LI-190 Quantum SensorMeasure Photosynthetically Active Radiation
Accurate measurements are obtained under all natural and artificial lighting conditions because of the computer-tailored spectral response of the LI-190. Colored glass filters are used to tailor the silicon photodiode response to the desired quantum response. An interference filter provides a sharp cutoff at 700 nm, which is critical for measurements under vegetation where the ratio of infrared to visible light may be high. A small response in the infrared region can cause an appreciable measurement error. This sensor, developed from earlier work (1), was pioneered by LI-COR and has become the standard for PPFD measurement in most photosynthesis-related studies. The LI-190 is also used in oceanography, limnology, and marine science as a reference sensor for comparison to underwater PAR measured by the LI-192 Underwater Quantum Sensor and LI-193 Spherical Underwater Quantum Sensor.
References1. Biggs, W.W., A.R. Edison, J.D. Easton, K.W. Brown, J.W. Maranville and M.D. Clegg. 1971. Photosynthesis light sensor and meter. Ecology 52:125-131. 2. Federer, C.A. and C.B. Tanner. 1966. Sensors for measuring light available for photosynthesis. Ecology 47:654-657. 3. McCree, K.J. 1972. Test of current definitions of photosynthetically active radiation against leaf photosynthesis data. Agric. Meteorol. 10:443-453. Absolute Calibration: ± 5% traceable to the National Institute of Standards and Technology (NIST). Sensitivity: Typical 5µA per 1000 µmol s-1 m-2. Linearity: Maximum deviation of 1% up to 10,000 µmol s-1 m-2. Stability: Typically < ± 2% change over a 1 year period. Response Time: 10 µs. Temperature Dependence: 0.15% per °C maximum. Cosine Correction: Cosine corrected up to 80° angle of incidence. Azimuth: < ± 1% error over 360° at 45° elevation. Tilt: No error induced from orientation. Operating Temperature: -40 to 65 °C. Relative Humidity: 0 to 100%. Detector: High stability silicon photovoltaic detector (blue enhanced). Sensor Housing: Weatherproof anodized aluminum case with acrylic diffuser and stainless steel hardware. Size: 2.38 cm Dia. x 2.54 cm H (0.94” x 1.0”). Weight: 28 g (1 oz). Cable Length: 3.0 m (10 ft). There are three different terminations available for the LI-190 Quantum Sensor: The LI-190SA Quantum Sensor has a cable that terminates with a BNC connector. This allows for easy and direct connection to the LI-250A Light Meter or LI-1400 DataLogger. The LI-190SZ Quantum Sensor terminates with bare leads (no connector). It can be connected to a data acquisition device or datalogger that measures millivolts when a 604 Ohm shunt resistor is used. As an alternative, the 2290 Millivolt Adapter can be purchased with the LI-190SA. The 2290 Millivolt Adapter uses a 604 Ohm precision resistor to convert the LI-190 output from microamps to millivolts. The LI-190SL is an LI-190SA and a standardized output millivolt adapter. The LI-190SL produces a standardized 10 mv/2000 µmol s-1 m-2 output that eliminates the need to change calibration constants or multipliers when type SL sensors are exchanged in the field. The LI-190 Quantum Sensor comes with a standard 10 feet (approximately 3 m) of cable. You may also order the LI-190 with 50 feet (approximately 15 m) of cable using the LI-190SA-50, LI-190SZ-50 or LI-190SL-50 part numbers. 50-foot and 100-foot extension cables are also available. The 2003S Mounting and Leveling Fixture is recommended for each sensor unless other provisions for mounting are made. Other accessories are described on the Accessories Page. LI-190SA Quantum Sensor (with BNC connector) LI-190SZ Quantum Sensor (with bare leads) LI-190SL Quantum Sensor (LI-190SA and standardized millivolt adapter) LI-190SA-50 Quantum Sensor (with BNC connector) LI-190SZ-50 Quantum Sensor (with bare leads) LI-190SL-50 Quantum Sensor (LI-190SA-50 and standardized millivolt adapter) 2290 Millivolt Adapter (used with the LI-190SA) 2003S Mounting and Leveling Fixture 2222SB-50 Extension Cable (50 ft) for the LI-190SA or LI-190SL 2222SB-100 Extension Cable (100 ft) for the LI-190SA or LI-190SL
Additional literature related to the LI-190 is also available:
If you have any questions about the LI-190 please feel free to contact us and discuss with our Applications Analysts and Scientists (or your local LI-COR Distributor) how the LI-190 can help you with your research. Selected Links
Please submit your published papers or links to your websites to be featured here by contacting the Product Manager, Mr. Brent Claassen. Journal ReferencesUse the academic search engines below to find references to the LI-190 in many peer reviewed scientific publications. For best results, start with the search terms provided below or use the forms to customize a search. Results open in a new window. References from HighWire Press - Internet Imprint of the Stanford University Libraries
References from Google Scholar™Common Internet searches can be performed with Google, and many articles can be found with Google Scholar: The LI-190 includes a printed copy of the Instruction Manual. You can download future updates of the LI-190 manual on this page.
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During
photosynthesis, plants use energy in the region of the
electromagnetic spectrum from 400-700 nm. The radiation
in this range, referred to as Photosynthetically Active
Radiation (PAR), is typically measured as Photosynthetic Photon Flux Density
(PPFD), which has units of quanta (photons) per unit
time per unit surface area. The units most commonly used
are micromoles of quanta per second per square meter
(mmol s-1 m-2). Plant scientists, horticulturists,
ecologists, and other environmental scientists use the
LI-190 Quantum Sensor to accurately measure this variable.
