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tewa · 08-16-2005

http://www.answers.com/topic/infrared-1

infrared radiation, electromagnetic radiation having a wavelength in the range from c.75 × 10−6 cm to c.100,000 × 10−6 cm (0.000075–0.1 cm). Infrared rays thus occupy that part of the electromagnetic spectrum with a frequency less than that of visible light and greater than that of most radio waves, although there is some overlap. The name infrared means “below the red,” i.e., beyond the red, or lower-frequency (longer wavelength), end of the visible spectrum. Infrared radiation is thermal, or heat, radiation. It was first discovered in 1800 by Sir William Herschel, who was attempting to determine the part of the visible spectrum with the minimum associated heat in connection with astronomical observations he was making. In 1847, A. H. L. Fizeau and J. B. L.

Foucault showed that infrared radiation has the same properties as visible light, being reflected, refracted, and capable of forming an interference pattern. Infrared radiation is typically produced by objects whose temperature is above 10K.

There are many applications of infrared radiation. A number of these are analogous to similar uses of visible light. Thus, the spectrum of a substance in the infrared range can be used in chemical analysis much as the visible spectrum is used. Radiation at discrete wavelengths in the infrared range is characteristic of many molecules. The temperature of a distant object can also be determined by analysis of the infrared radiation from the object. Radiometers operating in the infrared range serve as the basis for many instruments, including heat-seeking devices in missiles and devices for spotting and photographing persons and objects in the dark or in fog. Medical uses of infrared radiation range from the simple heat lamp to the technique of thermal imaging, or thermography. A thermograph of a person can show areas of the body where the temperature is much higher or lower than normal, thus indicating some medical problem. Thermography has also been used in industry and other applications. Some lasers produce infrared radiation. A recent development has been the expansion of research in infrared astronomy; infrared sensors are sent aloft in balloons, rockets, and satellites to study the infrared radiation reaching the earth from other parts of the solar system and beyond.

infrared radiation (in-fruh-red)

Invisible radiation in the part of the electromagnetic spectrum characterized by wavelengths just longer than those of ordinary visible red light and shorter than those of microwaves or radio waves.

The heat we feel from a glowing coal or an incandescent light bulb is from infrared rays.

Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. The name means "below red" (from the Latin infra, "below"), red being the color of visible light of longest wavelength. Infrared radiation spans three orders of magnitude and has wavelengths between 700 nm and 1 mm.

Different regions in the infrared
IR is often subdivided into:

near infrared NIR, IR-A DIN, 0.7–1.4 µm in wavelength, defined by the water absorption, and commonly used in fiber optic telecommunication because of low attenuation losses in the SiO2 glass (silica) medium.
short wavelength IR SWIR, IR-B DIN, 1.4–3 µm, water absorption increases significantly at 1450 nm
mid wavelength IR MWIR, IR-C DIN, also intermediate-IR (IIR), 3–8 µm
long wavelength IR LWIR, IR-C DIN, 8–15 µm)
far infrared FIR, 15–1000 µm
However, these terms are not precise, and are used differently in various studies i.e. near (0.7–5 µm) / mid (5–30 µm) / long (30–1000 µm). Especially at the telecom-wavelengths the spectrum is further subdivided into individual bands, due to limitations of detectors, amplifiers and sources. Infrared radiation is often linked to heat, since objects at room temperature or above will emit radiation mostly concentrated in the mid-infrared band (see black body).

The common nomenclature is justified by the different human response to this radiation (near infrared = the red you just cannot see, far IR = thermal radiation), other definitions follow different physical mechanisms (emission peaks, vs. bands, water absorption) and the newest follow technical reasons (The common silicon detectors are sensitive to about 1050 nm, while InGaAs sensitivity starts around 950 nm and ends between 1700 and 2200 nm, depending on the specific configuration). Unfortunately the international standards for these specifications are not currently available.

Plot of atmospheric transmittance in the infrared region of the electromagnetic spectrum.
Telecommunication bands in the infrared
Optical telecommunication in the near infrared is technically often separated to different frequency bands because of availability of light sources, transmitting /absorbing materials (fibers) and detectors.

O-band 1260–1360 nm
E-band 1360–1460 nm
S-band 1460–1530 nm
C-band 1530–1565 nm
L-band 1565–1625 nm
U-band 1625–1675 nm

The Earth as an infrared emitter
The Earth's surface absorbs visible radiation from the sun and re-emits much of the energy as infrared back to the atmosphere. Certain gases in the atmosphere, chiefly water vapor, absorb this infrared, and re-radiate it in all directions including back to Earth. Thus, the greenhouse effect, keeps the atmosphere and surface much warmer than if the infrared absorbers were absent from the atmosphere.

Night Vision
Infrared is used in night-vision equipment, when there is insufficient visible light to see an object. The radiation is detected and turned into an image on a screen, hotter objects showing up brighter, enabling the police and military to acquire thermally significant targets, such as human beings and automobiles.

Smoke is more transparent to infrared than to visible light, so fire fighters use infrared imaging equipment when working in smoke-filled areas because it does not interfere with other devices in adjoining rooms - this is especially important in areas of high population density (IR does not penetrate walls).

Other Imaging
In infrared photography, infrared filters are used to capture only the infrared spectrum. Digital cameras often use infrared blockers. Cheaper digital cameras and some camera phones which do not have appropriate filters can "see" infrared, appearing as a bright white colour (try pointing a TV remote at your digital camera). This is especially pronounced when taking pictures of subjects near bright areas (such as near a lamp), where the resulting infrared interference can wash out the image.

Thermography
Infrared radiation can be used to remotely determine the temperature of objects (if the emissivity is known). This is termed thermography, or in the case of very hot objects in the NIR or visible it is termed pyrometry. Thermography (thermal imaging) is mainly used in military and industrial applications but the technology is reaching the public market in the form of infrared cameras on cars due to the massively reduced production costs.

Heating
Infrared radiation is used in Infrared saunas to heat the sauna's occupants
(An infrared sauna is an area that heats it's occupants with heaters that emit Far Infrared Ray radiation. Unlike conventional saunas, which use heated steam, an infrared sauna does not heat the air. An infrared sauna is usually a wooden box containing several infrared heaters, although an infrared sauna could be open air and still heat the user's in the same manner. In essence, the sauna box creates the atmosphere of the sauna while the heaters create the actual sauna effect.

Far Infrared Rays are invisible band of light warms objects without warming the air between the source and the object (known as conversion). This radiant heat can also be called Infrared Energy (IR). This band of light is not visible to human eyes but can be seen by special instruments that translate infrared into colors that are visible to our eyes. The best example of Infrared Energy is the sun (80% of the sun’s rays are infrared). Our atmosphere allows IR rays in the 7 to 14 micrometre range to safely reach the Earth’s surface. When warmed, the Earth radiates infrared rays with its peak output at 10 micrometres. The human body radiates infrared energy out through the skin at 3 to 50 micrometres, with most around 9.4 micrometres.) and to remove ice from the wings of aircraft (de-icing).

Communications
IR data transmission is also employed in short-range communication among computer peripherals and personal digital assistants. These devices usually conform to standards published by IrDA, the Infrared Data Association. Remote controls and IrDA devices use infrared light-emitting diodes (LEDs) to emit infrared radiation which is focused by a plastic lens into a narrow beam. The beam is modulated, i.e. switched on and off, to encode the data. The receiver uses a silicon photodiode to convert the infrared radiation to an electric current. It responds only to the rapidly pulsing signal created by the transmitter, and filters out slowly changing infrared radiation from ambient light.

Spectroscopy
Infrared radiation spectroscopy is the study of the composition of (usually) organic compounds, finding out a compound's structure and composition based on the percent transmittance of IR radiation through a sample. Different frequencies are absorbed by different stretches and bends in the molecular bonds occurring inside the sample. Carbon dioxide, for example, has an absorption band at 4.2µm.

History
The discovery of infrared radiation is commonly ascribed to William Herschel, the astronomer in the early 19th century. Herschel used a prism to refract light from a hot source and detected the infrared, beyond the red part of the spectrum, through an increase in the temperature recorded on a thermometer.

references
1.) Encyclopedia information about infrared
The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2003, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/

2.)Science information about infrared
The New Dictionary of Cultural Literacy, Third Edition Edited by E.D. Hirsch, Jr., Joseph F. Kett, and James Trefil. Copyright © 2002 by Houghton Mifflin Company. Published by Houghton Mifflin.

3.) WordNet information about infrared
WordNet 1.7.1 Copyright © 2001 by Princeton University

4.) Military information about infrared
US Department of Defense Dictionary of Military and Associated Words, 2003.

5.) Wikipedia information about infrared
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Infrared

08-16-2005	#20 (permalink)
tewa Sansai Join Date: May 2004 Location: Australia Posts: 226	Lets start with some general information http://www.answers.com/topic/infrared-1 infrared radiation, electromagnetic radiation having a wavelength in the range from c.75 × 10−6 cm to c.100,000 × 10−6 cm (0.000075–0.1 cm). Infrared rays thus occupy that part of the electromagnetic spectrum with a frequency less than that of visible light and greater than that of most radio waves, although there is some overlap. The name infrared means “below the red,” i.e., beyond the red, or lower-frequency (longer wavelength), end of the visible spectrum. Infrared radiation is thermal, or heat, radiation. It was first discovered in 1800 by Sir William Herschel, who was attempting to determine the part of the visible spectrum with the minimum associated heat in connection with astronomical observations he was making. In 1847, A. H. L. Fizeau and J. B. L. Foucault showed that infrared radiation has the same properties as visible light, being reflected, refracted, and capable of forming an interference pattern. Infrared radiation is typically produced by objects whose temperature is above 10K. There are many applications of infrared radiation. A number of these are analogous to similar uses of visible light. Thus, the spectrum of a substance in the infrared range can be used in chemical analysis much as the visible spectrum is used. Radiation at discrete wavelengths in the infrared range is characteristic of many molecules. The temperature of a distant object can also be determined by analysis of the infrared radiation from the object. Radiometers operating in the infrared range serve as the basis for many instruments, including heat-seeking devices in missiles and devices for spotting and photographing persons and objects in the dark or in fog. Medical uses of infrared radiation range from the simple heat lamp to the technique of thermal imaging, or thermography. A thermograph of a person can show areas of the body where the temperature is much higher or lower than normal, thus indicating some medical problem. Thermography has also been used in industry and other applications. Some lasers produce infrared radiation. A recent development has been the expansion of research in infrared astronomy; infrared sensors are sent aloft in balloons, rockets, and satellites to study the infrared radiation reaching the earth from other parts of the solar system and beyond. infrared radiation (in-fruh-red) Invisible radiation in the part of the electromagnetic spectrum characterized by wavelengths just longer than those of ordinary visible red light and shorter than those of microwaves or radio waves. The heat we feel from a glowing coal or an incandescent light bulb is from infrared rays. Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. The name means "below red" (from the Latin infra, "below"), red being the color of visible light of longest wavelength. Infrared radiation spans three orders of magnitude and has wavelengths between 700 nm and 1 mm. Different regions in the infrared IR is often subdivided into: near infrared NIR, IR-A DIN, 0.7–1.4 µm in wavelength, defined by the water absorption, and commonly used in fiber optic telecommunication because of low attenuation losses in the SiO2 glass (silica) medium. short wavelength IR SWIR, IR-B DIN, 1.4–3 µm, water absorption increases significantly at 1450 nm mid wavelength IR MWIR, IR-C DIN, also intermediate-IR (IIR), 3–8 µm long wavelength IR LWIR, IR-C DIN, 8–15 µm) far infrared FIR, 15–1000 µm However, these terms are not precise, and are used differently in various studies i.e. near (0.7–5 µm) / mid (5–30 µm) / long (30–1000 µm). Especially at the telecom-wavelengths the spectrum is further subdivided into individual bands, due to limitations of detectors, amplifiers and sources. Infrared radiation is often linked to heat, since objects at room temperature or above will emit radiation mostly concentrated in the mid-infrared band (see black body). The common nomenclature is justified by the different human response to this radiation (near infrared = the red you just cannot see, far IR = thermal radiation), other definitions follow different physical mechanisms (emission peaks, vs. bands, water absorption) and the newest follow technical reasons (The common silicon detectors are sensitive to about 1050 nm, while InGaAs sensitivity starts around 950 nm and ends between 1700 and 2200 nm, depending on the specific configuration). Unfortunately the international standards for these specifications are not currently available. Plot of atmospheric transmittance in the infrared region of the electromagnetic spectrum. Telecommunication bands in the infrared Optical telecommunication in the near infrared is technically often separated to different frequency bands because of availability of light sources, transmitting /absorbing materials (fibers) and detectors. O-band 1260–1360 nm E-band 1360–1460 nm S-band 1460–1530 nm C-band 1530–1565 nm L-band 1565–1625 nm U-band 1625–1675 nm The Earth as an infrared emitter The Earth's surface absorbs visible radiation from the sun and re-emits much of the energy as infrared back to the atmosphere. Certain gases in the atmosphere, chiefly water vapor, absorb this infrared, and re-radiate it in all directions including back to Earth. Thus, the greenhouse effect, keeps the atmosphere and surface much warmer than if the infrared absorbers were absent from the atmosphere. Night Vision Infrared is used in night-vision equipment, when there is insufficient visible light to see an object. The radiation is detected and turned into an image on a screen, hotter objects showing up brighter, enabling the police and military to acquire thermally significant targets, such as human beings and automobiles. Smoke is more transparent to infrared than to visible light, so fire fighters use infrared imaging equipment when working in smoke-filled areas because it does not interfere with other devices in adjoining rooms - this is especially important in areas of high population density (IR does not penetrate walls). Other Imaging In infrared photography, infrared filters are used to capture only the infrared spectrum. Digital cameras often use infrared blockers. Cheaper digital cameras and some camera phones which do not have appropriate filters can "see" infrared, appearing as a bright white colour (try pointing a TV remote at your digital camera). This is especially pronounced when taking pictures of subjects near bright areas (such as near a lamp), where the resulting infrared interference can wash out the image. Thermography Infrared radiation can be used to remotely determine the temperature of objects (if the emissivity is known). This is termed thermography, or in the case of very hot objects in the NIR or visible it is termed pyrometry. Thermography (thermal imaging) is mainly used in military and industrial applications but the technology is reaching the public market in the form of infrared cameras on cars due to the massively reduced production costs. Heating Infrared radiation is used in Infrared saunas to heat the sauna's occupants (An infrared sauna is an area that heats it's occupants with heaters that emit Far Infrared Ray radiation. Unlike conventional saunas, which use heated steam, an infrared sauna does not heat the air. An infrared sauna is usually a wooden box containing several infrared heaters, although an infrared sauna could be open air and still heat the user's in the same manner. In essence, the sauna box creates the atmosphere of the sauna while the heaters create the actual sauna effect. Far Infrared Rays are invisible band of light warms objects without warming the air between the source and the object (known as conversion). This radiant heat can also be called Infrared Energy (IR). This band of light is not visible to human eyes but can be seen by special instruments that translate infrared into colors that are visible to our eyes. The best example of Infrared Energy is the sun (80% of the sun’s rays are infrared). Our atmosphere allows IR rays in the 7 to 14 micrometre range to safely reach the Earth’s surface. When warmed, the Earth radiates infrared rays with its peak output at 10 micrometres. The human body radiates infrared energy out through the skin at 3 to 50 micrometres, with most around 9.4 micrometres.) and to remove ice from the wings of aircraft (de-icing). Communications IR data transmission is also employed in short-range communication among computer peripherals and personal digital assistants. These devices usually conform to standards published by IrDA, the Infrared Data Association. Remote controls and IrDA devices use infrared light-emitting diodes (LEDs) to emit infrared radiation which is focused by a plastic lens into a narrow beam. The beam is modulated, i.e. switched on and off, to encode the data. The receiver uses a silicon photodiode to convert the infrared radiation to an electric current. It responds only to the rapidly pulsing signal created by the transmitter, and filters out slowly changing infrared radiation from ambient light. Spectroscopy Infrared radiation spectroscopy is the study of the composition of (usually) organic compounds, finding out a compound's structure and composition based on the percent transmittance of IR radiation through a sample. Different frequencies are absorbed by different stretches and bends in the molecular bonds occurring inside the sample. Carbon dioxide, for example, has an absorption band at 4.2µm. History The discovery of infrared radiation is commonly ascribed to William Herschel, the astronomer in the early 19th century. Herschel used a prism to refract light from a hot source and detected the infrared, beyond the red part of the spectrum, through an increase in the temperature recorded on a thermometer. references 1.) Encyclopedia information about infrared The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2003, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/ 2.)Science information about infrared The New Dictionary of Cultural Literacy, Third Edition Edited by E.D. Hirsch, Jr., Joseph F. Kett, and James Trefil. Copyright © 2002 by Houghton Mifflin Company. Published by Houghton Mifflin. 3.) WordNet information about infrared WordNet 1.7.1 Copyright © 2001 by Princeton University 4.) Military information about infrared US Department of Defense Dictionary of Military and Associated Words, 2003. 5.) Wikipedia information about infrared This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Infrared __________________ There is no such thing as a zero maintenance pond but the closer you get the more time to enjoy your koi. Soft low TDS water is the perfect pond water. http://www.tewakoi.com