Prediction of cryogenic temperature impact on the performance of space-borne IR sensors

The sensitivity of a sensor system and its optical aperture size are two key parameters commonly used to characterize the performance of a remote sensing or space-borne surveillance system. In this work, a sensitivity model for space-borne staring IR sensor systems which are mainly used for point-source detection and identification is developed. Different noise components, including the photon noise from background radiation and near-field thermal radiation of optics, the electronic noise of sensors, as well as the nonuniformity noise of an infrared focal plane array (FPA), are considered. Based on the published parameters of the Multispectral Thermal Imager (MTI) electro-optic sensor system, the feasibility and validity of the model are demonstrated, with emphasis on the prediction of the cryogenic temperature impact on the sensor sensitivity and the optical aperture size requirement in a space-borne multispectral infrared (IR) system.