Infrared (IR) light is electromagnetic radiation with longer wavelengths than those of visible light, extending from the nominal red edge of the visible spectrum at 0.74 micrometres (µm) to 300 µm. This range of wavelengths corresponds to a frequency range of approximately 1 to 400 THz, and includes most of the thermal radiation emitted by objects near room temperature. Infrared light is emitted or absorbed by molecules when they change their rotational-vibrational movements. The existence of infrared radiation was first discovered in 1800 by astronomer William Herschel.
Much of the energy from the Sun arrives on Earth in the form of infrared radiation. Sunlight at zenith provides an irradiance of just over 1 kilowatt per square meter at sea level. Of this energy, 527 watts is infrared radiation, 445 watts is visible light, and 32 watts is ultraviolet radiation. The balance between absorbed and emitted infrared radiation has a critical effect on the Earth's climate.
Infrared light is used in industrial, scientific, and medical applications. Night-vision devices using infrared illumination allow people or animals to be observed without the observer being detected. In astronomy, imaging at infrared wavelengths allows observation of objects obscured by interstellar dust. Infrared imaging cameras are used to detect heat loss in insulated systems, to observe changing blood flow in the skin, and to detect overheating of electrical apparatus.
|Name||Wavelength||Frequency (Hz)||Photon Energy (eV)|
|Gamma ray||less than 0.01 nm||more than 10 EHZ||100 keV - 300+ GeV|
|X-Ray||0.01 nm to 10 nm||30 EHz - 30 PHZ||120 eV to 120 keV|
|Ultraviolet||10 nm - 390 nm||30 PHZ - 790 THz||3 eV to 124 eV|
|Visible||390 nm - 750 nm||790 THz - 405 THz||1.7 eV - 3.3 eV|
|Infrared||750 nm - 1 mm||405 THz - 300 GHz||1.24 meV - 1.7 eV|
|Microwave||1 mm - 1 meter||300 GHz - 300 MHz||1.24 µeV - 1.24 meV|
|Radio||1 mm - 100,000 km||300 GHz - 3 Hz||12.4 feV - 1.24 meV|
Infrared imaging is used extensively for military and civilian purposes. Military applications include target acquisition, surveillance, night vision, homing and tracking. Non-military uses include thermal efficiency analysis, environmental monitoring, industrial facility inspections, remote temperature sensing, short-ranged wireless communication, spectroscopy, and weather forecasting. 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.
Humans at normal body temperature radiate chiefly at wavelengths around 10 μm (micrometers), as shown by Wien's displacement law.
At the atomic level, infrared energy elicits vibrational modes in a molecule through a change in the dipole moment, making it a useful frequency range for study of these energy states for molecules of the proper symmetry. Infrared spectroscopy examines absorption and transmission of photons in the infrared energy range, based on their frequency and intensity.
Other articles related to "infrared":
... Two-Micron Sky Survey, or IRc, or Infrared compact, or Caltech infrared catalog is the astronomical catalogue of the infrared sources published in the 1969 by Neugebauer and Leighton ...
... Editing help is available The discovery of infrared radiation is ascribed to William Herschel, the astronomer, in the early 19th century ... Herschel used a prism to refract light from the sun and detected the infrared, beyond the red part of the spectrum, through an increase in the temperature recorded on a thermometer ... The term 'Infrared' did not appear until late in the 19th century ...
... Its principle is based on an infrared localisation system, composed of an infrared camera and at least three infrared transmitters attached to each bony fragment ...
... In this scenario, the target itself provides the (infrared) emissions that the missile's Infrared homing sensor is able to detect lock-on occurs when the missile is ...
... Council of Canada conducted a three-dimensional infrared scan ... Data from the scan and infrared were used by Bruno Mottin of the French Museums' "Center for Research and Restoration" to argue that the transparent gauze veil worn by the sitter is a guarnello, typically used by ... Lisa underwent a major scientific observation that proved through infrared cameras she was originally wearing a bonnet and clutching her chair, something that da Vinci decided to change as ...