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Thermoelectric thermal reference sources (TTRS) for calibration of infrared detectors and systems

The increasing use of the next generation focal plane array infrared detectors has resulted in a growth in the number and types of Thermoelectric Thermal Reference Sources (TTRS). These TTRSs provide a temperature controllable radiometrically uniform, high emissivity surface. When viewed by the system detectors, the TTRS allows the system electronics to perform gain and offset calibration as well as DC restoration. Until now little has been published to aid design engineers trying to incorporate TTRSs into infrared systems. This paper describes the optical, system, electrical, and mechanical parameters of TTRSs. It provides infrared system design engineers with an overview of the critical TTRS parameters as an aid during their design process. TTRSs for scanning and starring arrays are addressed as well as hermetically sealed versus unsealed units. Examples are provided of currently available TTRSs. A discussion of the advantages and disadvantages of hermetically sealed TTRSs as compared to unsealed units is included. The critical parameters of available TTRSs are also discussed.