What Is a Passive Infrared Detector?
A passive infrared detector is a device that senses far-infrared radiation.
The detector itself does not emit infrared radiation but receives and detects the infrared radiation emitted from the surfaces of objects, such as the human body. It is widely used as a motion sensor in various applications. It detects the emission of infrared radiation from people or animals and is used to control lights, alarms, security systems, and more accordingly.
The main types include bolometric types, which measure changes in the thermal energy generated by infrared radiation to detect temperature changes; pyroelectric types, which utilize pyroelectric materials generating electricity based on thermal energy; and Faraday effect types, which detect changes caused by infrared radiation in a magnetic field.