Response Analysis of Multilayer Pyroelectric Structures

초록

One of the main issues in the development of the multilayered pyroelectric arrays is to obtain high detectivity of the elementary device with small size. Theoretical modeling can give optimum values of parameters which lead to the essential improving of design, operating regimes and as a result, detectivity of the device without a lot of experimental works.In general, there are two main approaches of theoretical modeling in the pyroelectric detectors. One is based on the simple lumped model proposed in the pioneer paper of Cooper. It assumes that all thermal processes in pyroelectric detector can be described by the heat loss thermal conductance and thermal capacitance. This simple lumped model, however, can not predict accurately the characteristics of the multilayered pyroelectric system with nonuniform distribution of temperature. The other approach of modeling is, so called, correct models, based on the diffusion theory. They describe simple structures only or lead to complicated dependence of the signal on the various parameters that makes the analysis of the real system very difficult. n this study, we have employed the lumped effective thermal conductivity approach for the qualitative analysis of the multilayered pyroelectric structures. We have performed the analysis of the diaphragm-type pyroelectric structure that consists of the sensing element fixed on its perimeter at the dielectric substrate with the conic hole in its central part. Our analysis shows that the response of the multilayered pyroelectric system can be described approximately as a sum of specific parts with simple frequency dependencies such as w-1. w-1/2, w0 They correspond to the main types of distribution of heat energy such as the total or partial heating of the sensing element, heating of the boundary regions of surrounding media or intermediate layer and heat flow through the pyroelectric element in the back medium with appropriate effective thermal resistances. The main advantage of