an electromagnetic radiation detector whose operation is based on the pyroelectric effect, that is, the temperature dependence of the spontaneous polarization of pyroelectrics. Pyroelectric detectors are classified as thermal radiation detectors. A pyroelectric detector may be considered as a voltage generator whose internal resistance is capacitive. Therefore, the detector is suitable only for recording radiation fluxes of variable intensity.
The sensing element of a pyroelectric detector is a thin sheet of a pyroelectric, such as triglycine sulfite, barium titanate, or lead titanate, with electrodes applied to the surfaces perpendicular to the polar axis. The electrode facing the radiation source has an absorptive coating whose optical properties determine the region of spectral sensitivity of the detector (in the wavelength range from tenths of a micron to several millimeters). The maximum sensitivity of a pyroelectric detector is constant over a broad frequency range, which makes it possible to use the detector at radiation modulation frequencies up to tens of megahertz (other thermal detectors can be used at modulation frequencies up to tens of hertz).
Pyroelectric detectors are used in the study of fast-changing thermal processes, in equipment for spectral research, in remote temperature sensors, and in thermal imaging devices.
I. A. LEVINA