Sensors & Accessories
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include a report entitled "Radiation Measurements", which
summarizes the types of measurements that can be made
with each LI-COR sensor and contains conversion factors
for commonly used measurement units. A report concern-
ing the immersion effect and cosine collecting properties of
underwater sensors is also available (Roemer, Hoagland
report. Request Application Note #110).
2.2 Sensor Calibration
All LI-COR radiation sensors produce a current pro-
portional to the radiation intensity. During factory cali-
bration, sensor output (in microamps) is measured while the
sensor is exposed to a standard lamp of known intensity.
The sensor output at this intensity has general units of
microamps per radiation unit and is called the Calibration
Constant (Calconstant). Each sensor has a slightly differ-
ent output at a given radiation intensity and will therefore
have a unique Calconstant.
The LI-250 measures the current output of the sensor in
units of microamps, and converts the measured current to
units of radiation. To make this conversion, the LI-250
uses the sensor Calibration Multiplier. The Calibration
Multiplier is the negative reciprocal of the Calconstant.
Multiplier
Calcons
t
=
−
1
tan
The Calibration Multiplier is always a negative number (be-
cause the shield of the coaxial cable is positive instead of
negative), and is expressed in radiation units per microamp.
