Analysis of response of pyroelectric optical detectors

Abstract

Several configurations of pyroelectric optical-radiation detectors are mathematically modeled to determine their frequency response and current response to step-function heat inputs. Included in the analysis are heat losses by conduction and reradiation, effects of absorptive coatings, and an experimentally observed nonuniformity of polarization through the thickness of polymer pyroelectric films. Roll-off of the frequency response at both low and high frequencies is carefully examined. Curve fitting to response data allows a quantitative determination of the pyroelectric coefficient and the degree of nonuniformity of the polarization. The thermal conductivities of gold blacks used as absorbers are determined from the high-frequency data together with independent measurements of the black thicknesses and densities. The total emissivity of evaporated nickel films sometimes used as absorbers can be estimated from the low-frequency data. The difference in response to optical and electrical heat inputs is examined as a part of our effort in fabricating electrically self-calibrating optical detectors.