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Infrared sensor work principle

Infrared technology developing until now, already has been known to everyone,

this technology has been generally used in the application of modern science

technology, national defense and industrial and agricultural fields.

Infrared sensor system is by means of media to be a infrared measurement system.

for the media, in accordance with the function can be divided into five categories:

(1) radiometer, apply to spectrum and radiation measurements; (2) search and track

system, for searching and tracking Infrared target to define its spatial location as

well as tracking its movement; (3) thermal imaging systems, can generate the

distribution chart of the target infrared radiation; (4) infrared distance measurement

and Communication systems; (5) hybrid system, is of the combination of two or

more systems above mentioned.

According to detection mechanism, Infrared sensors can be divided: photon

detectors(based on the photoelectric effect) and heat detectors(based on thermal

effects.)

We first look at the composition of infrared systems, the main optical system and

auxiliary optical system, on the basis of that we discuss the key components of IR

in detail. In fact, the infrared sensor Works is not complicated.

Infrared sensor work principle

(1) measured target. infrared radiation infrared system can be set according to the

peculiarity of IR radiation of measured target.

(2) atmosphere attenuation. infrared radiation of measured target will be attenuated

through the Earths atmosphere, due to the scattering and absorption of gas

molecules, a variety of gases and sol particles.

(3) optical receiver. It receives some infrared radiation of measured target and

transmittes to the infrared sensor. just like radar antenna.

(4) radiation modulator. it can modulates radiation into alternating radiation,

providing information of target location and filtering out a large area of

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interference information. It known as the modulation drive or chopper, which has

variety of structures.

(5) infrared detector. This is the core of IR systems. It is the use of the physical

effects of interaction between infrared radiation and matter to detect infraredradiation. In most of cases it is the use of this electrical effects showing in the

interaction effect. Such detectors can be divided into sensitive photon detectors and

thermal detectors.

(6) detector cooler. Because some detectors must work at low temperature. By

refrigeration, the equipment can shorten response time to enhance sensitivity.

(7) signal processing system. It could enlarge and tilter detecting signal to get

information. And then translates the information into required format which istransfer to the control device or display at last.

(8) display device. This is the final device of infrared device. Display devices are

commonly used including oscilloscopes, cathode ray tubes, infrared-sensitive

materials, instructions and other instruments and recorder.

Infrared system could be able to complete the relevant physical measurement in

accordance with the process above mentioned.

The core of infrared system is infrared detectors which can be divided into

Thermal detectors and photon detectors according to the different detecting

mechanism. The following example of a thermal detector is used to analyze

principle of the detector.

Thermal detectors make use of radiant heat effect, so that make the temperature of

detecting component raise after receiving radiation energy, and thus make the

detector performance depends on the temperature performance change. Theradiation will be detected when detecting temperature performance change. In most

cases, to detect change through thermal radiation. When the device receives

radiation to cause non-electricity change that can be measured the power change

by means of appropriate transformation.