Frequency response of multilayer pyroelectric sensors

The pyroelectric response of the multilayer system consisting of the front surroundings, the pyroelectric element, the intermediate layer, and the back surroundings is calculated. The general expression and simple relations are obtained between main geometric and thermophysical parameters of the system under consideration and characteristics of the pyroelectric response in a large variety of configurations of pyroelectric sensors, such as detectors with the pyroelectric element in a gas, detectors without air gap as well as detectors with air gap between the element and the substrate, and detectors in immersion systems, etc. In particular, it is shown that, for the detectors with air gap, the wide flat part of the frequency response appears with any properties of substrate if the double thermal resistance of the air gap exceed that of the pyroelectric element, whereas for the detectors without air gap it appears only if the substrate has relatively large complex thermal conductivity.