> has a spherical collecting surface which exhibits<br />
the properties of a cosine receiver at every point on its surface<br />
(Figure 2) and responds equally to all photons in the 400-700 nm<br />
waveband (Figure 1). This physical quantity is measured by a<br />
spherical (4π collector) <strong>quantum</strong> <strong>sensor</strong> such as the LI-193SA.<br />
Units: 1 µmol s -1 m -2 ≡ 1 µE s -1 m -2 ≡ 6.022 × 10 17 photons s -1 m -2<br />
≡ 6.022 • 10 17 quanta s -1 m -2 .<br />
Note: There is no unique relationship between the PPFD and the<br />
PPFFR. For a col<strong>li</strong>mated beam at normal incidence, they are<br />
equal; while for perfectly diffuse radiation, the PPFFR is 4 times<br />
the PPFD. In practical situations the ratio will be somewhere<br />
between 1 and 4.<br />
YELLOW<br />
WAVELENGTH – NANOMETERS<br />
RED<br />
INFRARED<br />
Ø= 270°<br />
PHOTOMETRY<br />
Figure 2. Typical<br />
Angular Response of the<br />
LI-193SB Spherical<br />
Quantum Sensor.<br />
Photometry refers to the measurement of visible radiation (<strong>li</strong>ght)<br />
with a <strong>sensor</strong> having a spectral responsivity curve equal to the<br />
average human eye. Photometry is used to describe <strong>li</strong>ghting<br />
conditions where the eye is the primary <strong>sensor</strong>, such as illumination<br />
of work areas, interior <strong>li</strong>ghting, television screens, etc.<br />
Although photometric measurements have been used in the past<br />
in plant science, PPFD and irradiance are the preferred measurements.<br />
The use of the word "<strong>li</strong>ght" is inappropriate in plant<br />
research. The terms "ultraviolet <strong>li</strong>ght" and "infrared <strong>li</strong>ght"<br />
clearly are contradictory (8).<br />
The spectral responsivity curve of the standard human eye at<br />
typical <strong>li</strong>ght levels is called the CIE Standard Observer Curve<br />
(photopic curve), and covers the waveband of 380-770 nm. The<br />
human eye responds differently to <strong>li</strong>ght of different colors and<br />
has maximum sensitivity to yellow and green (Figure 3). In<br />
order to make accurate photometric measurements of various<br />
colors of <strong>li</strong>ght or from differing types of <strong>li</strong>ght sources, a<br />
photometric <strong>sensor</strong>'s spectral responsivity curve must match<br />
the CIE photopic curve very closely.<br />
PERCENT RELATIVE RESPONSE<br />
100<br />
80<br />
60<br />
40<br />
20<br />
0<br />
ULTRAVIOLET<br />
VIOLET<br />
Ø= 0°<br />
8<br />
6<br />
4<br />
2<br />
Ø= 180°<br />
PHOTOMETRIC<br />
SENSOR<br />
BLUE<br />
GREEN<br />
Ø= 90°<br />
400 500 600 700<br />
Figure 3. Typical spectral response of LI-COR Photometric<br />
Sensors vs. the CIE photopic response curve.<br />
YELLOW<br />
WAVELENGTH – NANOMETERS<br />
CIE PHOTOPIC CURVE<br />
RED<br />
INFRARED<br />
23
ENVIRONMENTAL DIVISION<br />
Terminology and Units (4)<br />
Luminous Flux is the amount of radiation coming from a source<br />
per unit time, evaluated in terms of a standardized visual<br />
response. Unit: lumen, lm.<br />
Luminous Intensity is the luminous flux per unit so<strong>li</strong>d angle in<br />
the direction in question. Unit: candela, cd. One candela is one<br />
lm sr -1 .<br />
Luminance is the quotient of the luminous flux at an element of<br />
the surface surrounding the point and propagated in directions<br />
defined by an elementary cone containing the given direction, by<br />
the product of the so<strong>li</strong>d angle of the cone and the area of the<br />
orthogonal projection of the element of the surface on a plane<br />
perpendicular to the given direction. Unit: cd m -2 ; also,<br />
lm sr -1 m -2 . This unit is also called the nit.<br />
Illuminance is defined as the density of the luminous flux<br />
incident at a point on a surface. Average illuminance is the<br />
quotient of the luminous flux incident on a surface by the area<br />
of the surface. This physical quantity is measured by a cosine<br />
photometric <strong>sensor</strong> such as the LI-210SA.<br />
Unit: lux, lx. One lux is one lm m -2 .<br />
MEASUREMENT ERRORS<br />
At a Controlled Environments Working Conference in Madison,<br />
Wisconsin, USA (1979), an official from the U.S. National<br />
Bureau of Standards (NBS) stated that one could not expect less<br />
than 10 to 25% error in radiation measurements made under<br />
non-ideal conditions. In order to clarify this area, the sources of<br />
errors which the researcher must be aware of when making<br />
radiation measurements have been tabulated. Refer also to the<br />
specifications given with each <strong>sensor</strong> for further details.<br />
Absolute Ca<strong>li</strong>bration Error<br />
Absolute ca<strong>li</strong>bration error depends on the source of the lamp<br />
standard and its estimated uncertainty at the time of ca<strong>li</strong>bration,<br />
accuracy of filament to <strong>sensor</strong> distance, a<strong>li</strong>gnment accuracy,<br />
stray <strong>li</strong>ght, and the lamp current measurement accuracy. Where<br />
it is necessary to use a transfer <strong>sensor</strong> (such as for solar ca<strong>li</strong>brations)<br />
additional error will be introduced. LI-COR <strong>quantum</strong> and<br />
photometric <strong>sensor</strong>s are ca<strong>li</strong>brated against a working quartz<br />
halogen lamp. These working quartz halogen lamps have been<br />
ca<strong>li</strong>brated against laboratory standards traceable to the NBS.<br />
Standard lamp current is metered to 0.035% accuracy.<br />
Microscope and laser a<strong>li</strong>gnment in the ca<strong>li</strong>bration setup reduce<br />
a<strong>li</strong>gnment errors to less than 0.1%. Stray <strong>li</strong>ght is reduced by<br />
black velvet to less than 0.1%. The absolute ca<strong>li</strong>bration<br />
accuracy is <strong>li</strong>mited to the uncertainty of the NBS traceable<br />
standard lamp. The absolute ca<strong>li</strong>bration specification for<br />
LI-COR <strong>sensor</strong>s is ±5% traceable to the NBS. This accuracy is<br />
conservatively stated and the error is typically ±3%. Absolute<br />
ca<strong>li</strong>brations and spectral responses of LI-COR <strong>sensor</strong>s have been<br />
checked by the National Research Council of Canada (NRC) to<br />
insure the accuracy and qua<strong>li</strong>ty of LI-COR ca<strong>li</strong>brations.<br />
Relative Error (Spectral Response Error)<br />
This error is also called actinity error or spectral correction error.<br />
This error is due to the spectral response of the <strong>sensor</strong> not<br />
conforming to the ideal spectral response. This error occurs<br />
when measuring radiation from any source which is spectrally<br />
different than the ca<strong>li</strong>bration source.<br />
The <strong>quantum</strong> and photometric <strong>sensor</strong> spectral response conformity<br />
is checked by LI-COR using a monochromator and ca<strong>li</strong>brated<br />
si<strong>li</strong>con photodiode. The spectral response of the <strong>sensor</strong> is<br />
achieved by the use of computer-tailored filter glass. Relative<br />
errors for various sources due to a non-ideal spectral response<br />
are checked by actual measurement and a computer program<br />
which uti<strong>li</strong>zes the source spectral irradiance data and the <strong>sensor</strong><br />
spectral response data.<br />
The relative error specifications given for LI-COR <strong>quantum</strong><br />
and photometric <strong>sensor</strong>s are for use in growth chambers,<br />
day<strong>li</strong>ght, greenhouses, plant canopies and aquatic conditions.<br />
When used with sources that have strong spectral <strong>li</strong>nes such<br />
as gas lamps or lasers, this error could be larger depending<br />
on the location of the <strong>li</strong>nes.<br />
The LI-COR pyranometer measures irradiance from the sun plus<br />
sky. The LI-200SA is not spectrally ideal (equal spectral<br />
response from 280-2800 nm). See Figure 4. Therefore, it<br />
should be used only under natural, unobstructed day<strong>li</strong>ght<br />
conditions. NOAA states in a test report that for clear, unobstructed<br />
day<strong>li</strong>ght conditions, the LI-COR pyranometer compares<br />
very well with class one thermopile pyranometers (3). The<br />
LI-200SA is a WMO (World Meteorological Organization) class<br />
two pyranometer.<br />
The LI-200SA should not be used under spectrally different radiation<br />
(than the sun), such as in growth chambers, greenhouses,<br />
and plant canopies. Under such artificial or shaded conditions, a<br />
thermopile pyranometer should be used.<br />
SPECTRAL IRRADIANCE (Sλ) - W m -2 A -1<br />
0.25<br />
0.20<br />
0.15<br />
0.10<br />
0.05<br />
SOLAR IRRADIATION CURVE OUTSIDE ATMOSPHERE<br />
SOLAR IRRADIATION CURVE AT SEA LEVEL<br />
CURVE FOR BLACKBODY CT 5900°K<br />
0 3<br />
H O 2<br />
0 H O 2 2<br />
® PYRANOMETER SENSOR<br />
H O 2<br />
H O 2H<br />
O<br />
2<br />
H O 2<br />
H O, CO<br />
2 2<br />
0 3<br />
50<br />
H O, CO<br />
2 2 H O, CO<br />
2 2<br />
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<br />
WAVELENGTH ( µ )<br />
Figure 4. The LI-200SA Pyranometer spectral<br />
response is illustrated along with the energy distribution<br />
in the solar spectrum (5).<br />
100<br />
PERCENT RELATIVE RESPONSE TO IRRADIANCE<br />
24
Spatial Error<br />
This error is caused by a <strong>sensor</strong> not responding to radiation at<br />
various incident angles. Spatial error consists of the cosine error<br />
(or the angular error) and azimuth error.<br />
Cosine Error<br />
A <strong>sensor</strong> with a cosine response (follows Lambert's cosine<br />
law) allows measurement of flux densities through a given<br />
plane, i.e. flux densities per unit area. When a parallel beam<br />
of radiation of given cross-sectional area spreads over a flat<br />
surface, the area that it covers is inversely proportional to<br />
the cosine of the angle between the beam and a plane nor<br />
mal to the surface. Therefore, the irradiance due to the beam<br />
is proportional to the cosine of the angle. A radiometer,<br />
whose response to beams coming from different directions<br />
follows the same relationship, is said to be "cosine-corrected"<br />
(6). A <strong>sensor</strong> without an accurate cosine correction can<br />
give a severe error under diffuse radiation conditions within<br />
a plant canopy, at low solar elevation angles, under fluorescent<br />
<strong>li</strong>ghting, etc.<br />
Cosine response is measured by placing the <strong>sensor</strong> on a<br />
platform which can be adjusted to rotate the <strong>sensor</strong> about an<br />
axis placed across the center of the measuring surface. A<br />
col<strong>li</strong>mated source is directed at normal incidence and the<br />
output of the <strong>sensor</strong> is measured as the angle of incidence is<br />
varied. The cosine error at angle 0 is the percent difference<br />
of the ratio of the measured output at angle 0 and normal<br />
incidence (angle 0°) as compared to the cosine of angle 0.<br />
This is repeated for various azimuth angles as necessary.<br />
The LI-190SA, LI-200SA and LI-210SA are fully corrected<br />
cosine <strong>sensor</strong>s. These <strong>sensor</strong>s have a typical cosine error of<br />
less than 5% up to an 80° angle of incidence. Totally diffuse<br />
radiation introduces a cosine error of approximately 2.5%.<br />
For sun plus sky at a sun elevation of 30° (60° angle of<br />
incidence), the error is ≈2%. The LI-192SA <strong>sensor</strong> has a<br />
s<strong>li</strong>ghtly greater cosine error since this <strong>sensor</strong> has a cosine<br />
response optimized for both air and water. The LI-191SA<br />
uses uncorrected acry<strong>li</strong>c diffusers and has a greater error at<br />
high angles of incidence. For totally diffuse radiation, the<br />
error is ≈8%. For conditions within canopies, the error is<br />
less because the radiation is not totally diffuse.<br />
Angular Error<br />
A spherical PPFFR <strong>sensor</strong> measures the total flux<br />
incidence on its spherical surface divided by the crosssectional<br />
area of the sphere. Angular error is measured by<br />
directing a col<strong>li</strong>mated source at normal incidence and<br />
rotating the <strong>sensor</strong> 360° about an axis directly through the<br />
center of the sphere at 90° from normal incidence. This is<br />
repeated for various azimuth angles as necessary to<br />
characterize the <strong>sensor</strong>.<br />
The LI-193SA angular error is due to variations in density<br />
in the diffusion sphere and the sphere area lost because of<br />
the <strong>sensor</strong> base (Figure 2). This error is less than -10% for<br />
total because the upwel<strong>li</strong>ng radiation is much smaller than<br />
the downwel<strong>li</strong>ng radiation.<br />
Azimuth Error<br />
This is a subcategory of both cosine and angular error. It is<br />
specified separately at a particular angle of incidence. This<br />
error is the percent change of the <strong>sensor</strong> output as the <strong>sensor</strong><br />
is rotated about the normal axis at a particular angle of<br />
incident radiation. This error is less than ±1% at 45° for the<br />
LI-190SA, LI-192SA, LI-200SA, and LI-210SA <strong>sensor</strong>s.<br />
The error is less than ±3% for the LI-191SA and LI-193SA<br />
<strong>sensor</strong>s.<br />
Displacement Error<br />
In highly turbid waters, the LI-193SA Spherical Sensor will indicate<br />
high PPFFR values due to the displacement of water by the<br />
<strong>sensor</strong> sphere volume. This is because the point of measurement<br />
is taken to be at the center of the sphere, but the attenuation<br />
which would have been provided by the water within the sphere<br />
is absent. This error is typically +6% for water with an attenuation<br />
coefficient of 3 m -1 (2).<br />
Tilt Error<br />
Tilt error exists when a <strong>sensor</strong> is sensitive to orientation due<br />
to the effects of gravity. This exists primarily in thermopile<br />
type detectors. Si<strong>li</strong>con type detectors do not have this error.<br />
All LI-COR <strong>sensor</strong>s are of the latter type and have no tilt error.<br />
This error in the LI-200SA Pyranometer is nonexistent and has<br />
an advantage over thermopile type detectors for solar radiation<br />
measurements (3).<br />
Linearity Error<br />
Linearity error exists when a <strong>sensor</strong> is not able to follow proportionate<br />
changes in radiation. The type of si<strong>li</strong>con detectors used in<br />
LI-COR <strong>sensor</strong>s have a <strong>li</strong>nearity error of less than ±1% over<br />
seven decades of dynamic range.<br />
Fatigue Error<br />
Fatigue error exists when a <strong>sensor</strong> exhibits hysteresis. This is<br />
common in selenium-based illumination meters and can add a<br />
considerable error. For this reason, LI-COR <strong>sensor</strong>s incorporate<br />
only si<strong>li</strong>con detectors which exhibit no fatigue error.<br />
Temperature Coefficient Error<br />
Temperature coefficient error exists when the output of a <strong>sensor</strong><br />
changes with a constant input. This error is typically less than<br />
±0.1% per °C for the LI-190SA, LI-191SA, LI-192SA,<br />
25
LI-193SA, and LI-210SB <strong>sensor</strong>s. This error is s<strong>li</strong>ghtly higher<br />
for the LI-200SA.<br />
Response Time Error<br />
This error exists when the source being measured changes<br />
rapidly during the period of measurement.<br />
Averaging:<br />
Large errors can exist when measuring radiation<br />
under rapidly changing conditions such as changing cloud<br />
cover and wind if measuring within a crop canopy, and<br />
waves if measuring underwater. The use of an integrating<br />
meter to average the reading will e<strong>li</strong>minate this error.<br />
Instantaneous:<br />
When radiation measurements are desired over a period of<br />
time (much less than the response time of the system), large<br />
errors can exist. For example, if one were to measure the<br />
radiation from a pulsed source (such as a gas discharge flash<br />
lamp) with a typical system designed for environmental<br />
measurements, the reading would be meaningless. Such a<br />
measurement should not be made with LI-COR instruments<br />
without consultation with LI-COR.<br />
Long-Term Stabi<strong>li</strong>ty Error<br />
This error exists when the ca<strong>li</strong>bration of a <strong>sensor</strong> changes with<br />
time. This error is usually low for <strong>sensor</strong>s using high qua<strong>li</strong>ty<br />
si<strong>li</strong>con photovoltaic photodiodes and glass filters. LI-COR uses<br />
only high qua<strong>li</strong>ty components. The use of Wratten filters and/or<br />
inexpensive si<strong>li</strong>con or selenium cells add significantly to longterm<br />
stabi<strong>li</strong>ty error. The stabi<strong>li</strong>ty error of LI-COR <strong>sensor</strong>s is typically<br />
±2% per year.<br />
Important: Customers should have their <strong>sensor</strong>s reca<strong>li</strong>brated<br />
every two years.<br />
Immersion Effect Error<br />
A <strong>sensor</strong> with a diffuser for cosine correction will have an<br />
immersion effect when used under water. Radiation entering the<br />
diffuser scatters in all directions within the diffuser, with more<br />
radiation lost through the water-diffuser interface than in the<br />
case when the <strong>sensor</strong> is in the air. This is because the airdiffuser<br />
interface offers a greater ratio of indices of refraction<br />
than the water-diffuser interface. LI-COR provides a typical<br />
immersion effect correction factor for the underwater <strong>sensor</strong>s.<br />
Immersion effect error is the difference between this typical<br />
figure and the actual figure for a given <strong>sensor</strong> in a particular<br />
environment. Since LI-COR test measurements are done in clear<br />
water, the error is also dependent on other variables such as<br />
turbidity, sa<strong>li</strong>nity, etc. Immersion effect error is typically ±2%<br />
or less. A complete report on the immersion effect properties of<br />
LI-COR underwater <strong>sensor</strong>s is available from LI-COR.<br />
Surface Variation Error<br />
In general, the absolute responsivity and the relative spectral<br />
responsivity are not constant over the radiation-sensitive surface<br />
of <strong>sensor</strong>s. This error has <strong>li</strong>ttle effect in environmental measurements<br />
except for spatial averaging <strong>sensor</strong>s such as the<br />
LI-191SA. This error is < ±7% for the LI-191SA.<br />
User Errors<br />
Spatial User Error<br />
This is different than <strong>sensor</strong>-caused spatial error.<br />
Spatial user error can be introduced by using a single small<br />
<strong>sensor</strong> to characterize the radiation profile within a crop<br />
canopy or growth chamber. The flux density measured on a<br />
given plane can vary considerably due to shadows and<br />
sunflecks. To neglect this in measurements can introduce<br />
errors up to 1000%. Multiple <strong>sensor</strong>s or <strong>sensor</strong>s on track<br />
scanners can be used to minimize this error. If track<br />
scanners are used, the output of the <strong>sensor</strong>s must be<br />
integrated.<br />
The LI-191SA Line Quantum Sensor, which spatially<br />
averages radiation over its one meter length, minimizes this<br />
error and allows one person to easily make many measurements<br />
in a short period of time. Another method, although<br />
not as accurate, is to use an integrating meter and the<br />
LI-190SA <strong>quantum</strong> Sensor and physically scan the <strong>sensor</strong><br />
by hand within the canopy while integrating the output with<br />
the meter.<br />
Another type of spatial user error can be caused by<br />
misapp<strong>li</strong>cation of a cosine-corrected <strong>sensor</strong> where a<br />
spherical <strong>sensor</strong> would give a more accurate measurement.<br />
An example is in underwater photosynthetic radiation<br />
measurements when studying phytoplankton.<br />
User Setup/App<strong>li</strong>cation Errors<br />
These errors include such causes as:<br />
• Reflections or obstructions from clothing, buildings,<br />
boats, etc.<br />
• Dust, flyspecks, seaweeds, bird droppings, etc.<br />
• Shock, causing permanent damage of optics within<br />
the <strong>sensor</strong>.<br />
• Submersion of terrestrial <strong>sensor</strong>s in water for an<br />
extended period (partial or total). Rain doesn't affect<br />
the <strong>sensor</strong>s since they are completely weatherproof.<br />
• Use of the incorrect ca<strong>li</strong>bration constant.<br />
• Incorrect interpolation of analog meters.<br />
• Using the wrong meter function.<br />
• Failure to have <strong>sensor</strong>s reca<strong>li</strong>brated periodically.<br />
26
Readout Error<br />
This error is due to the readout instrument as distinguished from<br />
the <strong>sensor</strong>. Zero drift, temperature, battery voltage, electronic<br />
stabi<strong>li</strong>ty, <strong>li</strong>ne voltage, humidity and shock are all factors which<br />
can contribute to readout error. The use of electronic circuitry<br />
such as chopper-stabi<strong>li</strong>zed amp<strong>li</strong>fiers and voltage regulators in<br />
LI-COR meters largely e<strong>li</strong>minates many of these problems: zero<br />
drift, temperature, battery voltage, electronic stabi<strong>li</strong>ty, <strong>li</strong>ne<br />
voltage.<br />
Total Error<br />
The errors given are largely independent of each other and are<br />
random in polarity and magnitude. Therefore, they can be<br />
summed in quadrature (the square root of the sum of the<br />
squares). The total error is shown below for an LI-190SA<br />
Quantum Sensor and LI-COR meters when used for measuring<br />
<strong>li</strong>ghting in a typical growth chamber or natural day<strong>li</strong>ght over a<br />
temperature range of 15° to 35°C.<br />
Typical Error<br />
Absolute Error<br />
5% max., 3% typical<br />
Relative (spectral response) Error 5%<br />
Spatial (cosine) Error 2%<br />
Displacement Error 0%<br />
Tilt Error 0%<br />
Linearity Error 0%<br />
Fatigue Error 0%<br />
Sensor Temperature Coefficient Error 1 % (0.1% per °C)<br />
Response Time Error 0%<br />
Long-term Stabi<strong>li</strong>ty Error<br />
2% (2% per year)<br />
Immersion Effect Error 0%<br />
Surface Variation Error 0%<br />
Readout Error 1%<br />
User Error ?<br />
The total error = Square Root (5 × 5 + 5 × 5 + 2 × 2 + 1 × 1) =<br />
7.6%. All of the above errors are minimized by LI-COR through<br />
design and ca<strong>li</strong>bration. While this error seems reasonably low, it<br />
must be remembered that no user error has been added, and that<br />
statistically it is possible that all the errors could be of the same<br />
polarity. The sum of the errors (less the user error) could equal<br />
21% in the worst case. The absolute error is conservatively stated<br />
and is more typically ±3%. User error in vegetation canopies<br />
where shadows and sunflecks exist can be very large (1000%)<br />
and one of the methods described under Spatial User Error<br />
should be employed.<br />
When purchasing a radiation measuring system, it is necessary<br />
to insure that the spatial (cosine, etc.) and relative spectral<br />
response errors are as low as possible. These two errors depend<br />
upon the skill and expertise of the designer and manufacturer.<br />
Some manufacturers de<strong>li</strong>berately do not give specifications for<br />
these errors and the user can expect large errors. The absolute<br />
error is largely dependent on the NBS lamp standard.<br />
Minimization of this error can be achieved by the more experienced<br />
companies through the use of precise techniques and<br />
expensive capital equipment. In order to insure long-term<br />
stabi<strong>li</strong>ty, it is necessary that the manufacturer use the highest<br />
qua<strong>li</strong>ty si<strong>li</strong>con photovoltaic/photodiodes and only the best glass<br />
filters. Modern electronic readout instruments virtually e<strong>li</strong>minate<br />
readout error.<br />
The user should be aware of all the types of errors that can<br />
occur, particularly the relative and spatial errors, since these can<br />
add considerably to the total error. LI-COR has and continues to<br />
put forth a considerable effort to insure that the spectral and<br />
cosine response of all <strong>quantum</strong> and photometric <strong>sensor</strong>s are as<br />
nearly ideal as optically possible. This assures LI-COR<br />
customers of the best possible accuracy.<br />
CONVERSION OF UNITS<br />
Conversion of Photon Units to Radiometric Units<br />
Conversion of <strong>quantum</strong> <strong>sensor</strong> output in µmol s -1 m -2 (400-700<br />
nm) to radiometric units in W m -2 (400-700 nm) is comp<strong>li</strong>cated.<br />
The conversion factor will be different for each <strong>li</strong>ght source, and<br />
the spectral distribution curve of the radiant output of the source<br />
(W λ ; W m -2 nm -1 ) must be known in order to make the conversion.<br />
The accurate measurement of W λ is a difficult task, which<br />
should not be attempted without adequate equipment and ca<strong>li</strong>bration<br />
faci<strong>li</strong>ties. The radiometric quantity desired is the integral<br />
of W λ over the 400-700 nm range, or:<br />
700<br />
W = W d<br />
∫ λ λ<br />
1.<br />
T<br />
At a given wavelength λ, the number of photons per second is:<br />
where h = 6.63 • 10 -34 J•s (Planck's constant), c = 3.00 • 10 8 m s -1<br />
(velocity of <strong>li</strong>ght) and λ is in nm. hc/λ is the energy of one photon.<br />
Then, the total number of photons per second in the 400-<br />
700 nm range is:<br />
700 W<br />
d<br />
∫ hc /<br />
λλ λ<br />
3.<br />
This is the integral which is measured by the <strong>sensor</strong>. If R is the<br />
reading of the <strong>quantum</strong> <strong>sensor</strong> in µmol s -1 m -2 (1 µmol s -1 m -2 ≡<br />
6.022 • 10 17 photons s -1 m -2 ), then:<br />
400<br />
W<br />
photons s<br />
-1 λ<br />
=<br />
hc/ λ<br />
400<br />
700<br />
17 W<br />
6.022 × 10 (R) =<br />
λ<br />
∫ 400 hc/ λ<br />
dλ<br />
Combining Eq. (1) and Eq. (4) gives<br />
700<br />
Wd<br />
17 ∫ λ λ<br />
400<br />
WT<br />
= 6.022 × 10 (RHc)<br />
5.<br />
700<br />
λWd<br />
∫ λ λ<br />
400<br />
To achieve the two integrals, discrete summations are necessary.<br />
Also, since W λ appears in both the numerator and the denominator,<br />
the norma<strong>li</strong>zed curve N λ may be substituted for it. Then:<br />
∑<br />
Nλ<br />
∆λ<br />
i<br />
17 i<br />
WT<br />
= 6.022 × 10 (RHc)<br />
∑λiNλ<br />
∆λ<br />
i<br />
i<br />
2.<br />
4.<br />
6.<br />
27
where ∆λ is any desired wavelength interval, λ i is the center<br />
wavelength of the interval and N λi is the norma<strong>li</strong>zed radiant<br />
output of the source at the center wavelength. In final form this<br />
becomes:<br />
∑Nλi<br />
i W T (R)<br />
N<br />
W m -2<br />
≈ 119.<br />
8<br />
7.<br />
where R is the reading in µmol s -1 m -2 .<br />
The following procedure should be used in conjunction<br />
with Eq. (7).<br />
1 . Divide the 400-700 nm range into 'i' intervals of<br />
equal wavelength spacing ∆λ.<br />
2. Determine the center wavelength (λ i ) of each<br />
interval.<br />
3. Determine the norma<strong>li</strong>zed radiant output of the<br />
source (N λi<br />
) at each of the center wavelengths.<br />
4. Sum the norma<strong>li</strong>zed radiant outputs as determined<br />
in Step 3 to find<br />
∑<br />
Nλ<br />
i<br />
5. Multiply the center wavelength by the norma<strong>li</strong>zed<br />
radiant output at that wavelength for each interval.<br />
6. Sum the products determined in Step 5 to find<br />
7. Use Eq. (7) to find W T in W m -2 , where R is the<br />
<strong>quantum</strong> <strong>sensor</strong> output in µmol s -1 m -2 .<br />
The following approximation assumes a flat spectral distribution<br />
curve of the source over the 400-700 nm range (equal spectral<br />
irradiance over the 400-700 nm range) and is shown as an<br />
example.<br />
Given: i = 1<br />
∆λ = 300 nm<br />
λ i = 550 nm<br />
i<br />
This conversion factor is within ±8.5% of the factors determined<br />
by McCree as <strong>li</strong>sted in Table 1 (8).<br />
Conversion of Photon Units to Photometric Units<br />
∑<br />
⎛ N(550) ⎞ 119.<br />
8 (R)<br />
-2<br />
WT<br />
≈ 119.8 (R) ⎜<br />
⎟ = = 022 . (R) W m<br />
⎝ 550 × N(550) ⎠ 550<br />
or<br />
1W m -2 ≈ 4.6 µmol s -1 m -2<br />
∑<br />
i<br />
λ i<br />
λ<br />
i<br />
i<br />
λ<br />
iNλ<br />
i<br />
where y λ is the luminosity coefficient of the standard CIE<br />
curve with y λ = 1 at 550 nm and W λ is the spectral irradiance<br />
(W m -2 nm -1 ).<br />
b) Replace Eq. (5) with<br />
700<br />
y W d<br />
17 ∫ λ λ λ<br />
400<br />
Lux = 683 (6.022 × 10 ) (RHc)<br />
700<br />
λWd<br />
∫ λ λ<br />
400<br />
c) Replace Eq. (6) with<br />
y N ∆λ<br />
d) Replace Eq. (7) with<br />
Lux = 8.17×<br />
10 (R)<br />
∑λ<br />
Nλi<br />
e) Replace Step 4 with:<br />
i<br />
4a) Multiply the luminosity coefficient (y λ ) of the<br />
center wavelength by the norma<strong>li</strong>zed radiant<br />
output (N λ ) at the wavelength for each interval<br />
4b). Sum the products determined in Step 4a to find<br />
The following approximation assumes a flat spectral distribution<br />
curve of the source over the 400-700 nm range (equal spectral<br />
irradiance over the 400-700 nm range) and shown as an<br />
example.<br />
Given:<br />
i = 1 to 31<br />
∆λ = 10 nm<br />
λ 1 = 400, λ 2 = 410, λ 3 = 420.... λ 31 = 700<br />
Ν λ = 1 for all wavelengths<br />
y λ1<br />
= 0.0004, y λ2<br />
= 0.0012, y λ3<br />
= 0.004....y λ31<br />
= 0.0041<br />
Or,<br />
17<br />
Lux = 683 (6.022 × 10 ) (RHc)<br />
1000 lux = 1 klux = 19.5 µmol s -1 m -2<br />
Table 1. Approximate conversion factors for various <strong>li</strong>ght<br />
sources.<br />
(8) (PAR waveband 400-700 nm)<br />
To convert<br />
∑<br />
i<br />
4<br />
∑<br />
∑<br />
i<br />
∑<br />
λ<br />
i<br />
λ<br />
λiNλ<br />
∆λ<br />
i<br />
i<br />
∑<br />
i<br />
yλ<br />
Nλ<br />
i<br />
i<br />
yλ<br />
Nλ<br />
yλi<br />
4 i<br />
10.682<br />
Lux = 8.17× 10 (R) = 817 . × 10 (R)<br />
⎛ ⎞<br />
⎝ 17050 ⎠<br />
∑<br />
4<br />
λi<br />
i<br />
Lux = 51.2 R, where R is in µmol s -1 m -2<br />
Light Source<br />
Day<strong>li</strong>ght Metal Sodium Mercury White Incand.<br />
ha<strong>li</strong>de (HP) fluor.<br />
Multiply by<br />
i<br />
i<br />
i<br />
To convert photon units (µmol s -1 m -2 , 400-700 nm) to photometric<br />
units (lux, 400-700 nm), use the above procedure, except<br />
a) Replace Eq. (1) with<br />
700<br />
Lux = 683 y W d<br />
∫ λ λ λ<br />
400<br />
Wm -2 (PAR) to 4.6 4.6 5.0 4.7 4.6 5.0<br />
µmol s -1 m -2 (PAR)<br />
klux to 18 14 14 14 12 20<br />
µmol s -1 m -2 (PAR)<br />
klux to W m -2 (PAR) 4.0 3.1 2.8 3.0 2.7 4.0<br />
28
Your comments on the subjects addressed in this report or any<br />
other measurement problems are always welcome and will be<br />
treated as valuable inputs.<br />
Wil<strong>li</strong>am W. Biggs, Author<br />
Excerpted from: Advanced Agricultural Instrumentation.<br />
Proceedings from the NATO Advanced Study Institute on<br />
“Advanced Agricultural Instrumentation”, 1984. W.G. Gensler<br />
(ed.), Martinus Nijhoff Pub<strong>li</strong>shers, Dordrect, The Netherlands.<br />
RADIATION MEASUREMENT REFERENCES<br />
1. CIE (Commission Internationale de l’Eclairage). 1970.<br />
International <strong>li</strong>ghting vocabulary, 3rd edn. Bureau Central<br />
de la CIE. Paris<br />
2. Combs, W.S., Jr., 1977. The measurement and prediction of<br />
irradiances available for photosynthesis by phytoplankton in<br />
lakes. Ph.D. Thesis, Univ. of Minnesota, Limnology.<br />
3. Flowers, E.C. 1978. Comparison of solar radiation <strong>sensor</strong>s<br />
from various manufacturers. In: 1978 annual report from<br />
NOAA to the DOE.<br />
4. Illuminating Engineering Society of North America. 1981.<br />
Nomenclature and definitions for illuminating engineering.<br />
Pub<strong>li</strong>cation RP-16, ANSI/IES RP-116-1980. New York.<br />
5. Incoll, L.D., S.P. Long and M.A. Ashmore. 1981. SI units in<br />
pub<strong>li</strong>cations in plant science. In: Commentaries in Plant Sci.<br />
Vol. 2, pp. 83-96, Pergamon, Oxford.<br />
6. Kondratyev, K. Ya. 1969. Direct solar radiation. In:<br />
Radiation in the atmosphere. Academic Press, New York,<br />
London.<br />
7. McCree, K.J. 1972. Test of current definitions of photosynthetically<br />
active radiation against leaf photosynthesis<br />
data. Agric. Meteorol. 10:443-453.<br />
8. _________. 1981. Photosynthetically active radiation. In:<br />
Physiological plant ecology. Lang, O.L., P. Novel, B.<br />
Osmond and H. Ziegler (ed). Vol. 12A, Encyclopedia of<br />
plant physiology (new series). Springer-Verlag. Ber<strong>li</strong>n,<br />
Heidelberg, New York.<br />
9. Page, C.H. and P. Vigoureux (ed). 1977. The international<br />
system of units (SI). Nat. Bur. of Stand. Special Publ. 330,<br />
3rd edn. U.S. Govt. Printing Office, Washington D.C.,<br />
U.S.A.<br />
10. Shibles, R. 1976. Committee Report. Terminology pertaining<br />
to photosynthesis. Crop Sci. 16:437-439.<br />
11. Thimijan, R.W., and R.D. Heins. 1983. Photometric, radio<br />
metric, and <strong>quantum</strong> <strong>li</strong>ght units of measure: a review of<br />
procedures for interconversion. HortScience 18:818-822.<br />
BROCHURE REFERENCES<br />
1. Biggs, W.W., A.R. Edison, J.D. Easton, K.W. Brown,<br />
J.W. Maranville and M.D. Clegg. 1971. Photosynthesis<br />
<strong>li</strong>ght <strong>sensor</strong> and meter. Ecology 52:125-131.<br />
2. De Wit, C. T. 1965. Photosynthesis of leaf canopies. Agric.<br />
Res. Rep. No. 663. Institute for Bio. and Chem. Res. on<br />
Field Crops and Herbage. Wageningen, The Netherlands.<br />
3. Federer, C.A. and C.B. Tanner. 1966. Sensors for<br />
measuring <strong>li</strong>ght available for photosynthesis.<br />
Ecology 47:654-657.<br />
4. Hesketh, J., and D. Baker. 1967. Light and carbon assimilation<br />
by plant communities. Crop Sci. 7:285-293.<br />
5. Flowers, E.C. 1978. Comparison of solar radiation <strong>sensor</strong>s<br />
from various manufacturers. In: 1978 annual report from<br />
NOAA to the DOE.<br />
6. Incoll, L.D., S.P. Long and M.R. Ashmore. 1981. SI units<br />
in pub<strong>li</strong>cations in plant science. In: Commentaries in<br />
Plant Sci. Vol. 2, pp. 83-96, Pergamon, Oxford.<br />
7. Kerr, J.P., G.W. Thurtell and C.B. Tanner. 1967. An integrating<br />
pyranometer for c<strong>li</strong>matological observer stations and<br />
mesoscale networks. J. Appl. Meterol. 6:688-694.<br />
8. Kondratyev, K. Ya. 1969. Direct solar radiation. Radiation<br />
in the atmosphere. Academic Press, New York-London<br />
9. McCree, K.J. 1972. Test of current definitions of photosynthetically<br />
active radiation against leaf photosynthesis<br />
data. Agric. Meteorol. 10:443-453.<br />
10. Monteith, J.L. 1977. C<strong>li</strong>mate and efficiency of crop production<br />
in Britain. Philos. Trans. R. Soc. London, Ser. B.<br />
281:277-294.<br />
11. Palmiter, L.S., L.B. Hamilton, M.J. Holtz. 1979. Low cost<br />
performance evaluation of passive solar buildings. SERI/RR-<br />
63-223. UC-59B.<br />
12. Rabinowitch, E.E. 1951. Photosynthesis and related<br />
processes. Inter-science. New York. 2088 pages.<br />
13. Ritchie, J.T. 1980. C<strong>li</strong>mate and Soil Water. In: Moving up<br />
the yield curve: Advances and obstacles. ASA Spec. Pub.<br />
No. 39:1-23. Stelly, M., L. S. Murphy, L. F. Welch, E. C.<br />
Doll (Ed). Amer. Soc. Agron./Soil Sci. Soc. Amer.<br />
14. Shibles, R. 1976. Committee Report: Terminology<br />
pertaining to photosynthesis. Crop Sci. 16:437-439.<br />
29
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