NOTICE The information contained in this document is subject to change without notice. LI-COR MAKES NO WARRANTY OF ANY KIND WITH REGARD TO THIS MATERIAL, INCLUDING, BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. LI-COR shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing, performance, or use of this material.
Section I General Information Type "SA" Sensors LI-COR SA type sensors are characterized by having the coaxial sensor cable terminated with a BNC connector. Figure 1 shows a typical SA type sensor. Type SA terrestrial sensors include the LI-190SA Quantum Sensor, the LI-191SA Line Quantum Sensor, the LI-200SA Pyranometer Sensor, and the LI-210SA Photometric sensor.
LI-185A, LI-188, LI-510, and LI-550 require the use of the 9901-014 connector conversion cable. Contact LI-COR for further details. When a LI-COR Light Meter or data logger is not used, the sensors can be used with other millivolt recorders or data loggers by connecting a millivolt adapter.
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1000 mol s m Or, = 4.83 mV/1000 µmol s The shield of the coaxial cable on LI-COR light sensors is positive and the center conductor is negative. (The trans-impedance amplifier used in LI-COR light meters requires a negative signal). For data logger or...
Figure 2. Lambert's Cosine Law. Cosine Correction Properties Cosine corrected LI-COR terrestrial type sensors are all designed for the same cosine response characteristics. The percent of true cosine response is presented in Figure 3. The error is typically less than ± 5% for angles less than 80°...
DO NOT use alcohol, organic solvents, abrasives, or strong detergents to clean the diffusor element on LI-COR light sensors. The acrylic material used in LI-COR light sensors can be crazed by exposure to alcohol or organic solvents, which will adversely affect the cosine response of the sensor.
The vertical edge of the diffuser must be kept clean in order to maintain appropriate cosine correction. LI-190SA Spectral Response In 1976, LI-COR had sensor calibration data verified by the National Research Council of Canada (NRC), one of the major standards laboratories in the world.
Figure 4. LI-190SA Sensor Response Curve. The spectral response of the quantum sensor is obtained by use of a light source and a monochromator. A thermopile or calibrated silicon photodiode which has a known spectral response over the spectral range of interest is used to determine the monochromator output in energy flux density, W(λ), at the wavelength setting λ.
The NRC performed an absolute calibration of the LI-COR Quantum Sensor. Information concerning these tests is available from LI-COR. The calibration is obtained at LI-COR by using a standard light source calibrated against a National Bureau of Standards lamp. The photon flux density from the standardized lamp is known in terms of micromoles s where one micromole = 6.022 x 10...
LI-190SA Specifications Absolute Calibration: ± 5% traceable to the U.S. National Institute of Standards and Technology (NIST). Sensitivity: Typically 8 µA per 1000 µmol s Linearity: Maximum deviation of 1% up to 10,000 µmol s Stability: < ± 2% change over a 1 year period. Response Time: 10 µs.
Spectral Pyranometer (PSP) of which the calibration is periodically confirmed. The calibration was performed under daylight conditions by a computer sampling of instantaneous readings from the Eppley and LI-COR pyranometers. Instantaneous readings were taken continuously for 10 minutes and then averaged. Sequential ten minute averaging periods were run from sunup to sundown for 3-4 days.
LI-200SA Specifications Calibration: Calibrated against an Eppley Precision Spectral Pyranometer (PSP) under natural daylight conditions. Absolute error under these conditions is ± 5% maximum, typically ± 3%. Sensitivity: Typically 80 µA per 1000 W m Linearity: Maximum deviation of 1% up to 3000 W m Stability: <...
LI-210SA Photometric Sensor Use of the Photometric Sensor The LI-210SA Photometric Sensor is designed to measure illumination in terms of lux (1 footcandle = 10.764 lux). This is radiation as the human eye sees it. The spectral response is shown in Figure 6.
Photometric Terms Although characteristics of the human eye vary from person to person, standard luminosity coefficients for the eye were defined by the Commission Internationale de Eclairage (C.I.E., International Commission on Illumination) in 1931. An absolute "sensitivity" figure established for the standard eye relates photometric units and radiant power units.
A footcandle is one candela at a distance of one foot. Spectral Response The spectral response of a typical LI-COR LI-210SA Photometric Sensor compared to the C.I.E. standard observer curve is presented in Figure 6. In...
Beginning June 1, 1978, all LI-COR photometric sensors have been calibrated using 683 lumens per watt as the value of spectral luminous efficacy at a wavelength of 555 nm, rather than the previously accepted C.I.E. standard value of 680 lumens per watt.
LI-191SA Line Quantum Sensor Use of the Line Quantum Sensor The LI-191SA Sensor is designed for measuring PAR (photosynthetically active radiation) in applications where the radiation to be measured is spatially non-uniform (such as within plant canopies). To achieve this, the sensor features a sensing area that is one meter in length.
Spectral Response The spectral response of the LI-191SA is comparable to that of the LI-190SA Quantum Sensor. All LI-COR quantum sensors use computer tailored filter glasses to achieve a response that closely approximates the desired ideal quantum response. See Figure 4.
Figure 7. Cosine Response of LI-191SA Line Quantum Sensor Measurement of the spectral response requires a stabilized light source, monochromator, lock-in amplifier and calibrated reference detector. Measurements taken with the test sensor and reference detector at many wavelengths yield data points used to plot the relative spectral response. Absolute Calibration The uncertainty of the calibration is ±...
LI-191SA Specifications Absolute Calibration: ± 10% traceable to NIST. The LI-191SA is calibrated via transfer calibration using a reference LI-190SA Quantum Sensor. Transfer error is ± 5% (included in the ± 10%). Sensitivity: Typically 3 µA per 1000 µmol s Linearity: Maximum deviation of 1% up to 10,000 µmol s Stability: <...
Accessories 2003S Mounting and Leveling Fixture. The 2003S is for use with all LI-COR terrestrial type sensors (2.38 cm Dia.). The base is anodized aluminum with stainless steel leveling screws and a weatherproof spirit level for leveling the sensors during operation.
Warranty Each LI-COR, inc. instrument is warranted by LI-COR, inc. to be free from defects in material and workmanship; however, LI-COR, inc.'s sole obligation under this warranty shall be to repair or replace any part of the instrument which LI-COR, inc.'s examination discloses to have been...
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LI-COR, inc.'s authorized distributor, whichever is earlier.
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® 4421 Superior Street P.O. Box 4425 Lincoln, Nebraska 68504 USA Phone: 402-467-3576 FAX: 402-467-2819 Toll-free 1-800-447-3576 (U.S. & Canada) E-mail: envsales@env.licor.com Internet: http://www.licor.com...
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