Infrared
Infrared (IR; sometimes called infrared light) is
It was long known that fires emit invisible heat; in 1681 the pioneering experimenter Edme Mariotte showed that glass, though transparent to sunlight, obstructed radiant heat.[5][6] In 1800 the astronomer Sir William Herschel discovered that infrared radiation is a type of invisible radiation in the spectrum lower in energy than red light, by means of its effect on a thermometer.[7] Slightly more than half of the energy from the Sun was eventually found, through Herschel's studies, to arrive on Earth in the form of infrared. The balance between absorbed and emitted infrared radiation has an important effect on Earth's climate.
Infrared radiation is emitted or absorbed by
Infrared radiation is used in industrial, scientific, military, commercial, and medical applications. Night-vision devices using active near-infrared illumination allow people or animals to be observed without the observer being detected.
Definition and relationship to the electromagnetic spectrum
There is no universally accepted definition of the range of infrared radiation. Typically, it is taken to extend from the nominal red edge of the visible spectrum at 700 nm to 1 mm. This range of wavelengths corresponds to a
Name | Wavelength | Frequency (Hz) | Photon energy (eV) |
---|---|---|---|
Gamma ray | less than 10 pm | more than 30 EHz | more than 124 keV |
X-ray | 10 pm – 10 nm | 30 PHz – 30 EHz | 124 keV – 124 eV |
Ultraviolet | 10 nm – 400 nm | 750 THz – 30 PHz | 124 eV – 3.3 eV |
Visible |
400 nm – 700 nm | 430 THz – 750 THz | 3.3 eV – 1.7 eV |
Infrared | 700 nm – 1 mm | 300 GHz – 430 THz | 1.7 eV – 1.24 meV |
Microwave | 1 mm – 1 meter | 300 MHz – 300 GHz | 1.24 meV – 1.24 μeV |
Radio |
1 meter and more | 300 MHz and below | 1.24 μeV and below |
Nature
On the surface of Earth, at far lower temperatures than the surface of the Sun, some thermal radiation consists of infrared in the mid-infrared region, much longer than in sunlight. Black-body, or thermal, radiation is continuous: it radiates at all wavelengths. Of these natural thermal radiation processes, only lightning and natural fires are hot enough to produce much visible energy, and fires produce far more infrared than visible-light energy.[13]
Regions
In general, objects emit infrared radiation across a spectrum of wavelengths, but sometimes only a limited region of the spectrum is of interest because sensors usually collect radiation only within a specific bandwidth. Thermal infrared radiation also has a maximum emission wavelength, which is inversely proportional to the absolute temperature of object, in accordance with Wien's displacement law. The infrared band is often subdivided into smaller sections, although how the IR spectrum is thereby divided varies between different areas in which IR is employed.
Visible limit
Infrared radiation is generally considered to begin with wavelengths longer than visible by the human eye. There is no hard wavelength limit to what is visible, as the eye's sensitivity decreases rapidly but smoothly, for wavelengths exceeding about 700 nm. Therefore wavelengths just longer than that can be seen if they are sufficiently bright, though they may still be classified as infrared according to usual definitions. Light from a near-IR laser may thus appear dim red and can present a hazard since it may actually be quite bright. And even IR at wavelengths up to 1,050 nm from pulsed lasers can be seen by humans under certain conditions.[14][15][16]
Commonly used subdivision scheme
A commonly used subdivision scheme is:[17][18]
Division name | Abbreviation | Wavelength | Frequency | Photon energy | Temperature[i] | Characteristics |
---|---|---|---|---|---|---|
Near-infrared | NIR, IR-A DIN
|
0.75–1.4 μm
|
214–400 THz
|
886–1,653 meV
|
3,864–2,070 K (3,591–1,797 °C) |
Goes up to the wavelength of the first silica) medium. Image intensifiers are sensitive to this area of the spectrum; examples include night vision devices such as night vision goggles. Near-infrared spectroscopy is another common application.
|
Short-wavelength infrared | SWIR, IR-B DIN | 1.4–3 μm | 100–214 THz | 413–886 meV | 2,070–966 K (1,797–693 °C) |
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 (see transmission windows). |
Mid-wavelength infrared | MWIR, IR-C DIN; MidIR.[20] Also called intermediate infrared (IIR) | 3–8 μm | 37–100 THz | 155–413 meV | 966–362 K (693–89 °C) |
In guided missile technology the 3–5 μm portion of this band is the atmospheric window in which the seekers of passive IR 'heat seeking' missiles are designed to work, homing on to the Infrared signature of the target aircraft, typically the jet engine exhaust plume. This region is also known as thermal infrared. |
Long-wavelength infrared | LWIR, IR-C DIN | 8–15 μm | 20–37 THz | 83–155 meV | 362–193 K (89 – −80 °C) |
The "thermal imaging" region, in which sensors can obtain a completely passive image of objects only slightly higher in temperature than room temperature – for example, the human body – based on thermal emissions only and requiring no illumination such as the sun, moon, or infrared illuminator. This region is also called the "thermal infrared". |
Far-infrared | FIR | 15–1,000 μm | 0.3–20 THz | 1.2–83 meV | 193–3 K (−80.15 – −270.15 °C) |
(see also far-infrared laser and far-infrared) |
NIR and SWIR together is sometimes called "reflected infrared", whereas MWIR and LWIR is sometimes referred to as "thermal infrared".
CIE division scheme
The International Commission on Illumination (CIE) recommended the division of infrared radiation into the following three bands:[21][22]
Abbreviation | Wavelength | Frequency |
---|---|---|
IR-A | 780 nm – 1,400 nm (0.78 μm – 1.4 μm) |
215 THz – 430 THz |
IR-B | 1,400 nm – 3,000 nm (1.4 μm – 3 μm) |
100 THz – 215 THz |
IR-C | 3,000 nm – 1 mm (3 μm – 1,000 μm) |
300 GHz – 100 THz |
ISO 20473 scheme
ISO 20473 specifies the following scheme:[23]
Designation | Abbreviation | Wavelength |
---|---|---|
Near-infrared | NIR | 0.78–3 μm |
Mid-infrared | MIR | 3–50 μm |
Far-infrared | FIR | 50–1,000 μm |
Astronomy division scheme
Astronomers typically divide the infrared spectrum as follows:[24]
Designation | Abbreviation | Wavelength |
---|---|---|
Near-infrared | NIR | 0.7 to 2.5 μm |
Mid-infrared | MIR | 3 to 25 μm |
Far-infrared | FIR | above 25 μm. |
These divisions are not precise and can vary depending on the publication. The three regions are used for observation of different temperature ranges,[25] and hence different environments in space.
The most common photometric system used in astronomy allocates capital
Sensor response division scheme
A third scheme divides up the band based on the response of various detectors:[26]
- Near-infrared: from 0.7 to 1.0 μm (from the approximate end of the response of the human eye to that of silicon).
- Short-wave infrared: 1.0 to 3 μm (from the cut-off of silicon to that of the MWIR atmospheric window). InGaAs covers to about 1.8 μm; the less sensitive lead salts cover this region. Cryogenically cooled MCTdetectors can cover the region of 1.0–2.5 μm.
- Mid-wave infrared: 3 to 5 μm (defined by the atmospheric window and covered by indium antimonide, InSb and mercury cadmium telluride, HgCdTe, and partially by lead selenide, PbSe).
- Long-wave infrared: 8 to 12, or 7 to 14 μm (this is the atmospheric window covered by HgCdTe and microbolometers).
- Very-long wave infrared (VLWIR) (12 to about 30 μm, covered by doped silicon).
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 spectrum. 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's sensitivity starts around 950 nm and ends between 1,700 and 2,600 nm, depending on the specific configuration). No international standards for these specifications are currently available.
The onset of infrared is defined (according to different standards) at various values typically between 700 nm and 800 nm, but 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 longer wavelengths make insignificant contributions to scenes illuminated by common light sources. Particularly intense near-IR light (e.g., from
Telecommunication bands
In
Band | Descriptor | Wavelength range |
---|---|---|
O band | Original | 1,260–1,360 nm |
E band | Extended | 1,360–1,460 nm |
S band | Short wavelength | 1,460–1,530 nm |
C band | Conventional | 1,530–1,565 nm |
L band | Long wavelength | 1,565–1,625 nm |
U band | Ultralong wavelength | 1,625–1,675 nm |
The C-band is the dominant band for long-distance
Heat
Infrared radiation is popularly known as "heat radiation",[29] but light and electromagnetic waves of any frequency will heat surfaces that absorb them. Infrared light from the Sun accounts for 49%[30] of the heating of Earth, with 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. Objects at room temperature will emit radiation concentrated mostly in the 8 to 25 μm 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).[31]
The concept of emissivity is important in understanding the infrared emissions of objects. This is a property of a surface that describes how its thermal emissions deviate from the ideal of a black body. To further explain, two objects at the same physical temperature may not show the same infrared image if they have differing emissivity. For example, for any pre-set emissivity value, objects with higher emissivity will appear hotter, and those with a lower emissivity will appear cooler (assuming, as is often the case, that the surrounding environment is cooler than the objects being viewed). When an object has less than perfect emissivity, it obtains properties of reflectivity and/or transparency, and so the temperature of the surrounding environment is partially reflected by and/or transmitted through the object. If the object were in a hotter environment, then a lower emissivity object at the same temperature would likely appear to be hotter than a more emissive one. For that reason, incorrect selection of emissivity and not accounting for environmental temperatures will give inaccurate results when using infrared cameras and pyrometers.
Applications
This section needs additional citations for verification. (August 2007) |
Night vision
The use of infrared light and night vision devices should not be confused with
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
Hyperspectral imaging
A hyperspectral image is a "picture" containing continuous spectrum through a wide spectral range at each pixel. Hyperspectral imaging is gaining importance in the field of applied spectroscopy particularly with NIR, SWIR, MWIR, and LWIR spectral regions. Typical applications include biological, mineralogical, defence, and industrial measurements.
Thermal infrared hyperspectral imaging can be similarly performed using a
Other imaging
In
Tracking
Infrared tracking, also known as infrared homing, refers to a
Heating
Infrared radiation can be used as a deliberate heating source. For example, it is used in infrared saunas to heat the occupants. It may also be used in other heating applications, such as to remove ice from the wings of aircraft (de-icing).[37] Infrared radiation is used in cooking, known as broiling or grilling. One energy advantage is that the IR energy heats only opaque objects, such as food, 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, and print drying. In these applications, infrared heaters replace convection ovens and contact heating.
Cooling
A variety of technologies or proposed technologies take advantage of infrared emissions to cool buildings or other systems. The LWIR (8–15 μm) region is especially useful since some radiation at these wavelengths can escape into space through the atmosphere's
Communications
IR data transmission is also employed in short-range communication among computer peripherals and
Infrared lasers are used to provide the light for
IR data transmission of encoded audio versions of printed signs is being researched as an aid for visually impaired people through the
Spectroscopy
Infrared vibrational spectroscopy (see also near-infrared spectroscopy) is a technique that can be used to identify molecules by analysis of their constituent bonds. Each chemical bond in a molecule vibrates at a frequency 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 that 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 the mid-infrared, 4,000–400 cm−1. 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 3200 cm−1). The unit for expressing radiation in this application, cm−1, is the spectroscopic wavenumber. It is the frequency divided by the speed of light in vacuum.
Thin film metrology
In the semiconductor industry, infrared light can be used to characterize materials such as thin films and periodic trench structures. By measuring the reflectance of light from the surface of a semiconductor wafer, the index of refraction (n) and the extinction Coefficient (k) can be determined via the Forouhi–Bloomer dispersion equations. The reflectance from the infrared light can also be used to determine the critical dimension, depth, and sidewall angle of high aspect ratio trench structures.
Meteorology
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).
Clouds with high and cold tops, such as
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
The main water vapour channel at 6.40 to 7.08 μm can be imaged by some weather satellites and shows the amount of moisture in the atmosphere.
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 Earth's climate. It is one of the primary parameters studied in research into
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 4.5 μm and 50 μm.
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
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
Cleaning
Art conservation and analysis
Infrared reflectography[46] can be applied to paintings to reveal underlying layers in a non-destructive manner, in particular the artist's underdrawing or outline drawn as a guide. Art conservators use the technique to examine how the visible layers of paint differ from the underdrawing 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-enthusiastic restoration work. In general, the more pentimenti, the more likely a painting is to be the prime version. It also gives useful insights into working practices.[47] Reflectography often reveals the artist's use of carbon black, which shows up well in reflectograms, as long as it has not also been used in the ground underlying the whole painting.
Recent progress in the design of infrared-sensitive cameras makes it possible to discover and depict not only underpaintings and pentimenti, but entire paintings that were later overpainted by the artist.
Similar uses of infrared are made by conservators and scientists 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.[49] Carbon black used in ink can show up extremely well.
Biological systems
The
Other organisms that have thermoreceptive organs are pythons (family
Some fungi like Venturia inaequalis require near-infrared light for ejection.[54]
Although near-infrared vision (780–1,000 nm) has long been deemed impossible due to noise in visual pigments,[55] sensation of near-infrared light was reported in the common carp and in three cichlid species.[55][56][57][58][59] Fish use NIR to capture prey[55] and for phototactic swimming orientation.[59] NIR sensation in fish may be relevant under poor lighting conditions during twilight[55] and in turbid surface waters.[59]
Photobiomodulation
Near-infrared light, or
Health hazards
Strong infrared radiation in certain industry high-heat settings may be hazardous to the eyes, resulting in damage or blindness to the user. Since the radiation is invisible, special IR-proof goggles must be worn in such places.[62]
Scientific history
The discovery of infrared radiation is ascribed to
Other important dates include:[26]
- 1830: Leopoldo Nobili made the first thermopile IR detector.[67]
- 1840: thermogram.[68]
- 1860: Gustav Kirchhoff formulated the blackbody theorem .[69]
- 1873: Willoughby Smith discovered the photoconductivity of selenium.[70]
- 1878:
- 1879: Stefan–Boltzmann law formulated empirically that the power radiated by a blackbody is proportional to T4.[72]
- 1880s and 1890s: Lord Rayleigh and Wilhelm Wien solved part of the blackbody equation, but both solutions diverged in parts of the electromagnetic spectrum. This problem was called the "ultraviolet catastrophe and infrared catastrophe".[73]
- 1892: Willem Henri Julius published infrared spectra of 20 organic compounds measured with a bolometer in units of angular displacement.[74]
- 1901: Max Planck published the blackbody equation and theorem. He solved the problem by quantizing the allowable energy transitions.[75]
- 1905: Albert Einstein developed the theory of the photoelectric effect.[76]
- 1905–1908: William Coblentz published infrared spectra in units of wavelength (micrometers) for several chemical compounds in Investigations of Infra-Red Spectra.[77][78][79]
- 1917: thallous sulfide detector, which helped produce the first infrared search and trackdevice able to detect aircraft at a range of one mile (1.6 km).
- 1935: Lead salts – early missile guidance in World War II.
- 1938: Yeou Ta predicted that the pyroelectric effect could be used to detect infrared radiation.[80]
- 1945: The Zielgerät 1229 "Vampir" infrared weapon system was introduced as the first portable infrared device for military applications.
- 1952: Heinrich Welker grew synthetic InSb crystals.
- 1950s and 1960s: Nomenclature and radiometric units defined by Fred Nicodemenus, G. J. Zissis and R. Clark; Robert Clark Jones defined D*.
- 1958: W. D. Lawson (Royal Radar Establishment in Malvern) discovered IR detection properties of Mercury cadmium telluride (HgCdTe).[81]
- 1958: Falcon and Sidewinder missiles were developed using infrared technology.
- 1960s: Paul Kruse and his colleagues at Honeywell Research Center demonstrate the use of HgCdTe as an effective compound for infrared detection.[81]
- 1962: J. Cooper demonstrated pyroelectric detection.[82]
- 1964: W. G. Evans discovered infrared thermoreceptors in a pyrophile beetle.[52]
- 1965: First IR handbook; first commercial imagers (Night Vision and Electronic Sensors Directorate (NVESD)), and Rachetsdevelops detection, recognition and identification modeling there.
- 1970: picture phone.
- 1973: Common module program started by NVESD.[83]
- 1978: Infrared imaging astronomy came of age, observatories planned, IRTF on Mauna Kea opened; 32 × 32 and 64 × 64 arrays produced using InSb, HgCdTe and other materials.
- 2013: On 14 February, researchers developed a living creatures with new abilities, instead of simply replacing or augmenting existing abilities.[84]
See also
Notes
- ^ Temperatures of black bodies for which spectral peaks fall at the given wavelengths, according to the wavelength form of Wien's displacement law[19]
References
- PMID 23833705.
- ISBN 978-953-51-0060-7.
- ^ "IPCC AR4 SYR Appendix Glossary" (PDF). Archived from the original (PDF) on 2018-11-17. Retrieved 2008-12-14.
- ISBN 9781315271330.
- ^ Calel, Raphael (19 February 2014). "The Founding Fathers v. The Climate Change Skeptics". The Public Domain Review. Retrieved 16 September 2019.
- ^ Fleming, James R. (17 March 2008). "Climate Change and Anthropogenic Greenhouse Warming: A Selection of Key Articles, 1824–1995, with Interpretive Essays". National Science Digital Library Project Archive PALE:ClassicArticles. Retrieved 1 February 2022. Article 1: General remarks on the temperature of the earth and outer space.
- ISBN 1107024765.
- ^ Reusch, William (1999). "Infrared Spectroscopy". Michigan State University. Archived from the original on 2007-10-27. Retrieved 2006-10-27.
- ^ a b "IR Astronomy: Overview". NASA Infrared Astronomy and Processing Center. Archived from the original on 2006-12-08. Retrieved 2006-10-30.
- ^ Chilton, Alexander (2013-10-07). "The Working Principle and Key Applications of Infrared Sensors". AZoSensors. Retrieved 2020-07-11.
- ISBN 978-1-4398-5511-9.
- ^ "Reference Solar Spectral Irradiance: Air Mass 1.5". Retrieved 2009-11-12.
- ^ "Blackbody Radiation | Astronomy 801: Planets, Stars, Galaxies, and the Universe".
- PMID 1262982.
The foveal sensitivity to several near-infrared laser wavelengths was measured. It was found that the eye could respond to radiation at wavelengths at least as far as 1064 nm. A continuous 1064 nm laser source appeared red, but a 1060 nm pulsed laser source appeared green, which suggests the presence of second harmonic generation in the retina.
- ISBN 978-0-521-77504-5. Retrieved 12 October 2013.
Limits of the eye's overall range of sensitivity extends from about 310 to 1,050 nanometers
- Comptes rendus de l'Académie des sciences(in French). 196: 1537–9.
- ISBN 978-1-4020-9252-7.
- ^ "Infrared Light". RP Photonics Encyclopedia. RP Photonics. Retrieved 20 July 2021.
- ^ "Peaks of Blackbody Radiation Intensity". Retrieved 27 July 2016.
- R&D Magazine. August 14, 2012. rdmag.com. Retrieved September 8, 2012.
- ^ Henderson, Roy. "Wavelength considerations". Instituts für Umform- und Hochleistungs. Archived from the original on 2007-10-28. Retrieved 2007-10-18.
- ^ CIE (International Commission on Illumination). "infrared radiation IR radiation IRR". 17-21-004. Retrieved 18 October 2022.
- ^ ISO 20473:2007 – Optics and photonics – Spectral bands.
- ^ "Near, Mid and Far-Infrared". NASA IPAC. Archived from the original on 2012-05-29. Retrieved 2007-04-04.
- ^ "Near, Mid and Far-Infrared". www.icc.dur.ac.uk. Retrieved 2024-03-28.
- ^ ]
- PMID 20256359.
- S2CID 29838317.
- ISBN 978-0471743989.
- DOC) on 2009-03-18. Retrieved 2007-08-12.
- ^ McCreary, Jeremy (October 30, 2004). "Infrared (IR) basics for digital photographers-capturing the unseen (Sidebar: Black Body Radiation)". Digital Photography For What It's Worth. Archived from the original on 2008-12-18. Retrieved 2006-11-07.
- ^ a b c "How Night Vision Works". American Technologies Network Corporation. Retrieved 2007-08-12.
- ^ Bryant, Lynn (2007-06-11). "How does thermal imaging work? A closer look at what is behind this remarkable technology". Archived from the original on 2007-07-28. Retrieved 2007-08-12.
- ^ Holma, H., (May 2011), Thermische Hyperspektralbildgebung im langwelligen Infrarot Archived 2011-07-26 at the Wayback Machine, Photonik
- ^ Frost&Sullivan, Technical Insights, Aerospace&Defence (Feb 2011): World First Thermal Hyperspectral Camera for Unmanned Aerial Vehicles.
- .
- ^ White, Richard P. (2000) "Infrared deicing system for aircraft" U.S. patent 6,092,765
- S2CID 240331557.
Passive daytime radiative cooling (PDRC) dissipates terrestrial heat to the extremely cold outer space without using any energy input or producing pollution. It has the potential to simultaneously alleviate the two major problems of energy crisis and global warming.
- S2CID 201590290.
By covering the Earth with a small fraction of thermally emitting materials, the heat flow away from the Earth can be increased, and the net radiative flux can be reduced to zero (or even made negative), thus stabilizing (or cooling) the Earth.
- PMID 33446648.
Accordingly, designing and fabricating efficient PDRC with sufficiently high solar reflectance (𝜌¯solar) (λ ~ 0.3–2.5 μm) to minimize solar heat gain and simultaneously strong LWIR thermal emittance (ε¯LWIR) to maximize radiative heat loss is highly desirable. When the incoming radiative heat from the Sun is balanced by the outgoing radiative heat emission, the temperature of the Earth can reach its steady state.
- ^ Zevenhovena, Ron; Fält, Martin (June 2018). "Radiative cooling through the atmospheric window: A third, less intrusive geoengineering approach". Energy. 152 – via Elsevier Science Direct.
- S2CID 201590290.
If only 1%–2% of the Earth's surface were instead made to radiate at this rate rather than its current average value, the total heat fluxes into and away from the entire Earth would be balanced and warming would cease.
- ^ Zevenhovena, Ron; Fält, Martin (June 2018). "Radiative cooling through the atmospheric window: A third, less intrusive geoengineering approach". Energy. 152 – via Elsevier Science Direct.
With 100 W/m2 as a demonstrated passive cooling effect, a surface coverage of 0.3% would then be needed, or 1% of Earth's land mass surface. If half of it would be installed in urban, built areas which cover roughly 3% of the Earth's land mass, a 17% coverage would be needed there, with the remainder being installed in rural areas.
- ^ Dangers of Overexposure to ultraviolet, infrared and high-energy visible light | 2013-01-03. ISHN. Retrieved on 2017-04-26.
- ^ Digital ICE. kodak.com
- ^ "IR Reflectography for Non-destructive Analysis of Underdrawings in Art Objects". Sensors Unlimited, Inc. Archived from the original on 2008-12-08. Retrieved 2009-02-20.
- ^ "The Mass of Saint Gregory: Examining a Painting Using Infrared Reflectography". The Cleveland Museum of Art. Archived from the original on 2009-01-13. Retrieved 2009-02-20.
- ^ Infrared reflectography in analysis of paintings at ColourLex.
- ^ "International Dunhuang Project An Introduction to digital infrared photography and its application within IDP". Idp.bl.uk. Archived from the original on 2008-12-02. Retrieved 2011-11-08.
- PMID 11401462.
- S2CID 21737304.
- ^ S2CID 2553265.
- PMID 11567889.
- S2CID 4293713.
- ^ S2CID 4512517.
- .
- .
- S2CID 24556470.
- ^ PMID 22770589.
- S2CID 26977101.
- S2CID 22442409.
- ISBN 978-1-58115-204-3.
- JSTOR 107057.
- ^ "Herschel Discovers Infrared Light". Coolcosmos.ipac.caltech.edu. Archived from the original on 2012-02-25. Retrieved 2011-11-08.
- ^ In 1867, French physicist Edmond Becquerel coined the term infra-rouge (infra-red):
- Becquerel, Edmond (1867). La Lumiere: Ses causes et ses effets [Light: Its causes and effects] (in French). Paris, France: Didot Frères, Fils et Cie. pp. 141–145.
- de Saint-Florent (10 April 1874). "Photography in natural colours". The Photographic News. 18: 175–176. From p. 176: "As to the infra-red rays, they may be absorbed by means of a weak solution of sulphate of copper, ..."
- Rosenberg, Gary (2012). "Letter to the Editors: Infrared dating". American Scientist. 100 (5): 355.
- ISBN 978-0-19-533738-9.
- ^ See:
- Nobili, Leopoldo (1830). "Description d'un thermo-multiplicateur ou thermoscope électrique" [Description of a thermo-multiplier or electric thermoscope]. Bibliothèque Universelle (in French). 44: 225–234.
- Nobili; Melloni (1831). "Recherches sur plusieurs phénomènes calorifiques entreprises au moyen du thermo-multiplicateur" [Investigations of several heat phenomena undertaken via a thermo-multiplier]. Annales de Chimie et de Physique. 2nd series (in French). 48: 198–218.
- Vollmer, Michael; Möllmann, Klaus-Peter (2010). Infrared Thermal Imaging: Fundamentals, Research and Applications (2nd ed.). Berlin, Germany: Wiley-VCH. pp. 1–67. ISBN 9783527693290.
- S2CID 98119765. The term "thermograph" is coined on p. 51: " ... I have discovered a process by which the calorific rays in the solar spectrum are made to leave their impress on a surface properly prepared for the purpose, so as to form what may be called a thermograph of the spectrum, ... ".
- ^ See:
- Kirchhoff (1859). "Ueber den Zusammenhang von Emission und Absorption von Licht und Warme" [On the relation between emission and absorption of light and heat]. Monatsberichte der Königlich-Preussischen Akademie der Wissenschaften zu Berlin (Monthly Reports of the Royal Prussian Academy of Philosophy in Berlin) (in German): 783–787.
- Kirchhoff, G. (1860). "Ueber das Verhältnis zwischen dem Emissionsvermögen und dem Absorptionsvermögen der Körper für Wärme und Licht" [On the relation between bodies' emission capacity and absorption capacity for heat and light]. Annalen der Physik und Chemie (in German). 109 (2): 275–301.
- English translation: Kirchhoff, G. (1860). "On the relation between the radiating and absorbing powers of different bodies for light and heat". Philosophical Magazine. 4th series. 20: 1–21.
- ^ See:
- Smith, Willoughby (1873). "The action of light on selenium". Journal of the Society of Telegraph Engineers. 2 (4): 31–33. .
- Smith, Willoughby (20 February 1873). "Effect of light on selenium during the passage of an electric current". Nature. 7 (173): 303. doi:10.1038/007303e0
- ^ See:
- Langley, S. P. (1880). "The bolometer". Proceedings of the American Metrological Society. 2: 184–190.
- Langley, S. P. (1881). "The bolometer and radiant energy". Proceedings of the American Academy of Arts and Sciences. 16: 342–358. JSTOR 25138616.
- ^ Stefan, J. (1879). "Über die Beziehung zwischen der Wärmestrahlung und der Temperatur" [On the relation between heat radiation and temperature]. Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften [Wien]: Mathematisch-naturwissenschaftlichen Classe (Proceedings of the Imperial Academy of Philosophy [in Vienna]: Mathematical-scientific Class) (in German). 79: 391–428.
- ^ See:
- Wien, Willy (1896). "Ueber die Energieverteilung im Emissionsspektrum eines schwarzen Körpers" [On the energy distribution in the emission spectrum of a black body]. Annalen der Physik und Chemie. 3rd series (in German). 58: 662–669.
- English translation: Wien, Willy (1897). "On the division of energy in the emission-spectrum of a black body". Philosophical Magazine. 5th series. 43 (262): 214–220. .
- ^ Julius, Willem Henri (1892). Bolometrisch onderzoek van absorptiespectra (in Dutch). J. Müller.
- ^ See:
- Planck, M. (1900). "Ueber eine Verbesserung der Wien'schen Spectralgleichung" [On an improvement of Wien's spectral equation]. Verhandlungen der Deutschen Physikalischen Gesellschaft (in German). 2: 202–204.
- Planck, M. (1900). "Zur Theorie des Gesetzes der Energieverteilung im Normalspectrum" [On the theory of the law of energy distribution in the normal spectrum]. Verhandlungen der Deutschen Physikalischen Gesellschaft (in German). 2: 237–245.
- Planck, Max (1901). "Ueber das Gesetz der Energieverteilung im Normalspectrum" [On the law of energy distribution in the normal spectrum]. Annalen der Physik. 4th series (in German). 4 (3): 553–563.
- ^ See:
- Einstein, A. (1905). "Über einen die Erzeugung und Verwandlung des Lichtes betreffenden heuristischen Gesichtspunkt" [On heuristic viewpoint concerning the production and transformation of light]. Annalen der Physik. 4th series (in German). 17 (6): 132–148.
- English translation: Arons, A. B.; Peppard, M. B. (1965). "Einstein's proposal of the photon concept—a translation of the Annalen der Physik paper of 1905". American Journal of Physics. 33 (5): 367–374. S2CID 27091754. Available at Wayback Machine.
- ^ Coblentz, William Weber (1905). Investigations of Infra-red Spectra: Part I, II. Carnegie institution of Washington.
- ^ Coblentz, William Weber (1905). Investigations of Infra-red Spectra: Part III, IV. University of Michigan. Washington, D.C., Carnegie institution of Washington.
- ^ Coblentz, William Weber (August 1905). Investigations of Infra-red Spectra: Part V, VI, VII. University of California Libraries. Washington, D.C. : Carnegie Institution of Washington.
- ISBN 9783642546341. Retrieved 2020-01-07.
- ^ )
- .
- ^ "History of Army Night Vision". C5ISR Center. Retrieved 2020-01-07.[permanent dead link]
- ^ "Implant gives rats sixth sense for infrared light". Wired UK. 14 February 2013. Retrieved 14 February 2013.
External links
- Infrared: A Historical Perspective (Omega Engineering)
- Infrared Data Association, a standards organization for infrared data interconnection
- SIRC Protocol
- How to build a USB infrared receiver to control PC's remotely
- Infrared Waves: detailed explanation of infrared light. (NASA)
- Herschel's original paper from 1800 announcing the discovery of infrared light
- The thermographic's library, collection of thermogram
- Infrared reflectography in analysis of paintings at ColourLex
- Molly Faries, Techniques and Applications – Analytical Capabilities of Infrared Reflectography: An Art Historian s Perspective, in Scientific Examination of Art: Modern Techniques in Conservation and Analysis, Sackler NAS Colloquium, 2005