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In the infrared imaging system, the infrared detector acts as a radiant energy receiver. Through its photoelectric conversion, the received radiant energy is converted into an electrical signal, and then the electrical signal is amplified and processed to form an image. The infrared detector is the core component of the infrared imaging system.

There are two types of infrared detectors: thermal detectors and photon detectors.

Infrared detectors, such as thermistors, thermocouples, pyroelectric detectors, etc. After this type of detector absorbs infrared radiation, the temperature of the sensitive element rises, causing changes in physical parameters related to temperature.

A photon detector is a detector that completes photoelectric conversion through the interaction of photons with electrons in the material to produce changes in the energy state of the electrons.

At present, in thermal imaging systems, photon detectors are mainly used because they are superior to thermal detectors in terms of response sensitivity or response speed. Photon detectors are divided into two categories: photoconductive and photovoltaic.

Photoconductive detectors work by utilizing the photoelectric effect of semiconductors. The so-called photoconductive effect is that after the semiconductor absorbs the photon energy, non-equilibrium carriers (free electrons or holes) are generated. These carriers participate in conduction, increasing the conductivity of the semiconductor. Since both intrinsic and extrinsic semiconductors can produce photoelectric effects, photoconductive detectors are divided into intrinsic and extrinsic types.

Photovoltaic detectors work by using the photovoltaic effect of semiconductors, that is, a PN junction is formed on an extrinsic semiconductor, electron-hole pairs are generated under the action of incident photons, and the electric field between the junctions separates the two types of carriers to generate electromotive force. .