Two-dimensional analysis of microbolometer arrays

Abstract

A two-dimensional, time-dependent analysis is made of array-compatible bolometers directly deposited onto a single substrate. It applies both to antenna-coupled and surface-absorbing configurations. Unlike previous spherically symmetric treatments, it allows analysis of thermal crosstalk between closely neighboring detectors, and of the effects of finite substrate thickness. In a closely packed array of surface-absorbing detectors, thermal crosstalk generally degrades the array’s resolution more severely than optical (diffractive) crosstalk. Diffraction-limited resolution with surface-absorbing detectors is possible only by sacrificing either thermal resistance, and therefore sensitivity, or filling factor. With a minimum substrate thickness of Lmin, a closely packed, diffraction-limited array is limited to a thermal resistance of Zt≤0.08(κLmin)−1, where κ is the thermal conductivity of the substrate. An array of antenna-coupled bolometers is not subject to this limitation since the thermally and optically sensitive areas need not be equal.