How does a pyroelectric detector work?
When light radiation (UV, VIS, IR, THz) is applied to a thin pyroelectric crystal (<40m) its temperature increases by fractions of a degree centigrade. Turning on the radiation an electrical charge is generated by heating, turning off the light the crystal cools down and an opposite charge is generated. These very small electrical charges are generally converted within the detector housing to convenient signal voltages by use of extremely low noise and low leakage Field Effect Transistors (JFET) or CMOS operational amplifiers (OpAmp). It is very important to remember that only modulated radiation creates a signal, therefore either pulsed or mechanically chopped IR sources are used and unmodulated disturbing background radiation is filtered out.
