Sensitivity of pyroelectric IR-detectors of slow thermal processes, especially of human body sensors, depends strongly on their response in the infra-low (/spl sim/0.1 to 1 Hz) region of frequency spectrum. The main mechanisms of heat losses-heat conduction of environment, lateral heat conduction in the plane of sensitive element, and emission of radiation-are considered. Their influence on the low-frequency response of pyroelectric sensors is estimated. Exact solutions and simple expressions for quantitative description of main specific features of real systems are obtained. Criteria of validity of the adequate models are determined.
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