Editing Laser (section)

{{Short description|Device which emits light via optical amplification}}
{{other uses}}
{{redirect-distinguish|Laser beam|LazarBeam|Lazer Beam}}
{{pp-semi-indef}}
{{Use mdy dates|date=June 2012}}
{{Use American English|date=September 2016}}
[[File:Guiding the Milky Way (potw2222a).jpg|thumb|upright=1.5|A telescope in the [[Very Large Telescope]] system producing four orange [[laser guide star]]s |alt=A telescope emitting four orange laser beams]]

A '''laser''' is a device that emits [[light]] through a process of [[optical amplification]] based on the [[stimulated emission]] of [[electromagnetic radiation]]. The word ''laser'' originated as an [[acronym]] for '''light amplification by stimulated emission of radiation'''.<ref>{{Cite book |last=Taylor |first=Nick |title=Laser: The Inventor, The Nobel Laureate, and The Thirty-Year Patent War |publisher=[[Simon & Schuster]] |year=2000 |isbn=978-0684835150 |page=[https://books.google.com/books?id=Q7DaoWJyPjIC&pg=PA66 66]}}</ref><ref>{{Cite book |last1=Ross T. |first1=Adam |url=https://books.google.com/books?id=z1BRAAAAMAAJ |title=Proceedings of Laser Surgery: Advanced Characterization, Therapeutics, and Systems |last2=Becker G. |first2=Daniel |date=2001 |publisher=[[SPIE]] |isbn=978-0-8194-3922-2 |pages=396 |language=en}}</ref> The first laser was built in 1960 by [[Theodore Maiman]] at [[Hughes Research Laboratories]], based on theoretical work by [[Charles H. Townes]] and [[Arthur Leonard Schawlow]] and the optical amplifier patented by [[Gordon Gould]].<ref name="pmid36063315">{{cite book |vauthors=Taylor N |title=Optical Tweezers |chapter=The Invention of the Laser |series=Methods Mol Biol |volume=2478 |pages=3–10 |date=2022 |pmid=36063315 |doi=10.1007/978-1-0716-2229-2_1 |isbn=978-1-0716-2228-5 |chapter-url=https://pubmed.ncbi.nlm.nih.gov/36063315/}}</ref><ref>{{cite web | title=Gordon Gould | website=The Independent | date=2005-09-23 | url=https://www.independent.co.uk/news/obituaries/gordon-gould-508147.html | access-date=2025-01-10}}</ref><ref>{{Cite web |title=December 1958: Invention of the Laser |url=http://www.aps.org/publications/apsnews/200312/history.cfm|access-date=January 27, 2022 |website=aps.org |language=en|archive-date=December 10, 2021 |archive-url=https://web.archive.org/web/20211210153614/https://www.aps.org/publications/apsnews/200312/history.cfm |url-status=live}}</ref>

A laser differs from other sources of light in that it emits light that is [[coherence (physics)|''coherent'']]. [[Spatial coherence]] allows a laser to be focused to a tight spot, enabling uses such as optical communication,<ref>{{cite journal |last1=Ning |first1=Jinna |last2=Zhang |first2=Wenrui |last3=Cao |first3=Changqing |last4=Feng |first4=Zhejun |last5=Zeng |first5=Xiaodong |last6=Wang |first6=Ting |last7=Wang |first7=Rui |last8=Song |first8=Qi |last9=Fan |first9=Shuanglin |title=Collimation of laser diode beams for free space optical communications |journal=Infrared Physics & Technology |publisher=Elsevier BV |volume=102 |year=2019 |issn=1350-4495 |doi=10.1016/j.infrared.2019.102996 |page=102996 |bibcode=2019InPhT.10202996N |url=https://www.researchgate.net/publication/334906586}}</ref> [[laser cutting]], and [[Photolithography#Light sources|lithography]]. It also allows a laser beam to stay narrow over great distances ([[collimated light|collimation]]), used in [[laser pointer]]s, [[lidar]], and [[free-space optical communication]]. Lasers can also have high [[temporal coherence]], which permits them to emit light with a very narrow [[frequency spectrum]]. Temporal coherence can also be used to produce [[ultrashort pulse]]s of light with a broad spectrum but durations measured in [[attosecond]]s.<ref>{{cite journal |url=https://www.nature.com/articles/d41586-023-03047-w |journal=Nature |date=October 3, 2023 |title=Physicists who built ultrafast 'attosecond' lasers win Nobel Prize |first1=Davide |last1=Castelvecchi |first2=Katharine |last2=Sanderson |volume=622 |issue=7982 |pages=225–227 |doi=10.1038/d41586-023-03047-w |pmid=37789199 |bibcode=2023Natur.622..225C |access-date=November 14, 2024}}</ref>

Lasers are used in [[fiber-optic communication|fiber-optic]] and free-space optical communications, [[optical disc drive]]s, [[laser printer]]s, [[barcode scanner]]s, semiconductor chip manufacturing ([[photolithography]], [[etching]]), [[laser surgery]] and skin treatments, cutting and [[laser welding|welding]] materials, military and [[law enforcement]] devices for marking targets and [[Laser rangefinder|measuring range]] and speed, and in [[laser lighting display]]s for entertainment. The laser is regarded as one of the greatest inventions of the 20th century.<ref>{{Cite journal |last=Trainer |first=Matthew |date=2010 |title=The 50th anniversary of the laser |url=https://linkinghub.elsevier.com/retrieve/pii/S0172219010000529 |journal=World Patent Information |language=en |volume=32 |issue=4 |pages=326–330 |doi=10.1016/j.wpi.2010.06.005|bibcode=2010WPatI..32..326T }}</ref><ref>{{Citation |last=Saleh |first=Bahaa |title=The Laser |date=2016 |work=Optics in Our Time |pages=71–85 |editor-last=Al-Amri |editor-first=Mohammad D. |url=http://link.springer.com/10.1007/978-3-319-31903-2_4 |access-date= |place=Cham |publisher=Springer International Publishing |language=en |doi=10.1007/978-3-319-31903-2_4 |bibcode=2016oot..book...71S |isbn=978-3-319-31902-5 |editor2-last=El-Gomati |editor2-first=Mohamed |editor3-last=Zubairy |editor3-first=M. Suhail}}</ref>