<title>Miniature integrated dewar/cooler assembly</title>

Abstract

Closed cycle Stirling coolers used in conjunction with infrared detectors operating at or near 80 Kelvin have undergone many design changes over the past several years. The need for increased lifetime and reliability as well as miniaturization for compact imagers has led to the Integrated Dewar Cooler Assembly (IDCA). In the IDCA, the detector is directly mounted to the cooler expander (cold finger) thus eliminating thermal losses from the dewar inner bore and interface losses associated with the use of fuzz buttons and bellows. The result is a significant reduction in thermal inertia (less mass to cool) and heat load (amount of heat to be removed from the system). These reductions have a direct impact on input power demands which indirectly influence the coolers size and weight. Design features such as all metal, ceramic coated clearance seals, isolation of the motor and electionics from the working gas volume and specially designed, long life bearings contribute to increased lifetime. Reliability and lifetime testing on three IDCA units is in progress and to date each unit has demonstxated greater than 5000 hours of operation without failure. IDCA integration and performance testing with discrete detectors and small HgCdTe arrays has been highly successful. The Kollmorgen MICRO-FUR® thermal imager incorporates the IDCA in systems requiring closed cycle cooling. Future plans call for IDCAIFPA integration (HgCdTe, InSb, PtSi) and subsequent performance testing at the system level.