Editing Diffraction grating (section)

==Examples==
[[Image:Interference-colors.jpg|thumbnail|200px|The grooves of a compact disc can act as a grating and produce [[iridescent]] reflections.]]

Diffraction gratings are often used in [[monochromator]]s, [[spectrometer]]s, [[laser]]s, [[wavelength division multiplexing]] devices, optical [[Pulse compression|pulse compressing]] devices, [[interferometer]]s,<ref>{{Cite journal | doi=10.1364/OE.409185| title=Fully symmetric dispersionless stable transmission-grating Michelson interferometer| year=2020| last1=Kolesnichenko| first1=Pavel| last2=Wittenbecher| first2=Lukas| last3=Zigmantas| first3=Donatas| journal=Optics Express| volume=28| issue=25| pages=37752–37757| doi-access=free| pmid=33379604| bibcode=2020OExpr..2837752K}}</ref> and many other optical instruments.

Ordinary pressed CD and DVD media are every-day examples of diffraction gratings and can be used to demonstrate the effect by reflecting sunlight off them onto a white wall. This is a side effect of their manufacture, as one surface of a CD has many small pits in the plastic, arranged in a spiral; that surface has a thin layer of metal applied to make the pits more visible. The structure of a DVD is optically similar, although it may have more than one pitted surface, and all pitted surfaces are inside the disc.<ref>''Ambient Diagnostics'' by Yang Cai – CRC Press 2014 Page 267</ref><ref>{{Cite web |last1=Balachandran |first1=Rama |last2=Porter-Davis |first2=Karen |title=USING CDs AND DVDs AS DIFFRACTION GRATINGS |url=https://www.nnin.org/sites/default/files/files/Karen_Rama_USING_CDs_AND_DVDs_AS_DIFFRACTION_GRATINGS_0.pdf |access-date=3 November 2023 |website=National Nanotechnology Infrastructure Network}}</ref>

Due to the sensitivity to the refractive index of the media, diffraction grating can be used as sensor of fluid properties.<ref name="OL2014">{{cite journal|last1=Xu|first1=Zhida|last2=Han|first2=Kevin|last3=Khan|first3=Ibrahim|last4=Wang|first4=Xinhao|last5=Liu|first5=Logan|title=Liquid refractive index sensing independent of opacity using an optofluidic diffraction sensor|journal=Optics Letters|date=2014|volume=39|issue=20|pages=6082–6085|doi=10.1364/OL.39.006082|pmid=25361161|arxiv=1410.0903|bibcode=2014OptL...39.6082X|s2cid=5087241}}</ref>

In a standard pressed [[Gramophone record|vinyl record]] when viewed from a low angle perpendicular to the grooves, a similar but less defined effect to that in a CD/DVD is seen. This is due to viewing angle (less than the [[critical angle (optics)|critical angle]] of reflection of the black vinyl) and the path of the light being reflected due to this being changed by the grooves, leaving a rainbow relief pattern behind.

Diffraction gratings are also used to distribute evenly the [[frontlight]] of [[e-reader]]s such as the [[Nook Simple Touch|Nook Simple Touch with GlowLight]].<ref>{{cite web |title=Step 17 |date=2012 |work=Nook Simple Touch with GlowLight Teardown |publisher=iFixit |url=https://www.ifixit.com/Teardown/Nook+Simple+Touch+with+GlowLight+Teardown/9301}}</ref>

===Gratings from electronic components===

[[File:Diffraction from mobile phone.jpg|200px|thumb|Diffraction of a spotlight over a mobile phone]]

Some everyday electronic components contain fine and regular patterns, and as a result readily serve as diffraction gratings. For example, [[Charge-coupled device|CCD]] sensors from discarded mobile phones and cameras can be removed from the device. With a laser pointer, diffraction can reveal the spatial structure of the CCD sensors.<ref>{{cite journal|url=http://diog.webs.upv.es/publicaciones/pdfs/2014_AMJPHYS_82_256.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://diog.webs.upv.es/publicaciones/pdfs/2014_AMJPHYS_82_256.pdf |archive-date=2022-10-09 |url-status=live|last1=Barreiro |title=Diffraction by electronic components of everyday use|doi=10.1119/1.4830043|volume=82|issue=3|date=March 2014|journal=American Journal of Physics|pages=257–261|first1=Jesús J.|last2=Pons|first2=Amparo|last3=Barreiro|first3=Juan C.|last4=Castro-Palacio|first4=Juan C.|last5=Monsoriu|first5=Juan A.|bibcode=2014AmJPh..82..257B|hdl=10251/54288 |hdl-access=free}}</ref> This can be done for LCD or LED displays of smart phones as well. Because such displays are usually protected just by transparent casing, experiments can be done without damaging the phones. If accurate measurements are not intended, a spotlight can reveal the diffraction patterns.

===Natural gratings===
[[File:Iridescent biofilm on a fishtank.JPG|thumb|A [[biofilm]] on the surface of a fishtank produces diffraction grating effects when the bacteria are all evenly sized and spaced. Such phenomena are an example of [[Quetelet rings]].]]
[[Striated muscle]] is the most commonly found natural diffraction grating<ref>{{cite journal|last1=Baskin |title=Light diffraction study of single skeletal muscle fibers|pmc=1328609 |pmid=318066|doi=10.1016/S0006-3495(79)85158-9|volume=28|issue=1|date=October 1979|journal=Biophys. J.|pages=45–64|bibcode = 1979BpJ....28...45B |first1=R.J.|last2=Roos|first2=K.P.|last3=Yeh|first3=Y.}}</ref> and, this has helped physiologists in determining the structure of such muscle. Aside from this, the chemical structure of crystals can be thought of as diffraction gratings for types of electromagnetic radiation other than visible light, this is the basis for techniques such as [[X-ray crystallography]].

Most commonly confused with diffraction gratings are the [[iridescent]] colors of [[peacock]] feathers, [[mother-of-pearl]], and [[butterfly]] wings. Iridescence in birds,<ref name="stavenga">{{Cite journal | doi = 10.1016/j.matpr.2014.09.007| title = Thin Film and Multilayer Optics Cause Structural Colors of Many Insects and Birds| journal = Materials Today: Proceedings| volume = 1| pages = 109–121| year = 2014| last1 = Stavenga | first1 = D. G. | doi-access = free}}</ref> fish<ref>{{Cite journal | doi = 10.1073/pnas.1216282109| title = High levels of reflectivity and pointillist structural color in fish, cephalopods, and beetles| journal = Proceedings of the National Academy of Sciences| volume = 109| issue = 50| pages = E3387| year = 2012| last1 = Roberts | first1 = N. W.| last2 = Marshall | first2 = N. J.| last3 = Cronin | first3 = T. W.|bibcode = 2012PNAS..109E3387R | pmid=23132935 | pmc=3528518| doi-access = free}}</ref> and insects<ref name="stavenga"/><ref>{{Cite journal | doi = 10.1242/jeb.098673| title = Coloration principles of nymphaline butterflies - thin films, melanin, ommochromes and wing scale stacking| journal = Journal of Experimental Biology| volume = 217| issue = 12| pages = 2171–2180| year = 2014| last1 = Stavenga | first1 = D. G.| last2 = Leertouwer | first2 = H. L.| last3 = Wilts | first3 = B. D. | pmid=24675561| doi-access = free}}</ref> is often caused by [[thin-film interference]] rather than a diffraction grating. Diffraction produces the entire spectrum of colors as the viewing angle changes, whereas thin-film interference usually produces a much narrower range. The surfaces of flowers can also create a diffraction, but the cell structures in plants are usually too irregular to produce the fine slit geometry necessary for a diffraction grating.<ref>{{Cite journal | doi = 10.1111/nph.12808| pmid = 24713039| title = Iridescent flowers? Contribution of surface structures to optical signaling| url=https://www.researchgate.net/publication/261515138 | format=PDF| journal = New Phytologist| volume = 203| issue = 2| pages = 667–73| year = 2014| last1 = Van Der Kooi | first1 = C. J. | last2 = Wilts | first2 = B. D. | last3 = Leertouwer | first3 = H. L. | last4 = Staal | first4 = M. | last5 = Elzenga | first5 = J. T. M. | last6 = Stavenga | first6 = D. G. | doi-access = free | bibcode = 2014NewPh.203..667V}}</ref> The iridescence signal of flowers is thus only appreciable very locally and hence not visible to man and flower visiting insects.<ref>{{cite book |first=David W. |last=Lee |title=Nature's Palette: The Science of Plant Color |url=https://books.google.com/books?id=M3e5wyFJY-8C&pg=PA255 |date=2007 |publisher=University of Chicago Press |isbn=978-0-226-47105-1 |pages=255–6 }}</ref><ref>{{Cite journal | doi = 10.1111/nph.13066| pmid = 25243861| title = Is floral iridescence a biologically relevant cue in plant-pollinator signaling?| url=https://www.researchgate.net/publication/265912479| format = PDF| journal = New Phytologist| volume = 205| issue = 1| pages = 18–20| year = 2015| last1 = Van Der Kooi | first1 = C. J. | last2 = Dyer | first2 = A. G. | last3 = Stavenga | first3 = D. G. | doi-access = free| bibcode = 2015NewPh.205...18V}}</ref> However, natural gratings do occur in some invertebrate animals, like the [[Maratus|peacock spiders]],<ref>{{Cite journal|last1=Hsiung|first1=Bor-Kai|last2=Siddique|first2=Radwanul Hasan|last3=Stavenga|first3=Doekele G.|last4=Otto|first4=Jürgen C.|last5=Allen|first5=Michael C.|last6=Liu|first6=Ying|last7=Lu|first7=Yong-Feng|last8=Deheyn|first8=Dimitri D.|last9=Shawkey|first9=Matthew D.|date=22 December 2017|title=Rainbow peacock spiders inspire miniature super-iridescent optics|journal=Nature Communications|language=En|volume=8|issue=1|pages=2278|doi=10.1038/s41467-017-02451-x|pmid=29273708|pmc=5741626|issn=2041-1723|bibcode=2017NatCo...8.2278H}}</ref> the antennae of [[seed shrimp]], and have even been discovered in [[Burgess Shale type fauna|Burgess Shale fossils]].<ref>{{harvnb|Lee|2007|p=41}}</ref><ref>{{cite web |title=Colouring in the fossil past |date=15 March 2006 |work=News |publisher=Natural History Museum |url=http://www.nhm.ac.uk/about-us/news/2006/mar/news_7834.html |access-date=14 September 2010 |archive-url=https://web.archive.org/web/20100812044454/http://www.nhm.ac.uk/about-us/news/2006/mar/news_7834.html |archive-date=12 August 2010 |url-status=dead }}</ref>
 
Diffraction grating effects are sometimes seen in [[meteorology]]. [[Corona (optical phenomenon)|Diffraction coronas]] are colorful rings surrounding a source of light, such as the sun. These are usually observed much closer to the light source than [[halo (optical phenomenon)|halos]], and are caused by very fine particles, like water droplets, ice crystals, or smoke particles in a hazy sky. When the particles are all nearly the same size they diffract the incoming light at very specific angles. The exact angle depends on the size of the particles. Diffraction coronas are commonly observed around light sources, like candle flames or street lights, in the fog. [[Cloud iridescence]] is caused by diffraction, occurring along coronal rings when the particles in the clouds are all uniform in size.<ref>{{cite book |first=G. P. |last=Können |title=Polarized Light in Nature |url=https://archive.org/details/trent_0116300226960 |url-access=registration |year=1985 |publisher=Cambridge University Press |isbn=978-0-521-25862-3 |pages=[https://archive.org/details/trent_0116300226960/page/72 72]–73}}</ref>