  Flux dependent non-linearity (reciprocity failure) in HgCdTe NIR detectors
with 1.7 micron cut-off was investigated. A dedicated test station was designed
and built to measure reciprocity failure over the full dynamic range of near
infrared detectors. For flux levels between 1 and 100,000 photons/sec a
limiting sensitivity to reciprocity failure of 0.3%/decade was achieved. First
measurements on several engineering grade 1.7 micron cut-off HgCdTe detectors
show a wide range of reciprocity failure, from less than 0.5%/decade to about
10%/decade. For at least two of the tested detectors, significant spatial
variation in the effect was observed. No indication for wavelength dependency
was found. The origin of reciprocity failure is currently not well understood.
In this paper we present details of our experimental set-up and show the
results of measurements for several detectors.
