Temperature dependence of spatial noise in InSb focal plane arrays

Performance of InSb focal plane array (FPA) detectors depends to a great extent on both the absolute temperature and the temperature fluctuations of the detector. The residual spatial noise, which can be achieved and maintained after a two-point non-uniformity correction (NUC), increases when the FPA temperature changes relative to that at which the NUC procedure was performed. A model is described, which allows prediction of the InSb FPA residual non-uniformity (RNU) as a function of the FPA temperature fluctuations for a given set of the FPA, cold shield and background radiation parameters. The calculated values are confirmed by experimental data. It is demonstrated that, as predicted, RNU degradation is primarily caused by signal offset changes corresponding to the InSb dark current variations, which are induced by the FPA temperature instability. The influence of the FPA temperature variation on NCTC can be effectively compensated by a one-point offset correction. When this procedure is impractical, the dark current compensation method is proposed, which allows for a real-time, continuous compensation of the FPA temperature variations, resulting in a low residual non-uniformity.