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Infrared

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  • ghino_luteria
    Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. The name means
    Message 1 of 22 , Feb 1, 2007
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      Infrared (IR) radiation is electromagnetic radiation of a wavelength
      longer than that of visible light, but shorter than that of radio
      waves. 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 approximately 750 nm and 1 mm.[1]

      The infrared portion of the spectrum has a number of technological
      uses, including target acquisition and tracking by the military;
      remote temperature sensing; short-ranged wireless communication;
      spectroscopy, and weather forecasting. Telescopes equipped with
      infrared sensors are used in infrared astronomy to penetrate dusty
      regions of space, such as molecular clouds; detect low temperature
      objects such as planets orbiting distant stars, and to view highly
      red-shifted objects from the early history of the universe.[2]

      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. Infrared
      spectroscopy is the examination of absorption and transmission of
      photons in the infrared energy range, based on their frequency and
      intensity.[3]
    • ibanezjosec
      Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. The name means
      Message 2 of 22 , Feb 13, 2007
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        Infrared (IR) radiation is electromagnetic radiation of a wavelength
        longer than that of visible light, but shorter than that of radio
        waves. 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 approximately 750 nm and 1 mm.[1]

        The infrared portion of the spectrum has a number of technological
        uses, including target acquisition and tracking by the military;
        remote temperature sensing; short-ranged wireless communication;
        spectroscopy, and weather forecasting. Telescopes equipped with
        infrared sensors are used in infrared astronomy to penetrate dusty
        regions of space, such as molecular clouds; detect low temperature
        objects such as planets orbiting distant stars, and to view highly
        red-shifted objects from the early history of the universe.[2]

        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. Infrared
        spectroscopy is the examination of absorption and transmission of
        photons in the infrared energy range, based on their frequency and
        intensity.[3]
      • matutina_michaeljohn
        Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. The name means
        Message 3 of 22 , Feb 22, 2007
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          Infrared (IR) radiation is electromagnetic radiation of a wavelength
          longer than that of visible light, but shorter than that of radio
          waves. 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
          approximately 750 nm and 1 mm.[1]
        • suzanne_villar
          Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves.
          Message 4 of 22 , Feb 23, 2007
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            Infrared (IR) radiation is electromagnetic radiation of a wavelength
            longer than that of visible light, but shorter than that of radio waves.
          • delapena_brent
            Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. The name means
            Message 5 of 22 , Feb 27, 2007
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              Infrared (IR) radiation is electromagnetic radiation of a wavelength
              longer than that of visible light, but shorter than that of radio
              waves. 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 approximately 750 nm and 1 mm.[1]

              The infrared portion of the spectrum has a number of technological
              uses, including target acquisition and tracking by the military;
              remote temperature sensing; short-ranged wireless communication;
              spectroscopy, and weather forecasting. Telescopes equipped with
              infrared sensors are used in infrared astronomy to penetrate dusty
              regions of space, such as molecular clouds; detect low temperature
              objects such as planets orbiting distant stars, and to view highly
              red-shifted objects from the early history of the universe.[2]

              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. Infrared
              spectroscopy is the examination of absorption and transmission of
              photons in the infrared energy range, based on their frequency and
              intensity.[3]
            • marte_lopez_06
              Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. The name means
              Message 6 of 22 , Feb 28, 2007
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                Infrared (IR) radiation is electromagnetic radiation of a wavelength
                longer than that of visible light, but shorter than that of radio
                waves. 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 approximately 750 nm and 1 mm.[1]

                The infrared portion of the spectrum has a number of technological
                uses, including target acquisition and tracking by the military;
                remote temperature sensing; short-ranged wireless communication;
                spectroscopy, and weather forecasting. Telescopes equipped with
                infrared sensors are used in infrared astronomy to penetrate dusty
                regions of space, such as molecular clouds; detect low temperature
                objects such as planets orbiting distant stars, and to view highly
                red-shifted objects from the early history of the universe.[2]

                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. Infrared
                spectroscopy is the examination of absorption and transmission of
                photons in the infrared energy range, based on their frequency and
                intensity.[3]
              • krezelle_flores
                Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. The name means
                Message 7 of 22 , Feb 28, 2007
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                  Infrared (IR) radiation is electromagnetic radiation of a wavelength
                  longer than that of visible light, but shorter than that of radio
                  waves. 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 approximately 750 nm and 1 mm.[1]

                  The infrared portion of the spectrum has a number of technological
                  uses, including target acquisition and tracking by the military;
                  remote temperature sensing; short-ranged wireless communication;
                  spectroscopy, and weather forecasting. Telescopes equipped with
                  infrared sensors are used in infrared astronomy to penetrate dusty
                  regions of space, such as molecular clouds; detect low temperature
                  objects such as planets orbiting distant stars, and to view highly
                  red-shifted objects from the early history of the universe.[2]

                  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. Infrared
                  spectroscopy is the examination of absorption and transmission of
                  photons in the infrared energy range, based on their frequency and
                  intensity.[3]
                • santoscarmelajane
                  Infrared From Wikipedia, the free encyclopedia Jump to: navigation, search For other uses, see Infrared (disambiguation). Image of two girls in mid-infrared
                  Message 8 of 22 , Jul 14, 2007
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                    Infrared
                    From Wikipedia, the free encyclopedia
                    Jump to: navigation, search
                    For other uses, see Infrared (disambiguation).

                    Image of two girls in mid-infrared ("thermal") light (false-color)
                    Infrared (IR) radiation is electromagnetic radiation of a wavelength
                    longer than that of visible light, but shorter than that of radio
                    waves. The name means "below red" (from the Latin infra, "below"),
                    red being the color of visible light with the longest wavelength.
                    Infrared radiation has wavelengths between about 750 nm and 1 mm,
                    spanning three orders of magnitude.[1]

                    The uses of infrared include military, such as: target acquisition,
                    surveillance, homing and tracking and non-military, such as thermal
                    efficiency analysis, 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 cool
                    objects such as planets, and to view highly red-shifted objects from
                    the early days of the universe.[2]

                    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. Infrared
                    spectroscopy examines absorption and transmission of photons in the
                    infrared energy range, based on their frequency and intensity
                  • sheilamarieflores_03
                    Infrared From Wikipedia, the free encyclopedia (Redirected from Infrared radiation) Jump to: navigation, search For other uses, see Infrared (disambiguation).
                    Message 9 of 22 , Aug 10, 2007
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                      Infrared
                      From Wikipedia, the free encyclopedia
                      (Redirected from Infrared radiation)
                      Jump to: navigation, search
                      For other uses, see Infrared (disambiguation).

                      Image of two girls in mid-infrared ("thermal") light (false-color)
                      Infrared (IR) radiation is electromagnetic radiation of a wavelength
                      longer than that of visible light, but shorter than that of radio
                      waves. The name means "below red" (from the Latin infra, "below"),
                      red being the color of visible light with the longest wavelength.
                      Infrared radiation has wavelengths between about 750 nm and 1 mm,
                      spanning three orders of magnitude.[1]

                      The uses of infrared include military, such as: target acquisition,
                      surveillance, homing and tracking and non-military, such as thermal
                      efficiency analysis, 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 cool
                      objects such as planets, and to view highly red-shifted objects from
                      the early days of the universe.[2]

                      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. Infrared
                      spectroscopy examines absorption and transmission of photons in the
                      infrared energy range, based on their frequency and intensity.[3]

                      Contents [hide]
                      1 Different regions in the infrared
                      1.1 Telecommunication bands in the infrared
                      1.2 Heat
                      2 Applications
                      2.1 Night vision
                      2.2 Thermography
                      2.3 Other imaging
                      2.4 Heating
                      2.5 Communications
                      2.6 Spectroscopy
                      2.7 Meteorology
                      2.8 Climatology
                      2.9 Astronomy
                      2.10 Art history and Archaeology
                      2.11 Biological systems
                      3 The Earth as an infrared emitter
                      4 History of infrared science
                      5 See also
                      6 References
                      7 External links
                      7.1 Journals
                      7.2 Web sites



                      [edit] Different regions in the infrared
                      This article does not cite any references or sources.
                      Please help improve this article by adding citations to reliable
                      sources. (help, get involved!)
                      Unverifiable material may be challenged and removed.
                      This article has been tagged since July 2006.
                      Objects generally emit infrared radiation across a spectrum of
                      wavelengths, but only a specific region of the spectrum is of
                      interest because sensors are usually designed only to collect
                      radiation within a specific bandwidth. As a result, the infrared
                      band is often subdivided into smaller sections. There are no
                      standard divisions, but a commonly used scheme is:[citation needed]

                      Near-infrared (NIR, IR-A DIN): 0.75-1.4 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. Image intensifiers are sensitive to this area
                      of the spectrum, about 1 micron, 1,000 nanometers or 10,000
                      Angstroms. Examples include night vision devices such as night
                      vision goggles.
                      Short-wavelength infrared (SWIR, IR-B DIN): 1.4-3 µm, water
                      absorption increases significantly at 1,450 nm. The 1,530 to 1,560
                      nm range is the dominant spectral region for long-distance
                      telecommunications
                      Mid-wavelength infrared (MWIR, IR-C DIN) also called intermediate
                      infrared (IIR): 3-8 µm. In guided missile technology this is
                      the 'heat seeking' region in which the homing heads of passive IR
                      homing missiles are designed to work, homing on to the IR signature
                      of the target aircraft, typically the jet engine exhaust plume.
                      Long-wavelength infrared (LWIR, IR-C DIN): 8–15 µm. About 10 microns
                      is the "thermal imaging" region, in which sensors can obtain a
                      completely passive picture of the outside world based on thermal
                      emissions only and requiring no external light or thermal source
                      such as the sun, moon or infrared illuminator. Forward-looking
                      infrared (FLIR) systems use this area of the spectrum. Sometimes
                      also called the "far infrared."
                      Far infrared (FIR): 15-1,000 µm (see also far infrared laser)
                      NIR and SWIR is sometimes called reflected infrared while MWIR and
                      LWIR is sometimes referred to as thermal infrared. Due to the nature
                      of the blackbody radiation curves, typical 'hot' objects, such as
                      exhaust pipes, often appear brighter in the MW compared to the same
                      object viewed in the LW.

                      Astronomers typically divide the infrared spectrum as follows:[4]

                      near: (0.7-1) to 5 µm
                      mid: 5 to (25-40) µm
                      long: (25-40) to (200-350) µm
                      These divisions are not precise and can vary depending on the
                      publication. The three regions are used for observation of different
                      temperature ranges, and hence different environments in space.

                      A third scheme divides up the band based on the response of various
                      detectors:[5]

                      Near infrared (NIR): from 0.7 to 1.0 micrometers (from the
                      approximate end of the response of the human eye to that of silicon)
                      Short-wave infrared (SWIR): 1.0 to 3 micrometers (from the cut off
                      of silicon to that of the MWIR atmospheric window. InGaAs covers to
                      about 1.8 micrometers; the less sensitive lead salts cover this
                      region
                      Mid-wave infrared (MWIR): 3 to 5 micrometers (defined by the
                      atmospheric window and covered by InSb and HgCdTe and partially
                      PbSe)
                      Long-wave infrared (LWIR): 8 to 12, or 7 to 14 micrometers: the
                      atmospheric window (Covered by HgCdTe and microbolometers)
                      Very-long wave infrared (VLWIR): 12 to about 30 micrometers, covered
                      by doped silicon
                      These divisions are justified by the different human response to
                      this radiation: near infrared is the region closest in wavelength to
                      the radiation detectable by the human eye, mid and far infrared are
                      progressively further from the visible regime. 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 1,050 nm, while
                      InGaAs' sensitivity starts around 950 nm and ends between 1,700 and
                      2,600 nm, depending on the specific configuration). Unfortunately,
                      international standards for these specifications are not currently
                      available.


                      Plot of atmospheric transmittance in part of the infrared region.The
                      boundary between visible and infrared light is not precisely
                      defined. The human eye is markedly less sensitive to light above 700
                      nm wavelength, so shorter frequencies make insignificant
                      contributions to scenes illuminated by common light sources. But
                      particularly intense light (e.g., from lasers, or from bright
                      daylight with the visible light removed by colored gels[1]) can be
                      detected up to approximately 780 nm, and will be perceived as red
                      light. The onset of infrared is defined (according to different
                      standards) at various values typically between 700 nm and 800 nm.


                      [edit] Telecommunication bands in the infrared
                      In optical communications, the part of the infrared spectrum that is
                      used is divided into several bands based on availability of light
                      sources, transmitting/absorbing materials (fibers) and detectors:[6]

                      Band Descriptor Wavelength range
                      O band Original 1260–1360 nm
                      E band Extended 1360–1460 nm
                      S band Short wavelength 1460–1530 nm
                      C band Conventional 1530–1565 nm
                      L band Long wavelength 1565–1625 nm
                      U band Ultralong wavelength 1625–1675 nm

                      The C-band is the dominant band for long-distance telecommunication
                      networks. The S and L bands are based on less well established
                      technology, and are not as widely deployed.


                      [edit] Heat
                      Main article: Thermal radiation
                      Infrared radiation is popularly known as "heat" or sometimes "heat
                      radiation," since many people attribute all radiant heating to
                      infrared light. This is a widespread misconception, since light and
                      electromagnetic waves of any frequency will heat surfaces that
                      absorb them. Infrared light from the Sun only accounts for 50%
                      [citation needed] of the heating of the Earth, the rest being caused
                      by visible light that is absorbed then re-radiated at longer
                      wavelengths. Visible light or ultraviolet-emitting lasers can char
                      paper and incandescently hot objects emit visible radiation. It is
                      true that objects at room temperature will emit radiation mostly
                      concentrated in the 8-12 micron band, but this is not distinct from
                      the emission of visible light by incandescent objects and
                      ultraviolet by even hotter objects (see black body and Wien's
                      displacement law).[7]

                      Heat is energy in transient form that flows due to temperature
                      difference. Unlike heat transmitted by thermal conduction or thermal
                      convection, radiation can propagate through a vacuum.

                      The concept of emissivity is important in understanding the infrared
                      emissions of objects. This is a property of a surface which
                      describes how its thermal emissions deviate from the ideal of a
                      blackbody. To further explain, two objects at the same physical
                      temperature will not 'appear' the same temperature in an infrared
                      image if they have differing emissivities.


                      [edit] Applications
                      This article does not cite any references or sources.
                      Please help improve this article by adding citations to reliable
                      sources. (help, get involved!)
                      Unverifiable material may be challenged and removed.
                      This article has been tagged since July 2006.

                      [edit] 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 in different shades than cooler objects, enabling the
                      police and military to distinguish warm targets, such as human
                      beings and automobiles. Also see Forward looking infrared. IR
                      radiation is a secondary effect of heat; it is not heat itself. Heat
                      itself is a measure of the translational energy of an amount of
                      matter. "Thermal" detectors do not actually detect heat directly but
                      the difference in IR radiation from objects. The device itself that
                      detects the radiation is known as a photocathode. Military gunnery
                      ranges sometimes use special materials that reflect IR radiation to
                      simulate enemy vehicles with running engines. The targets can be at
                      the exact same temperature as the surrounding terrain, but they emit
                      (reflect) much more IR radiation. Different materials emit more or
                      less IR radiation as temperature increases or decreases, depending
                      on the composition of the material. Infrared imagery is usually
                      formed as a result of the integrated inband intensity of the
                      radiation, based on temperate and emissivity.

                      Simple infrared sensors were used by British, American and German
                      forces in the Second World War as night vision aids for snipers.

                      Smoke is more transparent to infrared than to visible light, so
                      firefighters use infrared imaging equipment when working in smoke-
                      filled areas.


                      [edit] Thermography

                      A thermographic image of a dogInfrared thermography is a non-
                      contact, non-destructive test method that utilizes a thermal imager
                      to detect, display and record thermal patterns and temperatures
                      across the surface of an object. Infrared thermography may be
                      applied to any situation where knowledge of thermal profiles and
                      temperatures will provide meaningful data about a system, object or
                      process. Thermography is widely used in industry for predictive
                      maintenance, condition assessment, quality assurance, and forensic
                      investigations of electrical, mechanical and structural systems.
                      Other applications include, but are not limited to: law enforcement,
                      firefighting, search and rescue, and medical and veterinary sciences.

                      Aside from test equipment, training is the most important investment
                      a company will make in an infrared inspection program. Advances in
                      technology have provided infrared equipment that is user-friendly;
                      however, infrared thermography is not a "simply point and shoot"
                      technology. In addition to understanding the object or system being
                      inspected, thermographers must also understand common error sources
                      that can influence observed thermal data. Typically,infrared
                      training courses should cover the topics of infrared theory, heat
                      transfer concepts, equipment selection and operation, how to
                      eliminate or overcome common error sources, and specific
                      applications. Training courses from independent training companies
                      are preferred since they are not biased toward a single brand or
                      type of equipment.


                      [edit] Other imaging

                      Infrared light from the LED of an xbox 360 remote control as seen by
                      a digital camera.In infrared photography, infrared filters are used
                      to capture the near-infrared spectrum. Digital cameras often use
                      infrared blockers. Cheaper digital cameras and some camera phones
                      which do not have appropriate filters can "see" near-infrared,
                      appearing as a bright white color (try pointing a TV remote at your
                      digital camera). This is especially pronounced when taking pictures
                      of subjects near IR-bright areas (such as near a lamp), where the
                      resulting infrared interference can wash out the image. There is
                      also a technique called 'T-ray' imaging, which is imaging using far
                      infrared or terahertz radiation. Lack of bright sources makes
                      terahertz photography technically more challenging than most other
                      infrared imaging techniques. Recently T-ray imaging has been of
                      considerable interest due to a number of new developments such as
                      terahertz time-domain spectroscopy.

                      [edit] Heating
                      Infrared radiation can be used as a deliberate heating source. For
                      example it is used in infrared saunas to heat the occupants, and
                      also to remove ice from the wings of aircraft (de-icing). It is also
                      gaining popularity as a method of heating asphalt pavements in place
                      during new construction or in repair of damaged asphalt. Infrared
                      can be used in cooking and heating food as it predominantly heats
                      the opaque, absorbent objects, rather than the air around them.

                      Infrared heating is also becoming more popular in industrial
                      manufacturing processes, e.g. curing of coatings, forming of
                      plastics, annealing, plastic welding, print drying. In these
                      applications, infrared heaters replace convection ovens and contact
                      heating. Efficiency is achieved by matching the wavelength of the
                      infrared heater to the absorption characteristics of the material.


                      [edit] 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. Infrared communications are useful for indoor
                      use in areas of high population density. IR does not penetrate walls
                      and so does not interfere with other devices in adjoining rooms.
                      Infrared is the most common way for remote controls to command
                      appliances.

                      Free space optical communication using infrared lasers can be a
                      relatively inexpensive way to install a communications link in an
                      urban area operating at up to 4 gigabit/s, compared to the cost of
                      burying fiber optic cable.

                      Infrared lasers are used to provide the light for optical fiber
                      communications systems. Infrared light with a wavelength around
                      1,330 nm (least dispersion) or 1,550 nm (best transmission) are the
                      best choices for standard silica fibers.


                      [edit] Spectroscopy
                      Infrared vibrational spectroscopy (see also near infrared
                      spectroscopy) is a technique which can be used to identify molecules
                      by analysis of their constituent bonds. Each chemical bond in a
                      molecule vibrates at a frequency which is characteristic of that
                      bond. A group of atoms in a molecule (e.g. CH2) may have multiple
                      modes of oscillation caused by the stretching and bending motions of
                      the group as a whole. If an oscillation leads to a change in dipole
                      in the molecule, then it will absorb a photon which has the same
                      frequency. The vibrational frequencies of most molecules correspond
                      to the frequencies of infrared light. Typically, the technique is
                      used to study organic compounds using light radiation from 4000-400
                      cm-1, the mid-infrared. A spectrum of all the frequencies of
                      absorption in a sample is recorded. This can be used to gain
                      information about the sample composition in terms of chemical groups
                      present and also its purity (for example a wet sample will show a
                      broad O-H absorption around 3200cm-1).


                      [edit] Meteorology

                      IR Satellite picture taken 1315 Z on 15th October 2006. A frontal
                      system can be seen in the Gulf of Mexico with embedded Cumulonimbus
                      cloud. Shallower Cumulus and Stratocumulus can be seen off the
                      Eastern Seaboard.Weather satellites equipped with scanning
                      radiometers produce thermal or infrared images which can then enable
                      a trained analyst to determine cloud heights and types, to calculate
                      land and surface water temperatures, and to locate ocean surface
                      features. The scanning is typically in the range 10.3-12.5 µm (IR4
                      and IR5 channels).

                      High, cold ice cloud such as Cirrus or Cumulonimbus show up bright
                      white, lower warmer cloud such as Stratus or Stratocumulus show up
                      as grey with intermediate clouds shaded accordingly. Hot land
                      surfaces will show up as dark grey or black. One disadvantage of
                      infrared imagery is that low cloud such as stratus or fog can be a
                      similar temperature to the surrounding land or sea surface does not
                      show up. However using the difference in brightness of the IR4
                      channel (10.3-11.5 µm) and the near-infrared channel (1.58-1.64 µm),
                      low cloud can be distinguished, producing a fog satellite picture.
                      The main advantage of infrared is that images can be produced at
                      night, allowing a continuous sequence of weather to be studied.

                      These infrared pictures can depict ocean eddies or vortices and map
                      currents such as the Gulf Stream which are valuable to the shipping
                      industry. Fishermen and farmers are interested in knowing land and
                      water temperatures to protect their crops against frost or increase
                      their catch from the sea. Even El Niño phenomena can be spotted.
                      Using color-digitized techniques, the gray shaded thermal images can
                      be converted to color for easier identification of desired
                      information.


                      [edit] Climatology
                      In the field of climatology, atmospheric infrared radiation is
                      monitored to detect trends in the energy exchange between the earth
                      and the atmosphere. These trends provide information on long term
                      changes in the earth's climate. It is one of the primary parameters
                      studied in research into global warming together with solar
                      radiation.

                      A pyrgeometer is utilized in this field of research to perform
                      continuous outdoor measurements. This is a broadband infrared
                      radiometer with sensitivity for infrared radiation between
                      approximately 4.5µm and 50µm.


                      Example of a pyrgeometer. Model shown CGR 4. Picture courtesy of
                      Kipp & Zonen BV. http://www.kippzonen.com/pyrgeometer
                      [edit] Astronomy

                      The Spitzer Space Telescope is a dedicated infrared space
                      observatory currently in orbit around the Sun. (Note the black side
                      to the telescope, to maximize infrared radiation.) NASA image.Main
                      articles: infrared astronomy and far infrared astronomy
                      Astronomers observe objects in the infrared portion of the
                      electromagnetic spectrum using optical components, including
                      mirrors, lenses and solid state digital detectors. For this reason
                      it is classified as part of optical astronomy. To form an image, the
                      components of an infrared telescope need to be carefully shielded
                      from heat sources, and the detectors are chilled using liquid helium.

                      The sensitivity of Earth-based infrared telescopes is significantly
                      limited by water vapor in the atmosphere, which absorbs a portion of
                      the infrared radiation arriving from space outside of selected
                      atmospheric windows. This limitation can be partially alleviated by
                      placing the telescope observatory at a high altitude, or by carrying
                      the telescope aloft with a balloon or an aircraft. Space telescopes
                      do not suffer from this handicap, and so outer space is considered
                      the ideal location for infrared astronomy.

                      The infrared portion of the spectrum has several useful benefits for
                      astronomers. Cold, dark molecular clouds of gas and dust in our
                      galaxy will glow with radiated heat as they are irradiated by
                      imbedded stars. Infrared can also be used to detect protostars
                      before they begin to emit visible light. Stars emit a smaller
                      portion of their energy in the infrared spectrum, so nearby cool
                      objects such as planets can be more readily detected. (In the
                      visible light spectrum, the glare from the star will drown out the
                      reflected light from a planet.)

                      Infrared light is also useful for observing the cores of active
                      galaxies which are often cloaked in gas and dust. Distant galaxies
                      with a high redshift will have the peak portion of their spectrum
                      shifted toward longer wavelengths, so they are more readily observed
                      in the infrared.[2]


                      [edit] Art history and Archaeology

                      The Arnolfini Portrait by Jan van Eyck, National Gallery,
                      LondonInfra-red (as art historians call them) reflectograms are
                      taken of paintings to reveal underlying layers, in particular the
                      underdrawing or outline drawn to by the artist as a guide. This
                      often uses carbon black which shows up well in reflectograms, so
                      long as it has not also been used in the ground underlying the whole
                      painting. Art historians are looking to see if the visible layers of
                      paint differ from the under-drawing or layers in between - such
                      alterations are called pentimenti when made by the original artist.
                      This is very useful information in deciding whether a painting is
                      the prime version by the original artist or a copy, and whether it
                      has been altered by over-enthusiatic restoration work. Generally the
                      more pentimenti, the more likely a painting is to be the prime
                      version. It also gives useful insights into working practices. [2]

                      Among many other changes in the Arnolfini Portrait of 1434 (right),
                      his face was higher by about the height of his eye, hers was higher,
                      and her eyes looked more to the front. Each of his feet was
                      underdrawn in one position, painted in another, and then overpainted
                      in a third. These alterations are seen in infra-red reflectograms.[8]

                      Similar uses of infrared are made by archaeologists on various types
                      of objects, especially very old written documents such as the Dead
                      Sea Scrolls, the Roman works in the Villa of the Papyri, and the
                      Silk Road texts found in the Dunhuang Caves.[9] Carbon black used in
                      ink can show up extremely well.


                      [edit] Biological systems

                      Thermographic image of a snake eating a mouseThe pit viper is known
                      to have two infrared sensory pits on its head. There is controversy
                      over the exact thermal sensitivity of this biological infrared
                      detection system.[10][11]

                      Other organisms that actively employ thermo-receptors are
                      rattlesnakes (Crotalinae subfamily) and boas (Boidae family), the
                      Common Vampire Bat (Desmodus rotundus), a variety of jewel beetles
                      (Melanophila acuminata)[12], darkly pigmented butterflies
                      (Pachliopta aristolochiae and Troides rhadamathus plateni), and
                      possibly blood-sucking bugs (Triatoma infestans).[13]


                      [edit] The Earth as an infrared emitter
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                      The Earth's surface and the clouds absorb visible and invisible
                      radiation from the sun and re-emit much of the energy as infrared
                      back to the atmosphere. Certain substances in the atmosphere,
                      chiefly cloud droplets and water vapor, but also carbon dioxide,
                      methane, nitrous oxide, sulfur hexafluoride, and
                      chlorofluorocarbons, 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.


                      [edit] History of infrared science
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                      The discovery of infrared radiation is ascribed to William Herschel,
                      the astronomer, in the early 19th century. Herschel published his
                      results in 1800 before the UK Royal Society. 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. He was surprised at the result and called
                      them "Calorific Rays". The term 'Infrared' did not appear until late
                      in the 19th century.

                      Other important dates include:[5]

                      1835: Macedonio Melloni makes the first thermopile IR detector;
                      1859: Gustav Kirchhoff formulates the blackbody theorem E = J(T,n);
                      1873: Willoughby Smith discovers the photoconductivity of selenium;
                      1879: Stefan-Boltzmann law formulated empirically
                      1880s & 1890s: Lord Rayleigh and Wilhelm Wien both solve part of the
                      blackbody equation, but both solutions are approximations that "blow
                      up" out of their useful ranges. This problem was called the "UV
                      Catastrophe and Infrared Catastrophe".
                      1901: Max Planck published the blackbody equation and theorem. He
                      solved the problem by quantizing the allowable energy transitions.
                      Early 1900s: Albert Einstein develops the theory of the
                      photoelectric effect, determining the photon. Also William Coblentz
                      in spectroscopy and radiometry.
                      1917: Case develops thallous sulfide detector; British develop the
                      first infra-red search and track (IRST) in World War I and detect
                      aircraft at a range of one mile;
                      1935: Lead salts-early missile guidance in World War II;
                      1938: Teau Ta-predicted that the pyroelectric effect could be used
                      to detect infrared radiation.
                      1952: H. Welker discovers InSb;
                      1950s: Paul Kruse (at Honeywell) and Texas Instruments form infrared
                      images before 1955;
                      1950s and 1960s: Nomenclature and radiometric units defined by Fred
                      Nicodemenus, G.J. Zissis and R. Clark, Jones defines D*;
                      1958: W.D. Lawson (Royal Radar Establishment in Malvern) discovers
                      IR detection properties of HgCdTe;
                      1958: Falcon & Sidewinder missiles developed using infrared and the
                      first textbook on infrared sensors appears by Paul Kruse, et al.
                      1962: J. Cooper demonstrated pyroelectric detection;
                      1962: Kruse and ? Rodat advance HgCdTe; Signal Element and Linear
                      Arrays available;
                      1965: First IR Handbook; first commercial imagers (Barnes, Agema
                      {now part of FLIR Systems Inc.}; Richard Hudson's landmark text; F4
                      TRAM FLIR by Hughes; phenomenology pioneered by Fred Simmons and
                      A.T. Stair; U.S. Army's night vision lab formed (now Night Vision
                      and Electronic Sensors Directorate (NVESD), and Rachets develops
                      detection, recognition and identification modeling there;
                      1970: ? Boyle & ? Smith propose CCD at Bell Labs for picture phone;
                      1972: Common module program started by NVESD;
                      1978: Pommernig & ? Francis fabricate IRCCDs; US Common Module leads
                      to a proliferation of IR Sensors in the U.S. military; commercial IR
                      companies formed (Inframetrics in Boston, MA and FLIR Systems Inc.
                      in Portland OR); Infrared imaging astronomy comes of age,
                      observatories planned, IRTF on Mauna Kea opened; 32 by 32 and 64 by
                      64 arrays are produced in InSb, HgCdTe and other materials.
                    • Ma. Elena Mediavilla
                      radiation is electromagnetic radiation whose wavelength is longer than that of visible light, but shorter than that of terahertz radiation and microwaves. The
                      Message 10 of 22 , Jul 3, 2008
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                        radiation is electromagnetic radiation whose wavelength is longer
                        than that of visible light, but shorter than that of terahertz
                        radiation and microwaves. The name means "below red" (from the Latin
                        infra, "below"), red being the color of visible light with the
                        longest wavelength. Infrared radiation has wavelengths between about
                        750 nm and 1 mm, spanning three orders of magnitude. Humans at
                        normal body temperature can radiate at a wavelength of 10 microns.[1]

                        Infrared imaging is used extensively for both military and civilian
                        purposes. Military applications include target acquisition,
                        surveillance, night vision, homing and tracking. Non-military uses
                        include thermal efficiency analysis, 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
                        cool objects such as planets, and to view highly red-shifted objects
                        from the early days of the universe.[2]

                        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. Infrared
                        spectroscopy examines absorption and transmission of photons in the
                        infrared energy range, based on their frequency and intensity.[3]
                      • dandrebchristopher
                        Infrared (IR) radiation is electromagnetic radiation whose wavelength is longer than that of visible light, but shorter than that of terahertz radiation and
                        Message 11 of 22 , Jul 14, 2008
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                          Infrared (IR) radiation is electromagnetic radiation whose wavelength
                          is longer than that of visible light, but shorter than that of
                          terahertz radiation and microwaves. The name means "below red" (from
                          the Latin infra, "below"), red being the color of visible light with
                          the longest wavelength. Infrared radiation has wavelengths between
                          about 750 nm and 1 mm, spanning three orders of magnitude. Humans at
                          normal body temperature can radiate at a wavelength of 10 microns.[1]

                          Infrared imaging is used extensively for both military and civilian
                          purposes. Military applications include target acquisition,
                          surveillance, night vision, homing and tracking. Non-military uses
                          include thermal efficiency analysis, remote temperature sensing,
                          short-ranged wireless communication, spectroscopy, weather
                          forecasting, and optical sensing for game controllers like the Wii
                          Remote. Infrared astronomy uses sensor-equipped telescopes to
                          penetrate dusty regions of space, such as molecular clouds; detect
                          cool objects such as planets, and to view highly red-shifted objects
                          from the early days of the universe.[2]

                          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. Infrared
                          spectroscopy examines absorption and transmission of photons in the
                          infrared energy range, based on their frequency and intensity.[3]
                        • aisonjay_salvaleon_10
                          Infrared (IR) radiation is electromagnetic radiation whose wavelength is longer than that of visible light, but shorter than that of terahertz radiation and
                          Message 12 of 22 , Jul 17, 2008
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                            Infrared (IR) radiation is electromagnetic radiation whose wavelength
                            is longer than that of visible light, but shorter than that of
                            terahertz radiation and microwaves. The name means "below red" (from
                            the Latin infra, "below"), red being the color of visible light with
                            the longest wavelength. Infrared radiation has wavelengths between
                            about 750 nm and 1 mm, spanning three orders of magnitude. Humans at
                            normal body temperature can radiate at a wavelength of 10 microns
                          • azzkicker_028
                            Infrared (IR) radiation is electromagnetic radiation whose wavelength is longer than that of visible light, but shorter than that of terahertz radiation and
                            Message 13 of 22 , Aug 9, 2008
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                              Infrared (IR) radiation is electromagnetic radiation whose wavelength
                              is longer than that of visible light, but shorter than that of
                              terahertz radiation and microwaves. The name means "below red" (from
                              the Latin infra, "below"), red being the color of visible light with
                              the longest wavelength. Infrared radiation has wavelengths between
                              about 750 nm and 1 mm, spanning three orders of magnitude. Humans at
                              normal body temperature can radiate at a wavelength of 10 micrometres.
                              [1]

                              Infrared imaging is used extensively for both military and civilian
                              purposes. Military applications include target acquisition,
                              surveillance, night vision, homing and tracking. Non-military uses
                              include thermal efficiency analysis, 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
                              cool objects such as planets, and to view highly red-shifted objects
                              from the early days of the universe.[2]

                              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. Infrared
                              spectroscopy examines absorption and transmission of photons in the
                              infrared energy range, based on their frequency and intensity
                            • stephanebacolcol_ivgold
                              For other uses, see Infrared (disambiguation). Image of two people in mid-infrared ( thermal ) light (false-color) Infrared (IR) radiation is electromagnetic
                              Message 14 of 22 , Oct 7, 2008
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                                For other uses, see Infrared (disambiguation).

                                Image of two people in mid-infrared ("thermal") light (false-color)
                                Infrared (IR) radiation is electromagnetic radiation whose wavelength
                                is longer than that of visible light, but shorter than that of
                                terahertz radiation and microwaves. The name means "below red" (from
                                the Latin infra, "below"), red being the color of visible light with
                                the longest wavelength. Infrared radiation has wavelengths between
                                about 750 nm and 1 mm, spanning three orders of magnitude. Humans at
                                normal body temperature can radiate at a wavelength of 10 micrometres
                              • merryannbastasa
                                Infrared (IR) radiation is electromagnetic radiation whose wavelength is longer than that of visible light (400-700 nm), but shorter than that of terahertz
                                Message 15 of 22 , Feb 2, 2009
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                                  Infrared (IR) radiation is electromagnetic radiation whose wavelength
                                  is longer than that of visible light (400-700 nm), but shorter than
                                  that of terahertz radiation (3-300 µm) and microwaves (~30,000 um).
                                  Infrared radiation spans roughly three orders of magnitude (750 nm and
                                  1000 µm).

                                  Direct sunlight has a luminous efficacy of about 93 lumens per watt of
                                  radiant flux, which includes infrared (47% share of the spectrum),
                                  visible (46%), and ultra-violet (only 7%) light. Bright sunlight
                                  provides luminance of approximately 100,000 candela per square meter at
                                  the Earth's surface.
                                • beltranpaoulyn
                                  Infrared (IR) radiation is electromagnetic radiation whose wavelength is longer than that of visible light (400-700 nm), but shorter than that of terahertz
                                  Message 16 of 22 , Aug 5, 2009
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                                    Infrared (IR) radiation is electromagnetic radiation whose wavelength is longer than that of visible light (400-700 nm), but shorter than that of terahertz radiation (100 µm - 1 mm) and microwaves (~30,000 µm). Infrared radiation spans roughly three orders of magnitude (750 nm and 100 µm).

                                    Direct sunlight has a luminous efficacy of about 93 lumens per watt of radiant flux, which includes infrared (47% share of the spectrum), visible (46%), and ultra-violet (only 6%) light. Bright sunlight provides luminance of approximately 100,000 candela per square meter at the Earth's surface.
                                  • Janica Viancci
                                    Infrared (IR) light is electromagnetic radiation with a wavelength longer than that of visible light, starting from the nominal edge of visible red light at
                                    Message 17 of 22 , Feb 11, 2011
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                                      Infrared (IR) light is electromagnetic radiation with a wavelength longer than that of visible light, starting from the nominal edge of visible red light at 0.7 micrometres, and extending conventionally to 300 micrometres. These wavelengths correspond to a frequency range of approximately 430 to 1 THz,[1] and include most of the thermal radiation emitted by objects near room temperature. Microscopically, IR light is typically emitted or absorbed by molecules when they change their rotational-vibrational movements.
                                      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.[2]
                                    • Shiela Mae
                                      Infrared (IR) light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at
                                      Message 18 of 22 , Jun 10, 2011
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                                        Infrared (IR) light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.7 micrometres, and extending conventionally to 300 micrometres. These wavelengths correspond to a frequency range of approximately 430 to 1 THz,[1] and include most of the thermal radiation emitted by objects near room temperature. Microscopically, IR light is typically emitted or absorbed by molecules when they change their rotational-vibrational movements.
                                        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.[2]
                                      • Shiela Mae
                                        Infrared (IR) light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at
                                        Message 19 of 22 , Jun 14, 2011
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                                          Infrared (IR) light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.7 micrometres, and extending conventionally to 300 micrometres. These wavelengths correspond to a frequency range of approximately 430 to 1 THz,[1] and include most of the thermal radiation emitted by objects near room temperature. Microscopically, IR light is typically emitted or absorbed by molecules when they change their rotational-vibrational movements.
                                        • zenith.duran23@ymail.com
                                          Infrared (IR) light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at
                                          Message 20 of 22 , Jun 19, 2011
                                          • 0 Attachment
                                            Infrared (IR) light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.7 micrometers, and extending conventionally to 300 micrometres. These wavelengths correspond to a frequency range of approximately 430 to 1 THz,[1] and include most of the thermal radiation emitted by objects near room temperature. Microscopically, IR light is typically emitted or absorbed by molecules when they change their rotational-vibrational movements.
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