
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 1 E-7 m Nanometre and 1 millimetre. ===Different regions in the infrared=== IR is often subdivided into: * near infrared NIR, IR-A ''DIN'', 0.7–1.4 micrometre 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 spontaneous emission 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. ===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. == Applications == ===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 filter are used to capture only the infrared spectrum. Digital cameras often use infrared blocker. 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 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 (optics) into a narrow beam. The beam is modulation, 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 (electricity). 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. ==See Also== *Night vision *infrared photography *Thermography Electromagnetic spectrum Infrared
"If your computer monitor is warm, the following patch should be coloured infrared" I like this joke a lot :-D. But technically, ''all'' objects above :absolute zero radiate infrared, right? I imagine if something gets cold enough its :black body spectrum will have very little infrared in it, with the peak dropping down into the frequencies below infrared. There will still be infrared emission, but I'm not sure if the swatch could be termed to be ''colored'' infrared at that point. Maybe it would be colored :microwave. considering that no one can "see" infrared, it seems wierd to say that it is colored as such. if the combination of colors creates other colors, then the square can't be "colored" infrared because it would then be a combination. if you say that it just emits or reflects infrared, then the color is still meaningless, because any visible color could do that if it contains IR reflective qualities. and, black would both emit and absorb IR since it absorbs, and it gets hot. ----- Who wrote that about sunburn? are you sure? "Although relatively harmless, overexposure to IR can cause damage to cells and is the cause of :sunburn (despite :ultraviolet commonly being thought of as the culprit.)" Scientific American seems to diagree: http://www.sciam.com/askexpert/medicine/medicine57/ --rmhermen -------- How does the infrared in remote controls work? How does our sensation of radiated heat work? Does our skin sense infra-red, or does it heat up because of it and we then sense the heat (are the two different?) -- User:Tarquin 16:47 7 Jun 2003 (UTC) I put in a few sentences about remote controls. As for skin, it senses heat, not radiation directly. There is a difference. Direct radiation sensing, as happens in the eye, is a photochemical process caused by photons colliding with light-sensitive (and, if you're a cat, IR-sensitive) molecules. These molecules are highly selective about what wavelength of photon they respond to, which is why we can see in colour. Heat receptors in the skin are different. It seems that nobody knows how they work, but they just sense temperature in the bulk of the skin. This temperature is mediated by mechanical vibrations of atoms, not by radiation. The skin receptors don't know if the heat got there by IR radiation, or by conduction from a hot object. By the way, some snakes can see infra-red, too, but they do it in a different way from mammals with IR-sensitive eyes. Their IR sensors, called ''pits'', are separate from their eyes. The pits detect IR by its heating effect on the skin inside the pit. They can work out which part of the pit is hottest, and therefore roughly where the hot object is. -- User:Heron : thanks! The above is probably enough to make a start on Thermoception. -- User:Tarquin 19:45 7 Jun 2003 (UTC) == Infrared as a color == Do you have any way to modify the human eye so that we can see infrared as a color?? This should be known by 2100. :It should? omigosh I better get to work then! WTF?!--User:Deglr6328 16:31, 16 Aug 2004 (UTC) ::http://www.amasci.com/amateur/irgoggl.html Yes, and for $10.00. --Alexander == Fahrenheit and Celsius scales == The image only has a Fahrenheit scale. Does anybody know how to add a Celsius scale to it? User:Bobblewik User talk:Bobblewik 12:16, 10 Oct 2004 (UTC) :Done. --User:Heron 09:37, 12 Nov 2004 (UTC) == what danger can infrared cause? == It's non-ionising, so the only danger is due to heating. In other words, if it's powerful enough, it will burn your skin. --User:Heron 09:08, 12 Nov 2004 (UTC) This is only tue in a certain range of pulse lengths and intensities. There are several effects involved at higher intensities (like these found in lasers), like multiphoton processes, plasma generation and such. But in the low intensity case the heating effect is the dominant. --User:BoP 11:44, 2 Jan 2005 (UTC) == 15 micron band saturation and the greenhouse gas effect == I am doing some research on the question of the carbon dioxide greenhouse effect. Specifically, some critics of Global Warming claim that the 15 micron band is "optically saturated" for CO2 in the atmosphere. Further increases in CO2 will not have the expected effect, they argue, since the band cannot absorb anymore. There just ain't more 15 micron IR left to absorb. We would appreciate any info you could provide on this question. Specifically, how does the IPCC model IR saturation in the 15 micron band for the climate change predictions? == IR vs Heat == The article and discussion here seems to reflect a common misconception about IR that I'd like to clear up. Basically, IR does not equal heat, "heat radiation", etc. Warm/hot objects radiate many wavelengths of electromagnetic radiation ("light"), INCLUDING infrared. Have you ever seen something extremely hot glow red? Or get hotter and glow orange, then yellow, then white? Same phenomenon.It glows IR first, you just can't see it. As for transmission of heat via IR, well yeah. Absorption of any wavelength of "light" warms things, INCLUDING infrared. Um, that's all. Thanks. *EDIT* After adding this comment, I went to clarify the article, and realized that this misconception /wasn't/ reflected in it after all. But in that case, what prompted me to post this and "fix" it? Twilight zone...
See other meanings of words starting from letter:
Words begining with Infrared:
Infrared
Infrared
Infrared-guided
Infrared-homing
Infrared_Astronomical_Satellite
Infrared_Astronomy
Infrared_astronomy
Infrared_camera
Infrared_camera
Infrared_cutoff
Infrared_Data_Association
Infrared_Data_Association
Infrared_divergence
Infrared_filter
Infrared_fixed_point
Infrared_guidance
Infrared_homing
Infrared_hurricane_bob.mpg
Infrared_light
Infrared_Optical_Telescope_Array
Infrared_photography
Infrared_Radiation
Infrared_radiation
Infrared_sauna
Infrared_Search_and_Track
Infrared_search_and_tracking
Infrared_search_and_track_(IRST)
Infrared_seeker
Infrared_seeking
Infrared_Space_Observatory
Infrared_spectrometry
Infrared_spectroscopy
Infrared_spectroscopy
Infrared
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 1 E-7 m Nanometre and 1 millimetre. ===Different regions in the infrared=== IR is often subdivided into: * near infrared NIR, IR-A ''DIN'', 0.7–1.4 micrometre 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 spontaneous emission 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. ===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. == Applications == ===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 filter are used to capture only the infrared spectrum. Digital cameras often use infrared blocker. 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 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 (optics) into a narrow beam. The beam is modulation, 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 (electricity). 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. ==See Also== *Night vision *infrared photography *Thermography Electromagnetic spectrum Infrared
Infrared
"If your computer monitor is warm, the following patch should be coloured infrared" I like this joke a lot :-D. But technically, ''all'' objects above :absolute zero radiate infrared, right? I imagine if something gets cold enough its :black body spectrum will have very little infrared in it, with the peak dropping down into the frequencies below infrared. There will still be infrared emission, but I'm not sure if the swatch could be termed to be ''colored'' infrared at that point. Maybe it would be colored :microwave. considering that no one can "see" infrared, it seems wierd to say that it is colored as such. if the combination of colors creates other colors, then the square can't be "colored" infrared because it would then be a combination. if you say that it just emits or reflects infrared, then the color is still meaningless, because any visible color could do that if it contains IR reflective qualities. and, black would both emit and absorb IR since it absorbs, and it gets hot. ----- Who wrote that about sunburn? are you sure? "Although relatively harmless, overexposure to IR can cause damage to cells and is the cause of :sunburn (despite :ultraviolet commonly being thought of as the culprit.)" Scientific American seems to diagree: http://www.sciam.com/askexpert/medicine/medicine57/ --rmhermen -------- How does the infrared in remote controls work? How does our sensation of radiated heat work? Does our skin sense infra-red, or does it heat up because of it and we then sense the heat (are the two different?) -- User:Tarquin 16:47 7 Jun 2003 (UTC) I put in a few sentences about remote controls. As for skin, it senses heat, not radiation directly. There is a difference. Direct radiation sensing, as happens in the eye, is a photochemical process caused by photons colliding with light-sensitive (and, if you're a cat, IR-sensitive) molecules. These molecules are highly selective about what wavelength of photon they respond to, which is why we can see in colour. Heat receptors in the skin are different. It seems that nobody knows how they work, but they just sense temperature in the bulk of the skin. This temperature is mediated by mechanical vibrations of atoms, not by radiation. The skin receptors don't know if the heat got there by IR radiation, or by conduction from a hot object. By the way, some snakes can see infra-red, too, but they do it in a different way from mammals with IR-sensitive eyes. Their IR sensors, called ''pits'', are separate from their eyes. The pits detect IR by its heating effect on the skin inside the pit. They can work out which part of the pit is hottest, and therefore roughly where the hot object is. -- User:Heron : thanks! The above is probably enough to make a start on Thermoception. -- User:Tarquin 19:45 7 Jun 2003 (UTC) == Infrared as a color == Do you have any way to modify the human eye so that we can see infrared as a color?? This should be known by 2100. :It should? omigosh I better get to work then! WTF?!--User:Deglr6328 16:31, 16 Aug 2004 (UTC) ::http://www.amasci.com/amateur/irgoggl.html Yes, and for $10.00. --Alexander == Fahrenheit and Celsius scales == The image only has a Fahrenheit scale. Does anybody know how to add a Celsius scale to it? User:Bobblewik User talk:Bobblewik 12:16, 10 Oct 2004 (UTC) :Done. --User:Heron 09:37, 12 Nov 2004 (UTC) == what danger can infrared cause? == It's non-ionising, so the only danger is due to heating. In other words, if it's powerful enough, it will burn your skin. --User:Heron 09:08, 12 Nov 2004 (UTC) This is only tue in a certain range of pulse lengths and intensities. There are several effects involved at higher intensities (like these found in lasers), like multiphoton processes, plasma generation and such. But in the low intensity case the heating effect is the dominant. --User:BoP 11:44, 2 Jan 2005 (UTC) == 15 micron band saturation and the greenhouse gas effect == I am doing some research on the question of the carbon dioxide greenhouse effect. Specifically, some critics of Global Warming claim that the 15 micron band is "optically saturated" for CO2 in the atmosphere. Further increases in CO2 will not have the expected effect, they argue, since the band cannot absorb anymore. There just ain't more 15 micron IR left to absorb. We would appreciate any info you could provide on this question. Specifically, how does the IPCC model IR saturation in the 15 micron band for the climate change predictions? == IR vs Heat == The article and discussion here seems to reflect a common misconception about IR that I'd like to clear up. Basically, IR does not equal heat, "heat radiation", etc. Warm/hot objects radiate many wavelengths of electromagnetic radiation ("light"), INCLUDING infrared. Have you ever seen something extremely hot glow red? Or get hotter and glow orange, then yellow, then white? Same phenomenon.It glows IR first, you just can't see it. As for transmission of heat via IR, well yeah. Absorption of any wavelength of "light" warms things, INCLUDING infrared. Um, that's all. Thanks. *EDIT* After adding this comment, I went to clarify the article, and realized that this misconception /wasn't/ reflected in it after all. But in that case, what prompted me to post this and "fix" it? Twilight zone...
See other meanings of words starting from letter:
I
IA | IB | IC | ID | IE | IF | IG | IH | IJ | IK | IL | IM | IN | IO | IP | IR | IS | IT | IU | IW | IX | IY | IZ |Words begining with Infrared:
Infrared
Infrared
Infrared-guided
Infrared-homing
Infrared_Astronomical_Satellite
Infrared_Astronomy
Infrared_astronomy
Infrared_camera
Infrared_camera
Infrared_cutoff
Infrared_Data_Association
Infrared_Data_Association
Infrared_divergence
Infrared_filter
Infrared_fixed_point
Infrared_guidance
Infrared_homing
Infrared_hurricane_bob.mpg
Infrared_light
Infrared_Optical_Telescope_Array
Infrared_photography
Infrared_Radiation
Infrared_radiation
Infrared_sauna
Infrared_Search_and_Track
Infrared_search_and_tracking
Infrared_search_and_track_(IRST)
Infrared_seeker
Infrared_seeking
Infrared_Space_Observatory
Infrared_spectrometry
Infrared_spectroscopy
Infrared_spectroscopy
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