Infrared

IRnear-infraredinfra-redinfrared radiationnear infraredinfrared lightmid-infraredinfrared spectruminfrared-wavelengthNIR
Infrared radiation (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with longer wavelengths than those of visible light, and is therefore generally invisible to the human eye, although IR at wavelengths up to 1050 nanometers (nm)s from specially pulsed lasers can be seen by humans under certain conditions.wikipedia
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Electromagnetic radiation

electromagnetic waveelectromagnetic waveselectromagnetic
Infrared radiation (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with longer wavelengths than those of visible light, and is therefore generally invisible to the human eye, although IR at wavelengths up to 1050 nanometers (nm)s from specially pulsed lasers can be seen by humans under certain conditions.
It includes radio waves, microwaves, infrared, (visible) light, ultraviolet, X-rays, and gamma rays.

Infrared spectroscopy

infraredinfrared spectrometervibrational spectroscopy
Infrared radiation is emitted or absorbed by molecules when they change their rotational-vibrational movements. Infrared vibrational spectroscopy (see also near-infrared spectroscopy) is a technique that can be used to identify molecules by analysis of their constituent bonds.
Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) involves the interaction of infrared radiation with matter.

William Herschel

HerschelWilliamSir William Herschel
Infrared radiation was discovered in 1800 by astronomer Sir William Herschel, who discovered a type of invisible radiation in the spectrum lower in energy than red light, by means of its effect on a thermometer.
In addition, Herschel discovered infrared radiation.

Infrared astronomy

infraredinfrared radiationJ, H, and K s bands
Infrared astronomy uses sensor-equipped telescopes to penetrate dusty regions of space such as molecular clouds, detect objects such as planets, and to view highly red-shifted objects from the early days of the universe.
Infrared astronomy is the branch of astronomy and astrophysics that studies astronomical objects visible in infrared (IR) radiation.

Visible spectrum

visiblevisible lightspectrum
IR wavelengths extend from the nominal red edge of the visible spectrum at 700 nanometers (frequency 430 THz), to 1 millimeter (300 GHz). mid- and far-infrared are progressively further from the visible spectrum.
The near infrared (NIR) window lies just out of the human vision, as well as the medium wavelength infrared (MWIR) window, and the long wavelength or far infrared (LWIR or FIR) window, although other animals may experience them.

Wave

wavestravelling wavetraveling wave
As with all EMR, IR carries radiant energy and behaves both like a wave and like its quantum particle, the photon.
These types vary in wavelength, and include radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.

Electromagnetic spectrum

spectrumspectrawhite light
Below infrared is the microwave portion of the electromagnetic spectrum.
This frequency range is divided into separate bands, and the electromagnetic waves within each frequency band are called by different names; beginning at the low frequency (long wavelength) end of the spectrum these are: radio waves, microwaves, terahertz waves, infrared, visible light, ultraviolet, X-rays, and gamma rays at the high-frequency (short wavelength) end.

Light

visible lightvisiblelight source
Infrared radiation (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with longer wavelengths than those of visible light, and is therefore generally invisible to the human eye, although IR at wavelengths up to 1050 nanometers (nm)s from specially pulsed lasers can be seen by humans under certain conditions. Of this energy, 527 watts is infrared radiation, 445 watts is visible light, and 32 watts is ultraviolet radiation.
Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), or 4.00 × 10 −7 to 7.00 × 10 −7 m, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths).

Radio wave

radio wavesradioradio signal
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light.

Night vision

night-visionthermal sightnight vision telescope
Extensive uses for military and civilian applications include target acquisition, surveillance, night vision, homing, and tracking.
Enhanced spectral range allows the viewer to take advantage of non-visible sources of electromagnetic radiation (such as near-infrared or ultraviolet radiation).

Ultraviolet

ultraviolet lightUVultraviolet radiation
Of this energy, 527 watts is infrared radiation, 445 watts is visible light, and 32 watts is ultraviolet radiation.
He called them "oxidizing rays" to emphasize chemical reactivity and to distinguish them from "heat rays", discovered the previous year at the other end of the visible spectrum.

Near-infrared spectroscopy

near infrared spectroscopyNIRSnear-infrared
Infrared vibrational spectroscopy (see also near-infrared spectroscopy) is a technique that can be used to identify molecules by analysis of their constituent bonds.
Near-infrared spectroscopy (NIRS) is a spectroscopic method that uses the near-infrared region of the electromagnetic spectrum (from 780 nm to 2500 nm).

Microwave

microwavesmicrowave radiationmicrowave tube
Microwaves occupy a place in the electromagnetic spectrum with frequency above ordinary radio waves, and below infrared light:

Image intensifier

image intensifiersImage Intensifier tubeimage converter
An image intensifier or image intensifier tube is a vacuum tube device for increasing the intensity of available light in an optical system to allow use under low-light conditions, such as at night, to facilitate visual imaging of low-light processes, such as fluorescence of materials in X-rays or gamma rays (X-ray image intensifier), or for conversion of non-visible light sources, such as near-infrared or short wave infrared to visible.

Telescope

telescopestelescopicspyglass
Infrared astronomy uses sensor-equipped telescopes to penetrate dusty regions of space such as molecular clouds, detect objects such as planets, and to view highly red-shifted objects from the early days of the universe.
An optical telescope gathers and focuses light mainly from the visible part of the electromagnetic spectrum (although some work in the infrared and ultraviolet).

Infrared window

atmospheric windowatmospheric transmission windowatmospheric windows
These letters are commonly understood in reference to atmospheric windows and appear, for instance, in the titles of many papers.
The infrared atmospheric window is the overall dynamic property of the earth's atmosphere, taken as a whole at each place and occasion of interest, that lets some infrared radiation from the cloud tops and land-sea surface pass directly to space without intermediate absorption and re-emission, and thus without heating the atmosphere.

Far infrared

far-infraredFIRfar-infrared detector
mid- and far-infrared are progressively further from the visible spectrum.
Far infrared (FIR) is a region in the infrared spectrum of electromagnetic radiation.

Microbolometer

microbolometersuncooled microbolometer
Long-wave infrared: 8 to 12, or 7 to 14 µm (this is the atmospheric window covered by HgCdTe and microbolometers).
Infrared radiation with wavelengths between 7.5–14 μm strikes the detector material, heating it, and thus changing its electrical resistance.

Micrometre

µmμmmicrometers
The micrometre is a common unit of measurement for wavelengths of infrared radiation as well as sizes of biological cells and bacteria, and for grading wool by the diameter of the fibres.

Night-vision device

night vision gogglesnight vision devicenight-vision goggles
Night vision devices operate through a process involving the conversion of ambient light photons into electrons that are then amplified by a chemical and electrical process and then converted back into visible light.
The image may be a conversion to visible light of both visible light and near-infrared, while by convention detection of thermal infrared is denoted thermal imaging.

Thermographic camera

infrared sensorinfrared camerathermal camera
Thermographic cameras detect radiation in the infrared range of the electromagnetic spectrum (roughly 900–14,000 nanometers or 0.9–14 μm) and produce images of that radiation.
A thermographic camera (also called an infrared camera or thermal imaging camera or infrared thermography) is a device that forms a heat zone image using infrared radiation, similar to a common camera that forms an image using visible light.

Infrared photography

infraredinfrared filminfra-red photography
In infrared photography, infrared filters are used to capture the near-infrared spectrum.
Top: tree photographed in the near infrared range.

Emissivity

emissivitiesEmissivity of Earth's atmosphereemitted
The concept of emissivity is important in understanding the infrared emissions of objects.
Thermal radiation is electromagnetic radiation and it may include both visible radiation (light) and infrared radiation, which is not visible to human eyes.

Hertz

MHzkHzHz
IR wavelengths extend from the nominal red edge of the visible spectrum at 700 nanometers (frequency 430 THz), to 1 millimeter (300 GHz).
Light is electromagnetic radiation that is even higher in frequency, and has frequencies in the range of tens (infrared) to thousands (ultraviolet) of terahertz.

Wien's displacement law

radiatesBecause the Earth's surface is colderconstant
Thermal infrared radiation also has a maximum emission wavelength, which is inversely proportional to the absolute temperature of object, in accordance with Wien's displacement law.
A piece of metal heated by a blow torch first becomes "red hot" as the very longest visible wavelengths appear red, then becomes more orange-red as the temperature is increased, and at very high temperatures would be described as "white hot" as shorter and shorter wavelengths come to predominate the black body emission spectrum. Before it had even reached the red hot temperature, the thermal emission was mainly at longer infrared wavelengths, which are not visible; nevertheless, that radiation could be felt as it warms one's nearby skin.