Editing Diffraction grating (section)

{{short description|Optical component which splits light into several beams}}
{{more footnotes|date=December 2011}}
{{Use dmy dates|date=April 2024}}
[[Image:Diffraction grating.jpg|thumb|right|300px|A very large reflecting diffraction grating]]
[[File:An incandescent light-bulb viewed through a transmissive diffraction grating.jpg|thumb|An [[incandescent light bulb]] viewed through a diffractive effects filter.]] [[File:Diffraction grating demo.webm|thumb|Diffraction grating]]

In [[optics]], a '''diffraction grating''' is an optical [[grating]] with a periodic structure that [[diffraction|diffracts]] light, or another type of [[electromagnetic radiation]], into several beams traveling in different directions (i.e., different diffraction angles). The emerging coloration is a form of [[structural coloration]].<ref>{{Cite journal | doi = 10.1021/cr970080y| pmid = 11849015| title = Nano-Optics in the Biological World: Beetles, Butterflies, Birds, and Moths| journal = Chemical Reviews| volume = 99| issue = 7| pages = 1935–1962| year = 1999| last1 = Srinivasarao | first1 = M. }}</ref><ref>{{Cite journal | doi = 10.1088/0034-4885/71/7/076401| title = Physics of structural colors| journal = Reports on Progress in Physics| volume = 71| issue = 7| pages = 076401| year = 2008| last1 = Kinoshita | first1 = S. | last2 = Yoshioka | first2 = S. | last3 = Miyazaki | first3 = J. |bibcode = 2008RPPh...71g6401K | s2cid = 53068819}}</ref> The directions or diffraction angles of these beams depend on the wave (light) [[Angle of incidence (optics)|incident angle]] to the diffraction grating, the spacing or periodic distance between adjacent diffracting elements (e.g., parallel slits for a transmission grating) on the grating, and the [[wavelength]] of the incident light. The grating acts as a [[dispersion (optics)|dispersive]] element. Because of this, diffraction gratings are commonly used in [[monochromator]]s and [[spectrometer]]s, but other applications are also possible such as optical encoders for high-precision motion control<ref>{{Cite web|title=Optical Encoders|url=https://www.celeramotion.com/microe/support/technical-papers/pureprecision-optical-encoder-technology/|url-status=live|archive-url=https://web.archive.org/web/20200812035731/https://www.celeramotion.com/microe/support/technical-papers/pureprecision-optical-encoder-technology/ |access-date=2021-11-01|website=Celera motion|archive-date=12 August 2020 }}</ref> and [[wavefront]] measurement.<ref>{{Cite journal|last1=Paul M|first1=Blanchard|last2=David J|first2=Fisher|last3=Simon C|first3=Woods|last4=Alan H|first4=Greenaway|year=2000|title=Phase-diversity wave-front sensing with a distorted diffraction grating|url=https://www.osapublishing.org/viewmedia.cfm?r=1&rwjcode=ao&uri=ao-39-35-6649&html=true|journal=Applied Optics|volume=39|issue=35|pages=6649–6655|doi=10.1364/AO.39.006649 |pmid=18354679 |bibcode=2000ApOpt..39.6649B |url-access=subscription}}</ref><ref>{{Cite journal|last1=Hiroshi|first1=Ohba|last2=Shinichi|first2=Komatsu|year=1998|title=Wavefront Sensor Using a 2-Dimensional Diffraction Grating|url=https://iopscience.iop.org/article/10.1143/JJAP.37.3749|journal=Japanese Journal of Applied Physics|volume=37|issue=6B |pages=3749–3753|doi=10.1143/JJAP.37.3749 |bibcode=1998JaJAP..37.3749O |s2cid=121954416 |url-access=subscription}}</ref>

For typical applications, a [[reflection (optics)|reflective]] grating has ridges or ''rulings'' on its surface while a transmissive grating has transmissive or hollow slits on its surface.<ref>{{cite web |title=Introduction to Diffraction Grating |url=https://www.thorlabs.com/catalogpages/802.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://www.thorlabs.com/catalogpages/802.pdf |archive-date=2022-10-09 |url-status=live |publisher=Thor Labs |access-date=30 April 2020}}</ref> Such a grating modulates the amplitude of an incident wave to create a diffraction pattern. Some gratings modulate the phases of incident waves rather than the amplitude, and these types of gratings can be produced frequently by using [[holography]].<ref>{{cite journal |author1=AK Yetisen |author2=H Butt |author3=F da Cruz Vasconcellos |author4=Y Montelongo |author5=CAB Davidson |author6=J Blyth |author7=JB Carmody |author8=S Vignolini |author9=U Steiner |author10=JJ Baumberg |author11=TD Wilkinson |author12=CR Lowe |title=Light-Directed Writing of Chemically Tunable Narrow-Band Holographic Sensors |journal= Advanced Optical Materials |volume=2 |issue=3 |pages=250–254 |year=2013 |doi= 10.1002/adom.201300375 |s2cid=96257175 |url=https://www.repository.cam.ac.uk/handle/1810/293246 }}</ref>

[[James Gregory (astronomer and mathematician)|James Gregory]] (1638–1675) observed the diffraction patterns caused by a [[Feather#Coloration|bird feather]], which was effectively the first diffraction grating (in a natural form) to be discovered, about a year after [[Isaac Newton]]'s [[Prism (optics)|prism]] experiments.<ref>Letter from James Gregory to John Collins, dated [[1673#April–June|13 May 1673]].  Reprinted in: {{cite book |editor-first=Stephen Jordan |editor-last=Rigaud |title=Correspondence of Scientific Men of the Seventeenth Century … |publisher=Oxford University Press |year=1841 |pages=251–5 |volume=2}} especially [https://books.google.com/books?id=0h45L_66bcYC&pg=PA254 p. 254]</ref> The first human-made diffraction grating was made around 1785 by [[Philadelphia]] inventor [[David Rittenhouse]], who strung hairs between two finely threaded screws.<ref>{{cite journal |title=An optical problem, proposed by Mr. Hopkinson, and solved by Mr. Rittenhouse |journal=Transactions of the American Philosophical Society |volume=2 |pages=201–6 |year=1786 |url=https://books.google.com/books?id=OLgAAAAAYAAJ&pg=PA201 |doi=10.2307/1005186|jstor=1005186 |last1=Hopkinson |first1=F. |last2=Rittenhouse |first2=David |url-access=subscription }}</ref><ref>Thomas D. Cope (1932) [https://books.google.com/books?id=epgvIYkMiUIC&pg=PA377 "The Rittenhouse diffraction grating"].  Reprinted in: {{cite book |first=David |last=Rittenhouse |title=The Scientific Writings of David Rittenhouse |publisher=Arno Press |editor-first=Brooke |editor-last=Hindle |year=1980 |isbn= 9780405125683|pages=377–382 |url=https://books.google.com/books?id=epgvIYkMiUIC&pg=PA377|bibcode=1980swdr.book.....R }} (A reproduction of Rittenhouse's letter re his diffraction grating appears on pp. 369–374.)</ref> This was similar to notable German physicist [[Joseph von Fraunhofer]]'s wire diffraction grating in 1821.<ref>{{cite journal | last1 = Fraunhofer | first1 = Joseph von | year = 1821 | title = Neue Modifikation des Lichtes durch gegenseitige Einwirkung und Beugung der Strahlen, und Gesetze derselben |trans-title=New modification of light by the mutual influence and the diffraction of [light] rays, and the laws thereof | journal = Denkschriften der Königlichen Akademie der Wissenschaften zu München (Memoirs of the Royal Academy of Science in Munich) | volume = 8 | pages = 3–76 | url=https://books.google.com/books?id=k-EAAAAAYAAJ&pg=RA1-PA3}}</ref><ref>{{cite journal | last1 = Fraunhofer | first1 = Joseph von | year = 1823 | title = Kurzer Bericht von den Resultaten neuerer Versuche über die Gesetze des Lichtes, und die Theorie derselben |trans-title=Short account of the results of new experiments on the laws of light, and the theory thereof | url = http://gallica.bnf.fr/ark:/12148/bpt6k15083w/f353.image| journal = Annalen der Physik | volume = 74 | issue = 8| pages = 337–378 | doi=10.1002/andp.18230740802|bibcode = 1823AnP....74..337F }}</ref> The principles of diffraction were discovered by [[Thomas Young (scientist)|Thomas Young]]<ref>{{Cite journal|author = Thomas Young|date = 1 January 1804|url = https://books.google.com/books?id=7AZGAAAAMAAJ&pg=PA1|title=The Bakerian Lecture: Experiments and calculations relative to physical optics|journal=[[Philosophical Transactions of the Royal Society of London]]|volume = 94|pages = 1–16|doi = 10.1098/rstl.1804.0001|bibcode = 1804RSPT...94....1Y|s2cid = 110408369|doi-access = free|url-access = subscription}}.  (Note: This lecture was presented before the Royal Society on 24 November 1803.)</ref> and [[Augustin-Jean Fresnel]].<ref>Fresnel, Augustin-Jean (1816), "Mémoire sur la diffraction de la lumière" ("Memoir on the diffraction of light"), ''Annales de Chimie et de Physique'', vol.&nbsp;1, pp.&nbsp;239–81 (March 1816); reprinted as "Deuxième Mémoire…" ("Second Memoir…") in ''Oeuvres complètes d'Augustin Fresnel'', vol.&nbsp;1 (Paris: Imprimerie Impériale, 1866), [https://books.google.com/books?id=1l0_AAAAcAAJ&pg=PA89 pp.&nbsp;89–122]. (Revision of the [https://books.google.com/books?id=1l0_AAAAcAAJ&pg=PA9 "First&nbsp;Memoir"] submitted on 15&nbsp;October 1815.)</ref><ref>Fresnel, Augustin-Jean (1818), "Mémoire sur la diffraction de la lumière" ("Memoir on the diffraction of light"), deposited 29&nbsp;July 1818, "crowned" 15&nbsp;March 1819, published in ''Mémoires de l'Académie Royale des Sciences de l'Institut de France'', vol.&nbsp;{{serif|V}} (for 1821 & 1822, printed 1826), [https://books.google.com/books?id=zNo-AQAAMAAJ&pg=PA339 pp.&nbsp;339–475]; reprinted in ''Oeuvres complètes d'Augustin Fresnel'', vol.&nbsp;1 (Paris: Imprimerie Impériale, 1866), [https://books.google.com/books?id=1l0_AAAAcAAJ&pg=PA247 pp.&nbsp;247–364]; partly translated as [https://archive.org/details/wavetheoryofligh00crewrich/page/80 "Fresnel's prize memoir on the diffraction of light"], in H.{{nnbsp}}Crew (ed.), ''The Wave Theory of Light: Memoirs by Huygens, Young and Fresnel'', American Book Company, 1900, pp.&nbsp;81–144. (First published, as extracts only, in ''Annales de Chimie et de Physique'', vol.&nbsp;11 (1819), pp.&nbsp;[https://books.google.com/books?id=SSRQAAAAcAAJ&pg=PA246 246–96], [https://books.google.com/books?id=SSRQAAAAcAAJ&pg=PA337 337–78].)</ref> Using these principles, Fraunhofer was the first to use a diffraction grating to obtain [[spectral line|line spectra]] and the first to measure the wavelengths of spectral lines with a diffraction grating.

In the 1860s, state-of-the-art diffraction gratings with small groove period (''d'') were manufactured by [[Friedrich Adolph Nobert]] (1806–1881) in [[Greifswald]];<ref>{{Cite journal|last=Turner|first=G. L'E.|date=1967|title=The contributions to Science of Friedrich Adolph Nobert|journal=Bulletin of the Institute of Physics and the Physical Society|volume=18|issue=10|pages=338–348|doi=10.1088/0031-9112/18/10/006}}</ref> then the two Americans Lewis Morris Rutherfurd (1816–1892) and William B. Rogers (1804–1882) took over the lead.<ref>{{Cite journal|last=Warner|first=Deborah J.|date=1971|title=Lewis M. Rutherfurd: Pioneer Astronomical Photographer and Spectroscopist|journal=Technology and Culture|volume=12|issue=2|pages=190–216|doi=10.2307/3102525|jstor=3102525|s2cid=112109352 }}</ref><ref>{{Cite book|title=The Michelson Era in American Science 1870-1930|last=Warner|first=Deborah J.|publisher=American Institute of Physics|year=1988|location=New York|pages=2–12}}</ref> By the end of the 19th century, the concave gratings of [[Henry Augustus Rowland]] (1848–1901) were the best available.<ref>{{Cite journal|last=Hentschel|first=Klaus|date=1993|title=The Discovery of the Redshift of Solar Fraunhofer Lines by Rowland and Jewell in Baltimore around 1890 |url=https://elib.uni-stuttgart.de/bitstream/11682/5353/1/hen11.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://elib.uni-stuttgart.de/bitstream/11682/5353/1/hen11.pdf |archive-date=2022-10-09 |url-status=live|journal=Historical Studies in the Physical and Biological Sciences|volume=23|issue=2|pages=219–277|doi=10.2307/27757699|jstor=27757699}}</ref><ref>{{Cite book|title=The Command of Light: Rowland's School of Physics and the Spectrum|last=Sweetnam|first=George|publisher=American Philosophical Society|year=2000|isbn=978-08716-923-82|location=Philadelphia}}</ref>

A diffraction grating can create "[[rainbow]]" colors when it is illuminated by a wide-spectrum (e.g., continuous) light source. Rainbow-like colors from closely spaced narrow tracks on optical data storage disks such as CDs or DVDs are an example of light [[diffraction]] caused by diffraction gratings. A usual diffraction grating has parallel lines (It is true for 1-dimensional gratings, but 2 or 3-dimensional gratings are also possible and they have their applications such as wavefront measurement), while a CD has a spiral of finely spaced data tracks. Diffraction colors also appear when one looks at a bright point source through a translucent fine-pitch umbrella fabric covering. Decorative patterned plastic films based on reflective grating patches are inexpensive and commonplace. A similar color separation seen from thin layers of oil (or gasoline, etc.) on water, known as [[iridescence]], is not caused by diffraction from a grating but rather by [[thin film interference]] from the closely stacked transmissive layers.