text: In terms of the pyroelectric detector, it can be used as a sensor to support the system. Due to the unipolar axis characteristics of the pyroelectric crystal, it is characterized by asymmetry. Polarization due to changes in temperature, the so-called pyroelectric effect, is currently widely used in sensor technology. Pyroelectric crystals need to be very thin to prepare and are plated in a direction perpendicular to the polar axis. An absorbing layer (blackening layer) is also required on the upper electrode. When this absorbing layer is exposed to infrared radiation, the pyroelectric chip is heated and produces a surface electrode. If the amount of radiation is interrupted, a charge opposite to the direction of polarization is generated. However, this charge is very small, so the charge is converted to a signal voltage by ultra low noise and ultra low leakage field effect transistors (JFET) or operational amplifiers (OpAmp) before neutralized by the internal resistance of the crystal.  Pyroelectric detectors have a high signal-to-noise ratio even at 4K Hz. For example, in a Fourier infrared spectrometer, a thermopile can only perform better at a few hertz.