{{short description|Instrument for measuring variation in light pulse intensity over time}} [[File:Working principle of a streak camera.png|thumb|upright=1.2|Working principle of a streak camera]]
A '''streak camera''' is an instrument for measuring the variation in a pulse of [[light]]'s [[intensity (physics)|intensity]] with time. They are used to measure the pulse duration of some [[ultrafast laser]] systems and for applications such as [[time-resolved spectroscopy]] and [[LIDAR]].
==Mechanical types== Mechanical streak cameras use a rotating [[mirror]] or moving slit system to deflect the light beam. They are limited in their maximum scan speed and thus temporal resolution.<ref>{{cite book|last1=Horn|first1=Alexander|title=Ultra-fast Material Metrology|date=2009|publisher=John Wiley & Sons|isbn=9783527627936|page=7|url=https://books.google.com/books?id=IdCg2dDZQr8C&pg=PA7|language=en}}</ref>
==Optoelectronic type== [[optoelectronics|Optoelectronic]] streak cameras work by directing the light onto a [[photocathode]], which when hit by photons produces [[electron]]s via the [[photoelectric effect]]. The electrons are accelerated in a [[cathode-ray tube]] and pass through an [[electric field]] produced by a pair of plates, which deflects the electrons sideways. By modulating the [[electric potential]] between the plates, the electric field is quickly changed to give a time-varying deflection of the electrons, sweeping the electrons across a [[phosphor]] screen at the end of the tube.<ref>{{cite book|last1=Mourou|first1=Gerard A.|last2=Bloom|first2=David M.|last3=Lee|first3=Chi-H.|title=Picosecond Electronics and Optoelectronics: Proceedings of the Topical Meeting Lake Tahoe, Nevada, March 13–15, 1985|date=2013|publisher=Springer Science & Business Media|isbn=9783642707803|page=58|url=https://books.google.com/books?id=Vl7rCAAAQBAJ&pg=PA58|language=en}}</ref> A linear detector, such as a [[charge-coupled device]] (CCD) array is used to measure the streak pattern on the screen, and thus the temporal profile of the light pulse.<ref> {{cite web | title = Guide to streak cameras | url = http://www.hamamatsu.com/resources/pdf/sys/SHSS0006E_STREAK.pdf | accessdate = 2015-07-07 }} </ref>
The time-resolution of the best optoelectronic streak cameras is around 180 [[femtosecond]]s.<ref> Akira Takahashi et al.: "New femtosecond streak camera with temporal resolution of 180 fs" Proc. SPIE 2116, Generation, Amplification, and Measurement of Ultrashort Laser Pulses, 275 (May 16, 1994); {{doi|10.1117/12.175863}} </ref> Measurement of pulses shorter than this duration requires other techniques such as [[optical autocorrelation]] and [[frequency-resolved optical gating]] (FROG).<ref>{{cite book|last1=Chang|first1=Zenghu|title=Fundamentals of Attosecond Optics|date=2016|publisher=CRC Press|isbn=9781420089387|page=84|url=https://books.google.com/books?id=J5HLBQAAQBAJ&pg=PA84|language=en}}</ref>
In December 2011, a team at [[Massachusetts Institute of Technology|MIT]] released images combining the use of a streak camera with repeated laser pulses to simulate a [[Film|movie]] with a [[frame rate]] of one [[Orders of magnitude (numbers)#1012|trillion]] frames per second.<ref> {{cite web | title = MIT's trillion frames per second light-tracking camera | url = https://www.bbc.co.uk/news/technology-16163931 | publisher = BBC News | date = 2011-12-13 | accessdate = 2011-12-14 }} </ref> This was surpassed in 2020 by a team from [[Caltech]] that achieved frame rates of 70 trillion fps.<ref>{{cite journal |last1=Wang |first1=Peng |last2=Liang |first2=Jinyang |last3=Wang |first3=Lihong V. |title=Single-shot ultrafast imaging attaining 70 trillion frames per second |journal=Nature Communications |date=29 April 2020 |volume=11 |issue=1 |page=2091 |doi=10.1038/s41467-020-15745-4|pmid=32350256 |pmc=7190645 |bibcode=2020NatCo..11.2091W |doi-access=free }}</ref>
==See also== * [[Photo finish]], which uses a much slower but 2-dimensional version of a camera mapping time into a spatial dimension * [[Femto-photography]]
==References==
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[[Category:Optical metrology]]
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