Infrared detector
An infrared detector is a photodetector that 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 semiconductors with narrow band gaps. Incident IR photons can cause electronic excitations. In photoconductive detectors, the resistivity of the detector element is monitored. Photovoltaic detectors contain a p-n junction on which photoelectric current appears upon illumination.
A few detector materials:
Types
| Type | Spectral range (μm) |
| Indium gallium arsenide (InGaAs) photodiodes | 0.7-2.6 |
| Germanium photodiodes | 0.8-1.7 |
| Lead sulfide (PbS) photoconductive detectors | 1-3.2 |
| Lead selenide (PbSe) photoconductive detectors | 1.5-5.2 |
| Indium arsenide (InAs) photovoltaic detectors | 1-3.8 |
| Platinum silicide (PtSi) photovoltaic detectors | 1-5 |
| Indium antimonide (InSb) photoconductive detectors | 1-6.7 |
| Indium antimonide (InSb) photodiode detectors | 1-5.5 |
| Mercury cadmium telluride (MCT, HgCdTe) photoconductive detectors | 0.8-25 |
| Mercury zinc telluride (MZT, HgZnTe) photoconductive detectors | ? |
Vanadium pentoxide is frequently used as a detector material in uncooled microbolometer arrays.
External links
- Characteristics and Use of Infrared Detectors Hamamatsu Photonics
- Technological Advances Lead to Greater Variety of Infrared Detectors Hamamatsu Photonics
he:גלאי אינפרא אדום פסיבי ko:적외선 검출기 it:Rivelatore ad infrarossi conclusion THERMOCOUPLE-Di similar stripes of metals, BOLOMETER- Metal or semiconductor, THERMISTOR-Metallic oxide(not used in open environment), GOLAY CELL - Black metal plates (commercially used)