Thermal contrast detected with a quantum detector

We evaluate the thermal contrast detected by a quantum detector in a focal plane of an infrared instrument. The detected thermal contrast is shown to consist of two terms. The term corresponding to the temperature dependence of emissivity, previously neglected, is evaluated and shown to be a significant contributing factor. For the case of a metal mirror as a source of stray Light, ghost images, and narcissus, the error is estimated to be about 20%. The term in the detected contrast associated with the radiative emission is shown to be proportional to temperature to the power of 2, rather than 3, published previously. (C) 1999 Published by Elsevier Science B.V. All rights reserved.