Thermal modulation transfer function analysis of pyroelectric device characteristics

The performance characteristics, such as responsivity and spatial resolution, of pyroelectric devices, are calculated by employing a two-dimensional thermal modulation transfer function. The thermal analysis is done for the use of a freely suspended wafer of pyroelectric material, a situation encountered in monolithic detector arrays and pyroelectric vidicon targets. Measurements of the frequency dependence of the voltage responsivity and thermal crosstalk from detector elements, fabricated on LiTaO(3) wafers, are found to be in excellent agreement with the theoretical calculations. It is concluded that for linearly scanned arrays, a minimum scanning velocity, nu(min) = (2pikappa)/a, where kappa is the material diffusivity and 2a the dimension of square array element, is desirable for good resolution in the scanning direction and acceptable levels of crosstalk between elements. The analysis also indicates that operation of pyroelectric vidicons in the chopping mode rather than the panning mode provides for better image quality.