“…The most widely used photon detector, Cd 0.2 Hg 0.8 Te operating in the 8-12 m atmospheric window, must be cooled to liquid nitrogen temperature, 77 K, for optimum performance. 1 Thermal detectors, on the other hand, usually require single stage cooling around room temperature, although they can operate adequately over a wide range of temperatures. The tradeoff, however, is that the sensitivity of thermal detectors is greatly inferior to that of photon detectors and therefore have ͑so far͒ been limited to applications that do not require extremely high sensitivity or fast response, such as surveillance, fire fighting, and low contrast thermal imaging.…”