Section 2.
5
Overview of compatible sensors
The LI-250A is compatible with all LI-COR radiation
sensors that have a BNC connector (e.g., LI-200R-BNC or
older LI-200SA sensors). It is important that the LI-250A
be properly configured for the specific sensor used. A
quantum sensor measures photosynthetically active radi-
ation (µmol s
-1
m
-2
of PAR), a pyranometer measures solar
radiation (W m
-2
), and a photometric sensor measures illu-
minance (lux). It is not possible for a pyranometer to read
out in units of lux. If you want the LI-250A to display
units of lux, you must use the photometric sensor.
Recalibration of all LI-COR radiation sensors is recom-
mended every two years. The LI-250A does not need to be
recalibrated.
Overview of radiation sensor calibration
All LI-COR radiation sensors produce a current pro-
portional to the radiation intensity. During factory cal-
ibration, sensor output (in microamps) is measured while
the sensor is exposed to a standard lamp of known intens-
ity. The sensor output at this intensity has general units of
microamps per radiation unit and is called the
Calibration
