Campbell Scientific LI190SB LI-COR Quantum Sensor - Manual (Page 5)

LI190SB Quantum Sensor
1. General Description
The LI190SB quantum sensor measures photosynthetically active radiation
(PAR) in the 400 to 700 nm waveband. The unit of measurement is µmoles
per second per square meter (µmol s
-1 m -2 ).
The quantum sensor is designed to measure PAR received on a plane surface.
The indicated sensor response (Figure 1-1) is selected because it approximates
the photosynthetic response of plants for which data are available. A silicon
photodiode with an enhanced response in the visible wavelengths is used as the
sensor. A visible bandpass interference filter in combination with colored
glass filters is mounted in a cosine corrected head.
Measuring PAR within plant canopies, greenhouses, controlled environment
chambers, confined laboratory conditions, or at remote environmental
monitoring sites are all typical applications for this sensor.
During the night the LI190SB may output a slightly negative value, caused by
RF noise. Negative values may be set to zero in the datalogger program.
A Calibration Certificate is shipped with each sensor that includes a serial
number and calibration constant. The calibration constant is unique for each
sensor, and is used to compute the multiplier for the measurement instruction
in the datalogger program.
FIGURE 1-1. LI190SB Spectral Response
1