- Infrared detector
An infrared detector is a
photodetectorthat reacts to infrared(IR) radiation. The two main types of detectors are thermal and photonic.
The thermal effects of the incident IR radiation can be followed through many temperature dependent phenomena.
Bolometers and microbolometers are based on changes in resistance. Thermocouples and thermopiles use the thermoelectric effect. Golay cells follow thermal expansion. In IR spectrometers the pyroelectric detectors are the most widespread.
The response time and sensitivity of photonic detectors can be much higher, but usually these have to be cooled to cut
thermal noise. The materials in these are semiconductorswith narrow band gaps. Incident IR photons can cause electronic excitations. In photoconductivedetectors, the resistivityof the detector element is monitored. Photovoltaicdetectors contain a p-n junctionon which photoelectric current appears upon illumination.A few detector materials:
Vanadium pentoxideis frequently used as a detector material in uncooled microbolometerarrays.
* [http://sales.hamamatsu.com/assets/applications/SSD/Characteristics_and_use_of_infrared_detectors.pdf Characteristics and Use of Infrared Detectors] Hamamatsu Photonics
* [http://sales.hamamatsu.com/assets/applications/SSD/irdetectorvariety.pdf Technological Advances Lead to Greater Variety of Infrared Detectors] Hamamatsu Photonics
conclusionTHERMOCOUPLE-Di similar stripes of metals,BOLOMETER- Metal or semiconductor,THERMISTOR-Metallic oxide(not used in open environment),GOLAY CELL - Black metal plates (commercially used)
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