Calibration overview data are listed in box in upper, left-hand corner; sensor specific calibration
coefficients are listed in box in upper, right-hand corner; temperature errors are shown in graph; and
calibration date is listed below descriptions of calibration procedure and traceability.
Sensor Calibration
Apogee SIL-111 infrared radiometers are calibrated in a temperature-controlled chamber that houses a custom-
built blackbody cone (target) for the radiation source. During calibration, infrared radiometers (detectors) are held
in a fixture at the opening of the blackbody cone but are thermally insulated from the cone. Detector and target
temperature are controlled independently. At each calibration set point, detectors are held at a constant
temperature while the blackbody cone is controlled at temperatures below (10 C), above (10 C), and equal to the
detector temperature. The detector temperatures are 10, 25, and 40. Data are collected at each detector
temperature set point, after detectors and target reach constant temperatures.
All Apogee SIL-111 analog infrared radiometers have sensor-specific calibration coefficients determined during the
custom calibration process. Unique coefficients for each sensor are provided on a coefficient certificate (example
shown below).
