Classification of infrared sensors

The infrared sensor includes an optical system, a detection element and a conversion circuit. According to different structures, optical systems can be divided into two types: transmissive and reflective. The detection element can be divided into thermal detection element and photoelectric detection element according to the working principle. The most commonly used thermal element is thermistor. When the thermistor is exposed to infrared radiation, the temperature rises and the resistance changes (this change may be larger or smaller, because thermistors can be divided into positive temperature coefficient thermistors and negative temperature coefficient thermistors), It becomes an electrical signal output through the conversion circuit. Photoelectric detection elements are commonly used photosensitive elements, usually made of lead sulfide, lead selenide, indium arsenide, antimony arsenide, mercury cadmium telluride ternary alloy, germanium and silicon doped materials.