Diffraction grating

A very large reflecting diffraction grating
An incandescent light bulb viewed through a diffractive effects filter.
Diffraction grating

In optics, a diffraction grating is an optical grating with a periodic structure that 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.[1][2] The directions or diffraction angles of these beams depend on the wave (light) 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 dispersive element. Because of this, diffraction gratings are commonly used in monochromators and spectrometers, but other applications are also possible such as optical encoders for high-precision motion control[3] and wavefront measurement.[4][5]

For typical applications, a reflective grating has ridges or rulings on its surface while a transmissive grating has transmissive or hollow slits on its surface.[6] 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.[7]

James Gregory (1638–1675) observed the diffraction patterns caused by a bird feather, which was effectively the first diffraction grating (in a natural form) to be discovered, about a year after Isaac Newton's prism experiments.[8] The first human-made diffraction grating was made around 1785 by Philadelphia inventor David Rittenhouse, who strung hairs between two finely threaded screws.[9][10] This was similar to notable German physicist Joseph von Fraunhofer's wire diffraction grating in 1821.[11][12] The principles of diffraction were discovered by Thomas Young[13] and Augustin-Jean Fresnel.[14][15] Using these principles, Fraunhofer was the first to use a diffraction grating to obtain 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;[16] then the two Americans Lewis Morris Rutherfurd (1816–1892) and William B. Rogers (1804–1882) took over the lead.[17][18] By the end of the 19th century, the concave gratings of Henry Augustus Rowland (1848–1901) were the best available.[19][20]

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.

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  2. ^ Kinoshita, S.; Yoshioka, S.; Miyazaki, J. (2008). "Physics of structural colors". Reports on Progress in Physics. 71 (7): 076401. Bibcode:2008RPPh...71g6401K. doi:10.1088/0034-4885/71/7/076401. S2CID 53068819.
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  8. ^ Letter from James Gregory to John Collins, dated 13 May 1673. Reprinted in: Rigaud, Stephen Jordan, ed. (1841). Correspondence of Scientific Men of the Seventeenth Century …. Vol. 2. Oxford University Press. pp. 251–5. especially p. 254
  9. ^ Hopkinson, F.; Rittenhouse, David (1786). "An optical problem, proposed by Mr. Hopkinson, and solved by Mr. Rittenhouse". Transactions of the American Philosophical Society. 2: 201–6. doi:10.2307/1005186. JSTOR 1005186.
  10. ^ Thomas D. Cope (1932) "The Rittenhouse diffraction grating". Reprinted in: Rittenhouse, David (1980). Hindle, Brooke (ed.). The Scientific Writings of David Rittenhouse. Arno Press. pp. 377–382. Bibcode:1980swdr.book.....R. ISBN 9780405125683. (A reproduction of Rittenhouse's letter re his diffraction grating appears on pp. 369–374.)
  11. ^ Fraunhofer, Joseph von (1821). "Neue Modifikation des Lichtes durch gegenseitige Einwirkung und Beugung der Strahlen, und Gesetze derselben" [New modification of light by the mutual influence and the diffraction of [light] rays, and the laws thereof]. Denkschriften der Königlichen Akademie der Wissenschaften zu München (Memoirs of the Royal Academy of Science in Munich). 8: 3–76.
  12. ^ Fraunhofer, Joseph von (1823). "Kurzer Bericht von den Resultaten neuerer Versuche über die Gesetze des Lichtes, und die Theorie derselben" [Short account of the results of new experiments on the laws of light, and the theory thereof]. Annalen der Physik. 74 (8): 337–378. Bibcode:1823AnP....74..337F. doi:10.1002/andp.18230740802.
  13. ^ Thomas Young (1 January 1804). "The Bakerian Lecture: Experiments and calculations relative to physical optics". Philosophical Transactions of the Royal Society of London. 94: 1–16. Bibcode:1804RSPT...94....1Y. doi:10.1098/rstl.1804.0001. S2CID 110408369.. (Note: This lecture was presented before the Royal Society on 24 November 1803.)
  14. ^ Fresnel, Augustin-Jean (1816), "Mémoire sur la diffraction de la lumière" ("Memoir on the diffraction of light"), Annales de Chimie et de Physique, vol. 1, pp. 239–81 (March 1816); reprinted as "Deuxième Mémoire…" ("Second Memoir…") in Oeuvres complètes d'Augustin Fresnel, vol. 1 (Paris: Imprimerie Impériale, 1866), pp. 89–122. (Revision of the "First Memoir" submitted on 15 October 1815.)
  15. ^ Fresnel, Augustin-Jean (1818), "Mémoire sur la diffraction de la lumière" ("Memoir on the diffraction of light"), deposited 29 July 1818, "crowned" 15 March 1819, published in Mémoires de l'Académie Royale des Sciences de l'Institut de France, vol. V (for 1821 & 1822, printed 1826), pp. 339–475; reprinted in Oeuvres complètes d'Augustin Fresnel, vol. 1 (Paris: Imprimerie Impériale, 1866), pp. 247–364; partly translated as "Fresnel's prize memoir on the diffraction of light", in H. Crew (ed.), The Wave Theory of Light: Memoirs by Huygens, Young and Fresnel, American Book Company, 1900, pp. 81–144. (First published, as extracts only, in Annales de Chimie et de Physique, vol. 11 (1819), pp. 246–96, 337–78.)
  16. ^ Turner, G. L'E. (1967). "The contributions to Science of Friedrich Adolph Nobert". Bulletin of the Institute of Physics and the Physical Society. 18 (10): 338–348. doi:10.1088/0031-9112/18/10/006.
  17. ^ Warner, Deborah J. (1971). "Lewis M. Rutherfurd: Pioneer Astronomical Photographer and Spectroscopist". Technology and Culture. 12 (2): 190–216. doi:10.2307/3102525. JSTOR 3102525. S2CID 112109352.
  18. ^ Warner, Deborah J. (1988). The Michelson Era in American Science 1870-1930. New York: American Institute of Physics. pp. 2–12.
  19. ^ Hentschel, Klaus (1993). "The Discovery of the Redshift of Solar Fraunhofer Lines by Rowland and Jewell in Baltimore around 1890" (PDF). Historical Studies in the Physical and Biological Sciences. 23 (2): 219–277. doi:10.2307/27757699. JSTOR 27757699. Archived (PDF) from the original on 9 October 2022.
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