A high performance, medium waveband infrared focal plane array cooled by an intermediate temperature Stirling engine

Conventional photovoltaic infrared detector arrays based on cadmium mercury telluride (CMT) are normally cooled to 77 K in order to achieve high performance. In the medium waveband (3-5 μm) it is not necessary to cool detectors close to 77 K to achieve high performance. The ability to operate at higher temperatures allows the use of low power, high reliability, compact cooling engines based on the Stirling cycle. The authors derive empirically the behaviour of infrared diode characteristics with temperature and cut-off wavelength and predict the operating conditions needed to achieve high performance. Based on these calculations and the measured performance of prototype engines, they suggest a scheme to minimise the size and power of 3-μm subsystems suitable for a range of applications