As a result of verification with five thermometers, the end of the shock is ...
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This is also a multifunctional type that can measure body temperature in about 1 second using an infrared sensor, and can also measure food, drink, and room temperature.
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Infrared sensor(Sekigaisen sensor) is light in the infrared region (Infrared) Is received and converted into an electric signal to extract and apply the necessary information, and equipment that uses that technology.It has features such as being able to see objects without stimulating human vision and being able to instantly measure the temperature of an object from a distance without contact.
Classification by principle
However, modern infrared sensors are basicallyElectronic elementOf expressionPhotodetectorIt is composed of (light receiving elements), and can be divided into two types, a thermal type (uncooled type) and a quantum type (cooled type), depending on its operating principle.
|Operating principle||Detection wavelength||Element material|
|External photoelectric effect||Photocell||UV|
|Internal photoelectric effect||Light conduction型||3-5 µm||Cadmium telluridemercury(HgCdTe)|
|8-12 µm||Cadmium telluridemercury(HgCdTe)|
Gallium arsenide(GaAs) ・ (AlGaAs) Quantum well type infrared detection element (QWIP）
|8-12 µm||Cadmium telluridemercury(HgCdTe)|
|Pyroelectric effect||Pyroelectric element型||1-3 µm||Sulfidelead(PbS)|
|8-12 µm||Barium titanatestrontium(BST)|
Lead zirconate titiate(PZT)
|Thermoelectric effect||thermocouple型||Polycrystalline silicon (Poly-Si)|
|Depends on temperature|
Of electrical resistance
Giant magnetoresistive effect (CMR）
Quantum type (cooling type)
High detection sensitivity, excellent response speed,Thermal type (uncooled type)It has a detection capacity of 100 to 1000 times that of.Sensitivity depends not only on the type of semiconductor used, but also on the wavelength of infrared rays (wavelength dependence).In the case of artificial ones, the difference is several tens of degrees,Pit organHas a thermal field of viewヘ ビEtc. can detect a difference of several degrees.
But on the other hand, in principleThermal noiseIt is necessary to keep the image sensor at a sufficiently low temperature as compared with the subject because it is easily affected by the above and detects the heat generated by the image sensor itself.It is housed in a vacuum-maintained housing and kept at an extremely low temperature.The temperature is usually 60K to 100K (-213 ° C to -173 ° C), depending on the application and required level.It takes time to operate because it needs to be cooled.
As a cooling measure,Joule-Thomson effect,Stirling refrigeratorIs often used.Infrared space telescopeIn the case of, there are some that reach the de facto life when the coolant is lost, and recently, after the loss of the coolant, it is often switched to observation with another observation aircraft.
Thermal type (uncooled type)
A thermal (uncooled) infrared sensor receives infrared rays and uses heat.sensorIs warmed up and the change in electrical properties caused by the rise in element temperature is detected.
Quantum type (cooling type)The sensitivity and response speed are lower than those of the above, but the feature is that the wavelength band is wide and it can be used at room temperature.Thermoelectric effectUsedThermoelectric element(ThermopileSuch),Pyroelectric effectUsedPyroelectric element(PZTSuch),Change in electrical resistance with temperatureUsedBolometerand so on.In addition, the color changes reversibly according to the temperature.Image sensor coated with temperature-sensitive liquid crystal microcapsulesThere is also a method of capturing an infrared image by.
Since it can be used at room temperature and does not require cooling measures, it can be made smaller and lighter, but on the other hand, it is affected by the heat capacity of the element, so the image quality such as resolution, gradation, afterimage, and sensitivity is compared with the cooling type. Inferior to the case.
In the case of an image sensor using a thermal (non-cooling) infrared sensor, nothing can be detected unless there is a difference in the amount of infrared radiation between the heat source and the background.That is, when the temperature difference between the background and the heat source is small, it is difficult to distinguish between the background and the heat source, and when there is no temperature difference, it is not possible to take a picture in principle.Also, although it works at room temperature,Thermal noiseTo improve sensitivity by eliminating the influence ofPeltier elementCooling measures such as, etc. may be introduced.
Classification by shape
Apart from the above classification according to the principle of the light receiving element, it can also be classified according to how these elements are arranged.at first,Photoelectric conversion elementTo be used aloneSingle element typeSensors were the mainstream.But in recent yearsMicrofabrication technologyDue to progressIntegrated circuitDue to the progress ofSolid-state image sensorFocal Plane Array: FPA) Is also increasing.
One-dimensionally arranged on the image sensorLinear typeAnd two-dimensionally arrangedFace typeThere is.The one-dimensional image sensor can be scanned with a mirror, etc.Meteorological satellite,Earth observation satelliteWhen mounted on an artificial satellite such as, scanning is performed by rotating or moving the artificial satellite itself.Generally, a one-dimensional image sensor is higher than a two-dimensional image sensor.resolutionCan be obtained.
Near infrared camera
Sensitive to near infrared raysInfrared film,Image sensorBy using the above, it is possible to shoot an image different from the image that can be seen with the naked eye.For example, because of its long wavelength, compared to visible lightscatteringIt can be used to photograph an object on the other side by penetrating smoke or a thin cloth by taking advantage of its difficult property.Exploiting this featureSwimwearSee throughStealSwimsuits that sell materials that are not transparent to infrared rays are also on sale because of the rampant behavior.Images obtained from near-infrared cameras are usually monochrome images because infrared film and most image sensors have the same structure as monochrome cameras and do not support different wavelengths.
In addition, since infrared rays are invisible, even if the subject is illuminated with a near-infrared light source at night, the subject can be photographed without being noticed.In addition to being used for shooting nocturnal wild animals, it can also be used for crime prevention without stimulating the other party.Due to the deterioration of global security in recent years, CCD and infrared rays have a sensitivity distribution down to near infrared rays.LEDUsing lightingSurveillance cameraHowever, it has been widely used for surveillance cameras in the city, cameras at various tollhouse gates, and doorphones for home use. There is also a light source that can illuminate an object 100 meters away.Even with a military night-vision scope, lights星In addition to the slight amount of visible light emitted from, near-infrared rays are amplified to obtain a clear image.
Infrared cameras are used through an infrared filter that blocks visible light.Infrared light is compared to visible lightガ ラ スSince the refractive index for is small, it is necessary to take a large focal length when shooting.Therefore, somelensSome of them have a mark for focusing with infrared rays after focusing with normal light.
Heat ray imaging device
If you use a video device that detects the far-infrared region,Heat sourceThe object that becomesBiology It is possible to detect and shoot far infrared rays emitted by.Since the subject itself is recognized as a light emitter, it can be recognized even when there is no external light source.Far-infrared rays have a longer wavelength than near-infrared rays, so they have high transparency and are reflected even if the surface of the reflecting surface is slightly rough, but the resolution is extremely low for a video device, and visible light is used when shooting moving images. The afterimage remains longer than that of the camera.By analyzing the intensity of far infrared rays, the temperature distribution is calculated and displayed.Thermography(Thermal image).Usually, the hot part is displayed in red and the low temperature part is displayed in blue.The device that generates thisHeat ray imaging device,Forward monitoring infrared (FLIR) deviceIs a representative.
Infrared search and track device
While FLIR and other heat ray imaging devices capture thermography, the infrared search and track system (IRST) is a device that treats an object as a point target and searches and tracks it.Therefore, although they use the same frequency band, they are different in principle.,AN / AAQ-40 EOTSThere are also systems that can be used by switching between FLIR and IRST as appropriate..
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