Drift in Cryogenically Cooled Photodetectors: Causes and Cures
Cryogenically cooled detectors exhibit drifts in their output with time. Users should select Dewars with metal O-rings whenever possible and should evacuate and bake the Dewars periodically.
Infrared photodetectors benefit greatly from cooling to cryogenic temperatures. For this reason, manufacturers mount the majority of these instruments in evacuated Dewars that use cryogenic coolants such as liquid nitrogen or helium.
Laboratories around the world employ these detectors. Until recently, however, nobody reported that their output (spectral responsivity) drifts significantly with time after cooling. Drift of many percent per minute occurs, making the validity of the data acquired with such detectors suspect...
The complete article appears in the April 2006 issue of Photonics Spectra. If you do not have a copy of this issue,
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