The optimal operating temperature range for Indium Antimonide detectors is typically near 35 Kelvin. Commercially available miniature split-Stirling cycle cryocoolers present an attractive approach to detector cooling. These units offer stand-alone operation, small size, light weight, low power input, low vibration, moderate cost, and reasonable lifetime. However, currently available units have inadequate cooling capacity at 35 Kelvin when operated in a normal manner. We have substantially increased the low temperature cooling capacity of commercial cryocoolers by utilizing the 77 Kelvin intermediate temperature available in liquid nitrogen cooled instruments. We thermally connect the liquid nitrogen cold sink to the middle of the cryocooler coldfinger, shunting heat from the coldfinger to the LN2. The resulting performance improvements and careful thermal design of the detector mount to minimize parasitic heat loads a low miniature split-Stirling cycle cryocoolers to provide adequate cooling of large format Indium Antimonide focal plane arrays.
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