Infrared: Difference between revisions

[[File:Ir girl.png|thumb|A [[false color|false-color]] image of two people taken in long-wavelength infrared (body-temperature thermal) radiation.]]

'''Infrared''' ('''IR'''; sometimes called '''infrared light''') is [[electromagnetic radiation]] (EMR) with [[wavelength]]s longer than that of [[visible light]] but shorter than [[Microwave|microwaves]]. The infrared [[spectral band]] begins with waves that are just longer than those of [[red]] light, (the longest waves in the [[visible spectrum]]), so IR is invisible to the human eye. IR is generally understood to include wavelengths from around {{Convert|750 [[nanometer|nm]] to 1000&nbsp;[[Micrometre|μm]] ([[FrequencyTHz|frequencies]] of 400&nbsp;[[terahertz (unit)lk=on|THz]]abbr=on}} to 300 [[Gigahertz{{Convert|1|mm|GHz]])|lk=on|abbr=on}}.<ref>{{Cite journal |last1=Vatansever |first1=Fatma |last2=Hamblin |first2=Michael R. |date=2012-01-01 |title=Far infrared radiation (FIR): Its biological effects and medical applications |journal=Photonics & Lasers in Medicine |volume=1 |issue=4 |pages=255–266 |doi=10.1515/plm-2012-0034 |issn=2193-0643 |pmc=3699878 |pmid=23833705}}</ref><ref>{{Cite book |url=http://www.intechopen.com/books/infrared-radiation |title=Infrared Radiation |date=2012-02-10 |publisher=InTech |isbn=978-953-51-0060-7 |editor-last=Morozhenko |editor-first=Vasyl |language=en |doi=10.5772/2031 |access-date=2023-11-15 |archive-date=2020-10-26 |archive-url=https://web.archive.org/web/20201026014729/https://www.intechopen.com/books/infrared-radiation |url-status=live }}</ref> IR is commonly divided between longer-wavelength thermal IR, emitted from terrestrial sources, and shorter-wavelength IR or near-IR, part of the [[sunlight|solar spectrum]].<ref name="IPCC AR4-SYR">{{cite web |url=https://ipcc.ch/pdf/assessment-report/ar4/syr/ar4_syr_appendix.pdf |title=IPCC AR4 SYR Appendix Glossary |access-date=2008-12-14 |url-status=dead |archive-url=https://web.archive.org/web/20181117121314/http://www.ipcc.ch/pdf/assessment-report/ar4/syr/ar4_syr_appendix.pdf |archive-date=2018-11-17}}</ref> Longer IR wavelengths (30–100&nbsp;μm) are sometimes included as part of the [[terahertz radiation]] band.<ref>{{cite book |last=Rogalski|first=Antoni |title=Infrared and terahertz detectors |date=2019 |publisher=[[CRC Press]] |location=Boca Raton, FL |isbn=9781315271330 |page=929 |edition=3rd}}</ref> Almost all [[black-body radiation]] from objects near [[room temperature]] is in the IR band. As a form of electromagnetic radiation, IR carries [[energy]] and [[momentum]], exerts [[radiation pressure]], and has properties corresponding to [[wave–particle duality|both]] those of a [[wave]] and of a [[subatomic particle|particle]], the [[photon]].

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. [[Infrared astronomy]] uses sensor-equipped [[telescope]]s to penetrate dusty regions of space such as [[molecular cloud]]s, to detect objects such as [[planet]]s, and to view highly [[red-shift]]ed objects from the early days of the [[universe]].<ref name="ir_astronomy">{{cite web |url=http://www.ipac.caltech.edu/Outreach/Edu/importance.html |title=IR Astronomy: Overview |publisher=NASA Infrared Astronomy and Processing Center |access-date=2006-10-30 |url-status=dead |archive-url=https://web.archive.org/web/20061208151300/http://www.ipac.caltech.edu/Outreach/Edu/importance.html |archive-date=2006-12-08 }}</ref> Infrared thermal-imaging cameras are used to detect heat loss in insulated systems, to observe changing blood flow in the skin, to assist firefighting, and to detect the overheating of electrical components.<ref>{{Cite web|last=Chilton|first=Alexander|date=2013-10-07|title=The Working Principle and Key Applications of Infrared Sensors|url=https://www.azosensors.com/article.aspx?ArticleID=339|access-date=2020-07-11|website=AZoSensors|language=en|archive-date=2020-07-11|archive-url=https://web.archive.org/web/20200711215350/https://www.azosensors.com/article.aspx?ArticleID=339|url-status=live}}</ref> Military and civilian applications include [[target acquisition]], [[surveillance]], [[night vision]], [[homing (missile guidance)|homing]], and tracking. Humans at normal body temperature radiate chiefly at wavelengths around 10&nbsp;μm. Non-military uses include [[thermal efficiency]] analysis, environmental monitoring, industrial facility inspections, detection of [[grow-ops]], remote temperature sensing, short-range [[wireless communication]], [[spectroscopy]], and [[weather forecasting]].

|+ [[ElectromagneticPosition spectrum|Lightin comparison]]the electromagnetic spectrum<ref>{{cite book|ref=Haynes|editor=Haynes, William M.|year=2011|title= CRC Handbook of Chemistry and Physics |edition=92nd|publisher= CRC Press|isbn=978-1-4398-5511-9|page=10.233}}</ref>

[[Sunlight]], at an effective temperature of 5,780&nbsp;[[Kelvin|K]] (5,510&nbsp;°C, 9,940&nbsp;°F), is composed of near-thermal-spectrum radiation that is slightly more than half infrared. At [[zenith]], sunlight provides an [[irradiance]] of just over 1&nbsp;[[kilowatt|kW]] per square meter at sea level. Of this energy, 527 W is infrared radiation, 445 W is visible light, and 32 W is [[ultraviolet]] radiation.<ref>{{cite web |url=http://rredc.nrel.gov/solar/spectra/am1.5/ |title=Reference Solar Spectral Irradiance: Air Mass 1.5 |access-date=2009-11-12 |archive-date=2019-05-12 |archive-url=https://web.archive.org/web/20190512190812/https://rredc.nrel.gov/solar//spectra/am1.5/ |url-status=live }}</ref> Nearly all the infrared radiation in sunlight is near infrared, shorter than 4 μm.

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.<ref>{{Cite web|url=https://www.e-education.psu.edu/astro801/content/l3_p5.html|title = Blackbody Radiation &#124; Astronomy 801: Planets, Stars, Galaxies, and the Universe|access-date=2019-02-12|archive-date=2019-05-01|archive-url=https://web.archive.org/web/20190501191803/https://www.e-education.psu.edu/astro801/content/l3_p5.html|url-status=live}}</ref>

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&nbsp;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 evenEven IR at wavelengths up to 1,050&nbsp;nm from pulsed lasers can be seen by humans under certain conditions.<ref name="Sliney1976">{{cite journal| last1=Sliney | first1=David H. | last2=Wangemann | first2=Robert T. | last3=Franks | first3=James K. | last4 =Wolbarsht | first4=Myron L. | year=1976 | title=Visual sensitivity of the eye to infrared laser radiation | journal=[[Journal of the Optical Society of America]] | volume=66 | issue=4 | pages=339–341 | doi=10.1364/JOSA.66.000339 | pmid=1262982 | quote=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. | bibcode=1976JOSA...66..339S }}</ref><ref name="LynchLivingston2001">{{cite book|last1=Lynch|first1=David K.|last2=Livingston|first2=William Charles|title=Color and Light in Nature|url=https://books.google.com/books?id=4Abp5FdhskAC&pg=PA231|access-date=12 October 2013|edition=2nd|year=2001|publisher=Cambridge University Press|location=Cambridge, UK|isbn=978-0-521-77504-5|page=231|quote=Limits of the eye's overall range of sensitivity extends from about 310 to 1,050 nanometers|archive-date=29 May 2024|archive-url=https://web.archive.org/web/20240529134755/https://books.google.com/books?id=4Abp5FdhskAC&pg=PA231#v=onepage&q&f=false|url-status=live}}</ref><ref name="Saidman1933">{{cite journal | last1=Saidman | first1=Jean | date=15 May 1933 | title=Sur la visibilité de l'ultraviolet jusqu'à la longueur d'onde 3130 | trans-title=The visibility of the ultraviolet to the wave length of 3130 | journal=[[Comptes rendus de l'Académie des sciences]] | volume=196 | pages=1537–9 | language=fr | url=http://visualiseur.bnf.fr/ark:/12148/bpt6k3148d | access-date=3 July 2014 | archive-date=24 October 2013 | archive-url=https://web.archive.org/web/20131024092515/http://visualiseur.bnf.fr/ark:/12148/bpt6k3148d | url-status=live }}</ref>

A commonly used subdivision scheme is:<ref name="Byrnes">{{Cite book|last=Byrnes |first=James |title=Unexploded Ordnance Detection and Mitigation |publisher=Springer |year=2009 |pages=21–22 |isbn=978-1-4020-9252-7|bibcode=2009uodm.book.....B }}</ref><ref name="RP-photonics">{{cite web |title=Infrared Light |url=https://www.rp-photonics.com/infrared_light.html |website=RP Photonics Encyclopedia |publisher=RP Photonics |access-date=20 July 2021 |archive-date=1 August 2021 |archive-url=https://web.archive.org/web/20210801132547/https://www.rp-photonics.com/infrared_light.html |url-status=live }}</ref>

! Temperature{{efn-lr|name=†|Temperatures of black bodies for which spectral peaks fall at the given wavelengths, according to the wavelength form of [[Wien's displacement law]]<ref>{{cite web|title=Peaks of Blackbody Radiation Intensity|url=http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/wien3.html|access-date=27 July 2016|archive-date=18 March 2011|archive-url=https://web.archive.org/web/20110318195600/http://hyperphysics.phy-astr.gsu.edu/Hbase/quantum/wien3.html|url-status=live}}</ref>}}

| 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 [[Infraredinfrared signature]] of the target aircraft, typically the jet engine exhaust plume. This region is also known as thermal infrared.

| 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, or moon, or an infrared illuminator. This region is also called the "thermal infrared".

! Abbreviation

! Wavelength

! Frequency

| IR-A || {{val|780&nbsp;nm |– 1,400&nbsp;|1400|u=nm<br}} />(0.78&nbsp;μm – 1.4&nbsp;μm) || {{val|215&nbsp;THz |– 430&nbsp;|384|u=THz}}

| IR-B || 1,400&nbsp;nm {{val|1400|– 3,000&nbsp;|3000|u=nm<br}} />(1.4&nbsp;μm – 3&nbsp;μm)|| {{val|100&nbsp;THz |– |215&nbsp;|u=THz}}

| IR-C || {{val|3,000&nbsp;nm |–|1000|u=μm}} 1&nbsp;mm<br />(3&nbsp;μm – 1,000&nbsp;μm)|| 300&nbsp;GHz {{val|0.3|– |100&nbsp;|u=THz}}

|align="left"| Near-Infraredinfrared

|align="left"| Mid-Infraredinfrared

|align="left"| Far-Infraredinfrared

|align="left"| Near-Infraredinfrared

| style="text-align:center;"| {{val|0.7 to |–|2.5&nbsp;|u=μm}}

|align="left"| Mid-Infraredinfrared

| style="text-align:center;"| {{val|3 to |–|25&nbsp;|u=μm}}

|align="left"| Far-Infraredinfrared

| style="text-align:center;"| above {{val|25&nbsp;|u=μm.}}

These divisions are not precise and can vary depending on the publication. The three regions are used for observation of different temperature ranges,<ref>{{CitationCite web needed|title=Near, Mid and Far-Infrared |url=https://www.icc.dur.ac.uk/~tt/Lectures/Galaxies/Images/Infrared/Regions/irregions.html |access-date=December2024-03-28 |website=www.icc.dur.ac.uk |archive-date=2024-03-28 |archive-url=https://web.archive.org/web/20240328203215/https://www.icc.dur.ac.uk/~tt/Lectures/Galaxies/Images/Infrared/Regions/irregions.html |url-status=live 2020}},</ref> and hence different environments in space.

The C-band is the dominant band for long-distance [[telecommunicationtelecommunications network]] networkss. The S and L bands are based on less well established technology, and are not as widely deployed.

[[File:Active-Infrared-Night-Vision.jpg|thumb|Active-infrared night vision: the camera illuminates the scene at infrared wavelengths invisible to the [[human eye]]. Despite a dark back-lit scene, active-infrared night vision delivers identifying details, as seen on the display monitor.]] Infrared is used in night vision equipment when there is insufficient visible light to see.<ref name="how night vision works">{{cite web |title=How Night Vision Works |publisher=American Technologies Network Corporation |url=http://www.atncorp.com/HowNightVisionWorks |access-date=2007-08-12 |archive-date=2015-08-24 |archive-url=https://web.archive.org/web/20150824223644/http://www.atncorp.com/hownightvisionworks |url-status=live }}</ref> [[Night vision devices]] operate through a process involving the conversion of ambient light photons into electrons that are then amplified by a chemical and electrical process and then converted back into visible light.<ref name="how night vision works"/> Infrared light sources can be used to augment the available ambient light for conversion by night vision devices, increasing in-the-dark visibility without actually using a visible light source.<ref name="how night vision works"/>

Thermal infrared hyperspectral imaging can be similarly performed using a [[thermographic camera]], with the fundamental difference that each pixel contains a full LWIR spectrum. Consequently, chemical identification of the object can be performed without a need for an external light source such as the Sun or the Moon. Such cameras are typically applied for geological measurements, outdoor surveillance and [[UAV]] applications.<ref name="Frost&Sullivan Specim Owl">Frost&Sullivan, Technical Insights, Aerospace&Defence (Feb 2011): [http://www.frost.com/prod/servlet/segment-toc.pag?segid=D870-00-48-00-00&ctxixpLink=FcmCtx3&ctxixpLabel=FcmCtx4 World First Thermal Hyperspectral Camera for Unmanned Aerial Vehicles] {{Webarchive|url=https://web.archive.org/web/20120310214352/http://www.frost.com/prod/servlet/segment-toc.pag?segid=D870-00-48-00-00&ctxixpLink=FcmCtx3&ctxixpLabel=FcmCtx4 |date=2012-03-10 }}.</ref>

Infrared tracking, also known as infrared homing, refers to a [[Passive homing|passive missile guidance system]], which uses the [[light emission|emission]] from a target of electromagnetic radiation in the infrared part of the spectrum to track it. Missiles that use infrared seeking are often referred to as "heat-seekers" since infrared (IR) is just below the visible spectrum of light in frequency and is radiated strongly by hot bodies. Many objects such as people, vehicle engines, and aircraft generate and retain heat, and as such, are especially visible in the infrared wavelengths of light compared to objects in the background.<ref>{{cite journal|author1=Mahulikar, S.P. |author2=Sonawane, H.R. |author3=Rao, G.A.|year=2007|title=Infrared signature studies of aerospace vehicles|journal=Progress in Aerospace Sciences|volume=43|issue=7–8|pages= 218–245|url=http://dspace.library.iitb.ac.in/xmlui/bitstream/handle/10054/613/5740.pdf|doi=10.1016/j.paerosci.2007.06.002|bibcode = 2007PrAeS..43..218M |citeseerx=10.1.1.456.9135 |access-date=2013-04-12|archive-date=2021-03-04|archive-url=https://web.archive.org/web/20210304165104/http://dspace.library.iitb.ac.in/xmlui/bitstream/handle/10054/613/5740.pdf|url-status=live}}</ref>

A variety of technologies or proposed technologies take advantage of infrared emissions to cool buildings or other systems. The LWIR (8–15&nbsp;μm) region is especially useful since some radiation at these wavelengths can escape into space through the atmosphere's [[infrared window]]. This is how [[passive daytime radiative cooling]] (PDRC) surfaces are able to achieve sub-ambient cooling temperatures under direct solar intensity, enhancing terrestrial [[heat flow]] to outer space with zero [[Efficient energy use|energy consumption]] or [[pollution]].<ref name=":5">{{Cite journal |last1=Chen |first1=Meijie |last2=Pang |first2=Dan |last3=Chen |first3=Xingyu |last4=Yan |first4=Hongjie |last5=Yang |first5=Yuan |title=Passive daytime radiative cooling: Fundamentals, material designs, and applications |journal=EcoMat |year=2022 |volume=4 |issue=1 |doi=10.1002/eom2.12153 |s2cid=240331557 |quote=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. |doi-access=free }}</ref><ref name=":023">{{Cite journal |last=Munday |first=Jeremy |date=2019 |title=Tackling Climate Change through Radiative Cooling |journal=Joule |volume=3 |issue=9 |pages=2057–2060 |doi=10.1016/j.joule.2019.07.010 |s2cid=201590290 |quote=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. |doi-access=free |bibcode=2019Joule...3.2057M }}</ref> PDRC surfaces minimizemaximize shortwave [[solar reflectance]] to lessen heat gain while maintaining strong longwave infrared (LWIR) [[thermal radiation]] [[heat transfer]].<ref name=":1">{{Cite journal |last1=Wang |first1=Tong |last2=Wu |first2=Yi |last3=Shi |first3=Lan |last4=Hu |first4=Xinhua |last5=Chen |first5=Min |last6=Wu |first6=Limin |date=2021 |title=A structural polymer for highly efficient all-day passive radiative cooling |journal=Nature Communications |volume=12 |issue=365 |page=365 |doi=10.1038/s41467-020-20646-7 |pmid=33446648 |pmc=7809060 |quote=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. }}</ref><ref name=":4422">{{Cite journal |last1=Zevenhovena |first1=Ron |last2=Fält |first2=Martin |date=June 2018 |title=Radiative cooling through the atmospheric window: A third, less intrusive geoengineering approach |url=https://www.sciencedirect.com/science/article/abs/pii/S0360544218304936 |journal=Energy |volume=152 |page=27 |doi=10.1016/j.energy.2018.03.084 |bibcode=2018Ene...152...27Z |quote= |via=Elsevier Science Direct |access-date=2022-10-13 |archive-date=2022-10-12 |archive-url=https://web.archive.org/web/20221012211516/https://www.sciencedirect.com/science/article/abs/pii/S0360544218304936 |url-status=live }}</ref> When imagined on a worldwide scale, this cooling method has been proposed as a way to slow and even reverse [[global warming]], with some estimates proposing a global surface area coverage of 1-2% to balance global heat fluxes.<ref name=":032">{{Cite journal |last=Munday |first=Jeremy |date=2019 |title=Tackling Climate Change through Radiative Cooling |journal=Joule |volume=3 |issue=9 |pages=2057–2060 |doi=10.1016/j.joule.2019.07.010 |s2cid=201590290 |quote=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. |doi-access=free |bibcode=2019Joule...3.2057M }}</ref><ref name=":442">{{Cite journal |last1=Zevenhovena |first1=Ron |last2=Fält |first2=Martin |date=June 2018 |title=Radiative cooling through the atmospheric window: A third, less intrusive geoengineering approach |url=https://www.sciencedirect.com/science/article/abs/pii/S0360544218304936 |journal=Energy |volume=152 |pages=27–33 |doi=10.1016/j.energy.2018.03.084 |bibcode=2018Ene...152...27Z |quote=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. |via=Elsevier Science Direct |access-date=2022-10-13 |archive-date=2022-10-12 |archive-url=https://web.archive.org/web/20221012211516/https://www.sciencedirect.com/science/article/abs/pii/S0360544218304936 |url-status=live }}</ref>

[[Free space optical communication]] using infrared [[laser]]s 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, except for the radiation damage. "Since the eye cannot detect IR, blinking or closing the eyes to help prevent or reduce damage may not happen."<ref>[http://www.ishn.com/articles/94815-dangers-of-overexposure-to-ultraviolet-infrared-and-high-energy-visible-light Dangers of Overexposure to ultraviolet, infrared and high-energy visible light | 2013-01-03] {{Webarchive|url=https://web.archive.org/web/20160816163547/http://www.ishn.com/articles/94815-dangers-of-overexposure-to-ultraviolet-infrared-and-high-energy-visible-light |date=2016-08-16 }}. ISHN. Retrieved on 2017-04-26.</ref>

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.<ref>[http://colourlex.com/project/ir-reflectography/ Infrared reflectography in analysis of paintings] {{Webarchive|url=https://web.archive.org/web/20151222133807/http://colourlex.com/project/ir-reflectography/ |date=2015-12-22 }} at ColourLex.</ref> Notable examples are [[Picasso]]'s ''[[Woman Ironing]]'' and ''[[Blue Room (Picasso)|Blue Room]]'', where in both cases a portrait of a man has been made visible under the painting as it is known today.

The [[Crotalinae|pit viper]] has a pair of infrared sensory pits on its head. There is uncertainty regarding the exact thermal sensitivity of this biological infrared detection system.<ref>{{Cite journal |title=Thermal Modeling of Snake Infrared Reception: Evidence for Limited Detection Range |journal=Journal of Theoretical Biology |volume=209 |issue=2 |pages=201–211 |year=2001 |doi=10.1006/jtbi.2000.2256 |pmid=11401462 |last1=Jones |first1=B.S. |last2=Lynn |first2=W.F. |last3=Stone |first3=M.O. |bibcode=2001JThBi.209..201J |url=https://zenodo.org/record/1229918 |access-date=2019-09-06 |archive-date=2020-03-17 |archive-url=https://web.archive.org/web/20200317210006/https://zenodo.org/record/1229918 |url-status=live }}</ref><ref>{{Cite journal|title=Biological Thermal Detection: Micromechanical and Microthermal Properties of Biological Infrared Receptors |journal=Biomacromolecules |volume=3 |issue=1 |pages=106–115 |year=2002 |doi=10.1021/bm015591f |pmid=11866562|last1=Gorbunov|first1=V.|last2=Fuchigami|first2=N.|last3=Stone|first3=M.|last4=Grace|first4=M.|last5=Tsukruk|first5=V. V.|s2cid=21737304 }}</ref>

Other organisms that have thermoreceptive organs are pythons (family [[Pythonidae]]), some boas (family [[Boidae]]), the [[Common Vampire Bat]] (''Desmodus rotundus''), a variety of [[jewel beetle]]s (''[[Melanophila acuminata]]''),<ref name=Evans>{{Cite journal|last=Evans |first=W.G. |title=Infrared receptors in ''Melanophila acuminata'' De Geer |journal=Nature |volume=202 |page=211 |year=1966 |doi=10.1038/202211a0|pmid=14156319 |bibcode = 1964Natur.202..211E |issue=4928|s2cid=2553265 |doi-access=free }}</ref> darkly pigmented butterflies (''[[Pachliopta aristolochiae]]'' and ''[[Troides rhadamantus plateni]]''), and possibly blood-sucking bugs (''[[Triatoma infestans]]'').<ref name=":0">{{Cite journal |title=Biological infrared imaging and sensing |journal=Micrometre |year=2002 |volume=33 |issue=2 |pages=211–225 |doi=10.1016/S0968-4328(01)00010-5 |pmid=11567889 |last1=Campbell |first1=Angela L. |last2=Naik |first2=Rajesh R. |last3=Sowards |first3=Laura |last4=Stone |first4=Morley O. |url=https://zenodo.org/record/1260182 |access-date=2019-06-13 |archive-date=2020-03-17 |archive-url=https://web.archive.org/web/20200317150323/https://zenodo.org/record/1260182 |url-status=live }}</ref> By detecting the heat that their prey emits, [[Pit viper|crotaline]] and [[Booidea|boid snakes]] identify and capture their prey using their [[Infrared sensing in snakes|IR-sensitive pit organs]]. Comparably, IR-sensitive pits on the [[Common vampire bat|Common Vampire Bat]] (''Desmodus rotundus'') aid in the identification of blood-rich regions on its warm-blooded victim. The jewel beetle, ''[[Melanophila acuminata]]'', locates [[Wildfire|forest fires]] via infrared pit organs, where on recently burnt trees, they deposit their eggs. [[Thermoreceptor|Thermoreceptors]] on the wings and antennae of butterflies with dark pigmentation, such ''[[Pachliopta aristolochiae]]'' and ''[[Troides rhadamantus plateni]]'', shield them from heat damage as they sunbathe in the sun. Additionally, it's hypothesised that thermoreceptors let bloodsucking bugs (''[[Triatoma infestans]]'') locate their [[warm-blooded]] victims by sensing their body heat.<ref name=":0" />

Although near-infrared vision (780–1,000&nbsp;nm) has long been deemed impossible due to noise in visual pigments,<ref name="Meuthen et al.">{{Cite journal|title=Visual prey detection by near-infrared cues in a fish|journal=Naturwissenschaften |year=2012 |doi=10.1007/s00114-012-0980-7|last1=Meuthen|first1=Denis|last2=Rick|first2=Ingolf P.|last3=Thünken|first3=Timo|last4=Baldauf|first4=Sebastian A.|volume=99|issue=12|pages=1063–6|pmid=23086394|bibcode = 2012NW.....99.1063M |s2cid=4512517 }}</ref> sensation of near-infrared light was reported in the common carp and in three cichlid species.<ref name="Meuthen et al." /><ref>{{Cite journal|title= Postural control in tilapia under microgravity and the near infrared irradiated conditions |author1=Endo, M. |author2=Kobayashi R. |author3=Ariga, K. |author4=Yoshizaki, G. |author5=Takeuchi, T. |journal= Nippon Suisan Gakkaishi |volume=68 |pages=887–892| year=2002|doi= 10.2331/suisan.68.887|issue= 6 |doi-access=free }}</ref><ref>{{Cite journal|title= Sensitivity of tilapia to infrared light measured using a rotating striped drum differs between two strains |author1=Kobayashi R. |author2=Endo, M. |author3=Yoshizaki, G. |author4=Takeuchi, T. |journal= Nippon Suisan Gakkaishi |volume=68 |pages=646–651| year=2002|doi= 10.2331/suisan.68.646|issue= 5 |doi-access=free }}</ref><ref>{{Cite journal|title= The eyes of the common carp and Nile tilapia are sensitive to near-infrared |doi=10.1111/j.1444-2906.2005.00971.x |journal= Fisheries Science |volume=71 |pages=350–355| year=2005|last1= Matsumoto|first1= Taro|last2= Kawamura|first2= Gunzo|issue= 2 |bibcode=2005FisSc..71..350M |s2cid=24556470 }}</ref><ref name="Shcherbakov et al.">{{Cite journal|title= Near-infrared orientation of Mozambique tilapia ''Oreochromis mossambicus'' |journal= Zoology |volume=115 |pages=233–238| year=2012 | doi=10.1016/j.zool.2012.01.005|last1= Shcherbakov|first1= Denis|last2= Knörzer|first2= Alexandra|last3= Hilbig|first3= Reinhard|last4= Haas|first4= Ulrich|last5= Blum|first5= Martin|issue= 4|pmid= 22770589|bibcode= 2012Zool..115..233S }}</ref> Fish use NIR to capture prey<ref name="Meuthen et al." /> and for phototactic swimming orientation.<ref name="Shcherbakov et al." /> NIR sensation in fish may be relevant under poor lighting conditions during twilight<ref name="Meuthen et al." /> and in turbid surface waters.<ref name="Shcherbakov et al." />

Near-infrared light, or [[photobiomodulation]], is used for treatment of chemotherapy-induced oral ulceration as well as wound healing. There is some work relating to anti-herpes virus treatment.<ref>{{cite journal | last1 = Hargate | first1 = G | title = A randomised double-blind study comparing the effect of 1072-nm light against placebo for the treatment of herpes labialis | journal = Clinical and Experimental Dermatology | volume = 31 | issue = 5 | pages = 638–41 | year = 2006 | pmid = 16780494 | doi = 10.1111/j.1365-2230.2006.02191.x | s2cid = 26977101 }}</ref> Research projects include work on central nervous system healing effects via cytochrome c oxidase upregulation and other possible mechanisms.<ref>{{cite journal | vauthors = Desmet KD, Paz DA, Corry JJ, Eells JT, Wong-Riley MT, Henry MM, Buchmann EV, Connelly MP, Dovi JV, Liang HL, Henshel DS, Yeager RL, Millsap DS, Lim J, Gould LJ, Das R, Jett M, Hodgson BD, Margolis D, Whelan HT | date = May 2006 | title = Clinical and experimental applications of NIR-LED photobiomodulation | journal = Photomedicine and Laser Surgery | volume = 24 | issue = 2 | pages = 121–8 | pmid = 16706690 | doi = 10.1089/pho.2006.24.121 | s2cid = 22442409 | url = https://epublications.marquette.edu/dentistry_fac/3 | access-date = 2019-06-13 | archive-date = 2020-03-16 | archive-url = https://web.archive.org/web/20200316014302/https://epublications.marquette.edu/dentistry_fac/3/ | url-status = live }}</ref>

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 [[Royal Society of London]]. Herschel used a [[Triangular prism (optics)|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".<ref>{{cite journal |last=Herschel |first=William |title=Experiments on the refrangibility of the invisible rays of the Sun |journal=Philosophical Transactions of the Royal Society of London |year=1800 |volume=90 |pages=284–292 |url=https://babel.hathitrust.org/cgi/pt?id=pst.000054592520;view=1up;seq=358 |jstor=107057 |doi=10.1098/rstl.1800.0015 |doi-access=free |access-date=2018-04-11 |archive-date=2021-02-04 |archive-url=https://web.archive.org/web/20210204133019/https://babel.hathitrust.org/cgi/pt?id=pst.000054592520;view=1up;seq=358 |url-status=live }}</ref><ref>{{cite web |url=http://coolcosmos.ipac.caltech.edu/cosmic_classroom/classroom_activities/herschel_bio.html |title=Herschel Discovers Infrared Light |website=Coolcosmos.ipac.caltech.edu |access-date=2011-11-08 |url-status=dead |archive-url=https://web.archive.org/web/20120225094516/http://coolcosmos.ipac.caltech.edu/cosmic_classroom/classroom_activities/herschel_bio.html |archive-date=2012-02-25 }}</ref> The term "infrared" did not appear until late 19th century.<ref>In 1867, French physicist [[Edmond Becquerel]] coined the term {{lang|fr|infra-rouge}} (infra-red):

* {{cite book |last1=Becquerel |first1=Edmond |title=La Lumiere: Ses causes et ses effets |trans-title=Light: Its causes and effects |date=1867 |publisher=Didot Frères, Fils et Cie. |location=Paris, France |pages=141–145 |url=https://books.google.com/books?id=SyWP1zBJiv0C&pg=PA141 |language=fr }}

* {{cite journal |last1=de Saint-Florent |title=Photography in natural colours |journal=The Photographic News |date=10 April 1874 |volume=18 |pages=175–176 |url=https://babel.hathitrust.org/cgi/pt?id=nyp.33433060399015;view=1up;seq=188 |access-date=15 April 2018 |archive-date=5 February 2021 |archive-url=https://web.archive.org/web/20210205123314/https://babel.hathitrust.org/cgi/pt?id=nyp.33433060399015;view=1up;seq=188 |url-status=live }} From p. 176: "As to the infra-red rays, they may be absorbed by means of a weak solution of sulphate of copper, ..."

* {{cite journal |last1=Rosenberg |first1=Gary |title=Letter to the Editors: Infrared dating |journal=American Scientist |date=2012 |volume=100 |issue=5 |page=355 |url=https://www.americanscientist.org/article/infrared-dating |access-date=2018-04-15 |archive-date=2018-04-15 |archive-url=https://web.archive.org/web/20180415124833/https://www.americanscientist.org/article/infrared-dating |url-status=live }}</ref> An [[Pictet's experiment|earlier experiment in 1790]] by [[Marc-Auguste Pictet]] demonstrated the reflection and focusing of radiant heat via mirrors in the absence of visible light.<ref>{{Cite book |last=Chang |first=Hasok |title=Inventing temperature: measurement and scientific progress |date=2007 |publisher=Oxford University Press |isbn=978-0-19-533738-9 |edition=1. issued as paperback |series=Oxford studies in philosophy of science |location=Oxford |pages=166–167}}</ref>

* {{cite journal |last1=Nobili |first1=Leopoldo |title=Description d'un thermo-multiplicateur ou thermoscope électrique |journal=Bibliothèque Universelle |date=1830 |volume=44 |pages=225–234 |url=https://babel.hathitrust.org/cgi/pt?id=pst.000052859885;view=1up;seq=237 |trans-title=Description of a thermo-multiplier or electric thermoscope |language=fr |access-date=2018-04-12 |archive-date=2021-02-24 |archive-url=https://web.archive.org/web/20210224141602/https://babel.hathitrust.org/cgi/pt?id=pst.000052859885;view=1up;seq=237 |url-status=live }}

* {{cite journal |last1=Nobili |last2=Melloni |title=Recherches sur plusieurs phénomènes calorifiques entreprises au moyen du thermo-multiplicateur |journal=Annales de Chimie et de Physique |date=1831 |volume=48 |pages=198–218 |url=https://babel.hathitrust.org/cgi/pt?id=uva.x002487856;view=1up;seq=202 |series=2nd series |trans-title=Investigations of several heat phenomena undertaken via a thermo-multiplier |language=fr |access-date=2018-04-12 |archive-date=2021-02-05 |archive-url=https://web.archive.org/web/20210205123013/https://babel.hathitrust.org/cgi/pt?id=uva.x002487856;view=1up;seq=202 |url-status=live }}

* {{cite book |last1=Vollmer |first1=Michael |last2=Möllmann |first2=Klaus-Peter |title=Infrared Thermal Imaging: Fundamentals, Research and Applications |date=2010 |publisher=Wiley-VCH |location=Berlin, Germany |pages=1–67 |edition=2nd |url=https://books.google.com/books?id=ClU_DwAAQBAJ&pg=SA1-PA67 |isbn=9783527693290 }}</ref>

* 1840: [[John Herschel]] produces the first thermal image, called a [[thermogram]].<ref>{{cite journal |last1=Herschel |first1=John F.&nbsp;W. |title=On chemical action of rays of solar spectrum on preparation of silver and other substances both metallic and nonmetallic and on some photographic processes |journal=Philosophical Transactions of the Royal Society of London |date=1840 |volume=130 |pages=1–59 |url=https://babel.hathitrust.org/cgi/pt?id=pst.000054592933;view=1up;seq=47 |bibcode=1840RSPT..130....1H |doi=10.1098/rstl.1840.0002 |s2cid=98119765 |access-date=2018-04-09 |archive-date=2021-02-05 |archive-url=https://web.archive.org/web/20210205123249/https://babel.hathitrust.org/cgi/pt?id=pst.000054592933;view=1up;seq=47 |url-status=live }} 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, ... ".</ref>

* {{cite journal |last1=Kirchhoff |title=Ueber den Zusammenhang von Emission und Absorption von Licht und Warme |journal=Monatsberichte der Königlich-Preussischen Akademie der Wissenschaften zu Berlin (Monthly Reports of the Royal Prussian Academy of Philosophy in Berlin) |date=1859 |pages=783–787 |url=https://babel.hathitrust.org/cgi/pt?id=mdp.39015049219333;view=1up;seq=811 |trans-title=On the relation between emission and absorption of light and heat |language=de |access-date=2018-04-10 |archive-date=2020-09-25 |archive-url=https://web.archive.org/web/20200925004705/https://babel.hathitrust.org/cgi/pt?id=mdp.39015049219333;view=1up;seq=811 |url-status=live }}

* {{cite journal |last1=Kirchhoff |first1=G. |title=Ueber das Verhältnis zwischen dem Emissionsvermögen und dem Absorptionsvermögen der Körper für Wärme und Licht |journal=Annalen der Physik und Chemie |date=1860 |volume=109 |issue=2 |pages=275–301 |url=https://babel.hathitrust.org/cgi/pt?id=umn.31951d00326548g;view=1up;seq=291 |trans-title=On the relation between bodies' emission capacity and absorption capacity for heat and light |language=de |bibcode=1860AnP...185..275K |doi=10.1002/andp.18601850205 |doi-access=free |access-date=2018-04-10 |archive-date=2020-09-01 |archive-url=https://web.archive.org/web/20200901105728/https://babel.hathitrust.org/cgi/pt?id=umn.31951d00326548g;view=1up;seq=291 |url-status=live }}

* English translation: {{cite journal |last1=Kirchhoff |first1=G. |title=On the relation between the radiating and absorbing powers of different bodies for light and heat |journal=Philosophical Magazine |date=1860 |volume=20 |pages=1–21 |url=https://babel.hathitrust.org/cgi/pt?id=pst.000068485634;view=1up;seq=19 |series=4th series |access-date=2018-04-11 |archive-date=2021-02-05 |archive-url=https://web.archive.org/web/20210205123215/https://babel.hathitrust.org/cgi/pt?id=pst.000068485634;view=1up;seq=19 |url-status=live }}</ref>

* {{cite journal |last1=Smith |first1=Willoughby |title=The action of light on selenium |journal=Journal of the Society of Telegraph Engineers |date=1873 |volume=2 |issue=4 |pages=31–33 |url=https://babel.hathitrust.org/cgi/pt?id=uiug.30112007449892;view=1up;seq=67 |doi=10.1049/jste-1.1873.0023 |access-date=2018-04-09 |archive-date=2021-01-03 |archive-url=https://web.archive.org/web/20210103112531/https://babel.hathitrust.org/cgi/pt?id=uiug.30112007449892;view=1up;seq=67 |url-status=live }}

* {{cite journal |last1=Smith |first1=Willoughby |title=Effect of light on selenium during the passage of an electric current |journal=Nature |date=20 February 1873 |volume=7 |issue=173 |page=303 |url=https://babel.hathitrust.org/cgi/pt?id=uiug.30112007449892;view=1up;seq=67 |doi=10.1038/007303e0 |bibcode=1873Natur...7R.303. |doi-access=free |access-date=9 April 2018 |archive-date=3 January 2021 |archive-url=https://web.archive.org/web/20210103112531/https://babel.hathitrust.org/cgi/pt?id=uiug.30112007449892;view=1up;seq=67 |url-status=live }}</ref>

* {{cite journal |last1=Langley |first1=S.&nbsp;P. |title=The bolometer |journal=Proceedings of the American Metrological Society |date=1880 |volume=2 |pages=184–190 |url=https://babel.hathitrust.org/cgi/pt?id=nyp.33433090766035;view=1up;seq=282 |access-date=2018-04-09 |archive-date=2021-02-05 |archive-url=https://web.archive.org/web/20210205123346/https://babel.hathitrust.org/cgi/pt?id=nyp.33433090766035;view=1up;seq=282 |url-status=live }}

* {{cite journal |last1=Langley |first1=S.&nbsp;P. |title=The bolometer and radiant energy |journal=Proceedings of the American Academy of Arts and Sciences |date=1881 |volume=16 |pages=342–358 |url=https://babel.hathitrust.org/cgi/pt?id=hvd.32044106428089;view=1up;seq=360 |doi=10.2307/25138616 |jstor=25138616 |access-date=2018-04-09 |archive-date=2021-02-05 |archive-url=https://web.archive.org/web/20210205125622/https://babel.hathitrust.org/cgi/pt?id=hvd.32044106428089;view=1up;seq=360 |url-status=live }}</ref>

* 1879: [[Stefan–Boltzmann law]] formulated empirically that the power radiated by a blackbody is proportional to ''T''⁴.<ref>{{cite journal |last1=Stefan |first1=J. |title=Über die Beziehung zwischen der Wärmestrahlung und der Temperatur |journal=Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften [Wien]: Mathematisch-naturwissenschaftlichen Classe (Proceedings of the Imperial Academy of Philosophy [in Vienna]: Mathematical-scientific Class) |date=1879 |volume=79 |pages=391–428 |url=https://babel.hathitrust.org/cgi/pt?id=hvd.32044093294874;view=1up;seq=419 |trans-title=On the relation between heat radiation and temperature |language=de |access-date=2018-04-11 |archive-date=2019-04-02 |archive-url=https://web.archive.org/web/20190402030509/https://babel.hathitrust.org/cgi/pt?id=hvd.32044093294874;view=1up;seq=419 |url-status=live }}</ref>

* {{cite journal |last1=Wien |first1=Willy |title=Ueber die Energieverteilung im Emissionsspektrum eines schwarzen Körpers |journal=Annalen der Physik und Chemie |date=1896 |volume=58 |pages=662–669 |url=https://babel.hathitrust.org/cgi/pt?id=wu.89048352850;view=1up;seq=676 |series=3rd series |trans-title=On the energy distribution in the emission spectrum of a black body |language=de |access-date=2018-04-10 |archive-date=2021-02-24 |archive-url=https://web.archive.org/web/20210224221923/https://babel.hathitrust.org/cgi/pt?id=wu.89048352850;view=1up;seq=676 |url-status=live }}

* English translation: {{cite journal |last1=Wien |first1=Willy |title=On the division of energy in the emission-spectrum of a black body |journal=Philosophical Magazine |date=1897 |volume=43 |issue=262 |pages=214–220 |doi=10.1080/14786449708620983 |url=https://babel.hathitrust.org/cgi/pt?id=mdp.39015024088695;view=1up;seq=226 |series=5th series |access-date=2018-04-10 |archive-date=2021-02-05 |archive-url=https://web.archive.org/web/20210205132307/https://babel.hathitrust.org/cgi/pt?id=mdp.39015024088695;view=1up;seq=226 |url-status=live }}</ref>

* {{cite journal |last1=Planck |first1=M. |title=Ueber eine Verbesserung der Wien'schen Spectralgleichung |journal=Verhandlungen der Deutschen Physikalischen Gesellschaft |date=1900 |volume=2 |pages=202–204 |url=https://babel.hathitrust.org/cgi/pt?id=coo.31924056107224;view=1up;seq=516 |trans-title=On an improvement of Wien's spectral equation |language=de }}

* {{cite journal |last1=Planck |first1=M. |title=Zur Theorie des Gesetzes der Energieverteilung im Normalspectrum |journal=Verhandlungen der Deutschen Physikalischen Gesellschaft |date=1900 |volume=2 |pages=237–245 |url=https://babel.hathitrust.org/cgi/pt?id=coo.31924056107224;view=1up;seq=551 |trans-title=On the theory of the law of energy distribution in the normal spectrum |language=de |access-date=2018-04-10 |archive-date=2021-02-25 |archive-url=https://web.archive.org/web/20210225013229/https://babel.hathitrust.org/cgi/pt?id=coo.31924056107224;view=1up;seq=551 |url-status=live }}

* {{cite journal |last1=Planck |first1=Max |title=Ueber das Gesetz der Energieverteilung im Normalspectrum |journal=Annalen der Physik |date=1901 |volume=4 |issue=3 |pages=553–563 |url=https://babel.hathitrust.org/cgi/pt?id=coo.31924066378310;view=1up;seq=585 |series=4th series |trans-title=On the law of energy distribution in the normal spectrum |language=de |bibcode=1901AnP...309..553P |doi=10.1002/andp.19013090310 |doi-access=free |access-date=2018-04-10 |archive-date=2021-02-06 |archive-url=https://web.archive.org/web/20210206034106/https://babel.hathitrust.org/cgi/pt?id=coo.31924066378310;view=1up;seq=585 |url-status=live }}</ref>

* 1958: [[W.&nbsp;D. Lawson]] ([[Royal Radar Establishment]] in Malvern) discovered IR detection properties of [[Mercury cadmium telluride]] (HgCdTe).<ref name=Reine>{{cite journal|url=https://link.springer.com/content/pdf/10.1007/s11664-015-3737-1.pdf|title=Interview with Paul W. Kruse on the Early History of HgCdTe (1980)|author=Marion B. Reine|journal=Journal of Electronic Materials |year=2015|volume=44 |issue=9 |access-date=2020-01-07|doi=10.1007/s11664-015-3737-1|s2cid=95341284|archive-date=2020-07-30|archive-url=https://web.archive.org/web/20200730140413/https://link.springer.com/content/pdf/10.1007/s11664-015-3737-1.pdf|url-status=live}}</ref>

* 2013: On 14 February, researchers developed a [[neural implant]] that gives [[rat]]s the ability to sense infrared light, which for the first time provides [[Living creature|living creatures]] with new abilities, instead of simply replacing or augmenting existing abilities.<ref>{{cite magazine |url=https://www.wired.co.uk/news/archive/2013-02/14/implant-gives-rats-sixth-sense-for-infrared-light |title=Implant gives rats sixth sense for infrared light |magazine=Wired UK |date=14 February 2013 |access-date=14 February 2013 |archive-date=17 February 2013 |archive-url=https://web.archive.org/web/20130217055046/http://www.wired.co.uk/news/archive/2013-02/14/implant-gives-rats-sixth-sense-for-infrared-light |url-status=live }}</ref>

* [http://www.omega.com/literature/transactions/volume1/historical1.html Infrared: A Historical Perspective] {{Webarchive|url=https://web.archive.org/web/20070807034953/http://www.omega.com/literature/transactions/volume1/historical1.html |date=2007-08-07 }} (Omega Engineering)

* [http://www.irda.org/ Infrared Data Association] {{Webarchive|url=https://web.archive.org/web/20080522132313/http://www.irda.org/ |date=2008-05-22 }}, a standards organization for infrared data interconnection

* [http://yengal-marumugam.blogspot.com/2011/06/sirc-part-i-basics.html SIRC Protocol ] {{Webarchive|url=https://web.archive.org/web/20111013110621/http://yengal-marumugam.blogspot.com/2011/06/sirc-part-i-basics.html |date=2011-10-13 }}

* [http://www.ocinside.de/html/modding/usb_ir_receiver/usb_ir_receiver.html How to build a USB infrared receiver to control PC's remotely] {{Webarchive|url=https://web.archive.org/web/20110719165527/http://www.ocinside.de/html/modding/usb_ir_receiver/usb_ir_receiver.html |date=2011-07-19 }}

* [http://www.thethermograpiclibrary.org/index.php/Cat%C3%A9gorie:Library The thermographic's library] {{Webarchive|url=https://web.archive.org/web/20130611022731/http://www.thethermograpiclibrary.org/index.php/Cat%C3%A9gorie:Library |date=2013-06-11 }}, collection of thermogram

* [http://colourlex.com/project/ir-reflectography/ Infrared reflectography in analysis of paintings] {{Webarchive|url=https://web.archive.org/web/20151222133807/http://colourlex.com/project/ir-reflectography/ |date=2015-12-22 }} at ColourLex

* Molly Faries, [http://www.nap.edu/read/11413/chapter/8 Techniques and Applications – Analytical Capabilities of Infrared Reflectography: An Art Historian s Perspective] {{Webarchive|url=https://web.archive.org/web/20151222152730/http://www.nap.edu/read/11413/chapter/8 |date=2015-12-22 }}, in Scientific Examination of Art: Modern Techniques in Conservation and Analysis, Sackler NAS Colloquium, 2005