Thermal response of some pyroelectric imaging systems

Abstract

For an incident radiation pattern corresponding to one spatial Fourier component of an image the thermal response of the following types of pyroelectric imaging systems is analyzed: the pyroelectric vidicon (operating in the panning mode); the scanned linear array; and the circularly scanned array. Expressions are then obtained for the magnitude of the pyroelectric charge developed as a function of spatial frequency in the image, and these represent thermal modulation transfer functions for the systems. On the basis of these results two particular theoretical comparisons are made between alternative forms of pyroelectric imaging system. The first comparison is between the chopping and panning modes of operation for the pyroelectric vidicon. from which it is found that the panning mode should be capable of giving better performance than chopping, although in practice they may be evenly balanced. The second comparison is between linear and circular scanning systems (both using the same one-dimensional detector array). From this it is concluded that the circular scanning system, which should be simpler to implement in practice, should give performance competitive with the linear scanned array for certain applications.