Editing Charge-coupled device (section)

== Use in astronomy ==
[[Image:SDSSFaceplate.gif|thumb|right|Array of 30 CCDs used on the [[Sloan Digital Sky Survey]] telescope imaging camera, an example of "drift-scanning".]]Due to the high quantum efficiencies of charge-coupled device (CCD) (the ideal [[quantum efficiency]] is 100%, one generated electron per incident photon), linearity of their outputs, ease of use compared to photographic plates, and a variety of other reasons, CCDs were very rapidly adopted by astronomers for nearly all UV-to-infrared applications.

Thermal noise and [[cosmic ray]]s may alter the pixels in the CCD array. To counter such effects, astronomers take several exposures with the CCD shutter closed and opened. The average of images taken with the shutter closed is necessary to lower the random noise. Once developed, the [[dark frame subtraction|dark frame average image is then subtracted]] from the open-shutter image to remove the dark current and other systematic defects ([[dead pixel]]s, hot pixels, etc.) in the CCD. Newer Skipper CCDs counter noise by collecting data with the same collected charge multiple times and has applications in precision light [[Dark matter|Dark Matter]] searches and [[neutrino]] measurements.<ref>{{Cite journal|last1=Aguilar-Arevalo|first1=A.|last2=Amidei|first2=D.|last3=Baxter|first3=D.|last4=Cancelo|first4=G.|last5=Vergara|first5=B. A. Cervantes|last6=Chavarria|first6=A. E.|last7=Darragh-Ford|first7=E.|last8=Neto|first8=J. R. T. de Mello|last9=D'Olivo|first9=J. C.|last10=Estrada|first10=J.|last11=Gaïor|first11=R.|date=2019-10-31|title=Constraints on Light Dark Matter Particles Interacting with Electrons from DAMIC at SNOLAB|journal=Physical Review Letters|volume=123|issue=18|pages=181802|doi=10.1103/PhysRevLett.123.181802|pmid=31763884|issn=0031-9007|arxiv=1907.12628|bibcode=2019PhRvL.123r1802A|s2cid=198985735}}</ref><ref>{{cite web | last = Abramoff | first = Orr | title = Skipper CCD | website = SENSEI | url = https://sensei-skipper.github.io/#SkipperCCD | access-date = 11 April 2021}}</ref><ref>{{Cite journal|last1=Aguilar-Arevalo|first1=Alexis|last2=Bertou|first2=Xavier|last3=Bonifazi|first3=Carla|last4=Cancelo|first4=Gustavo|last5=Castañeda|first5=Alejandro|last6=Vergara|first6=Brenda Cervantes|last7=Chavez|first7=Claudio|last8=D'Olivo|first8=Juan C.|last9=Anjos|first9=João C. dos|last10=Estrada|first10=Juan|last11=Neto|first11=Aldo R. Fernandes|date=2019-11-13|title=Exploring low-energy neutrino physics with the Coherent Neutrino Nucleus Interaction Experiment (CONNIE)|journal=Physical Review D|volume=100|issue=9|pages=092005|doi=10.1103/PhysRevD.100.092005|arxiv=1906.02200|issn=2470-0010|hdl=11336/123886|s2cid=174802422|hdl-access=free}}</ref>

The [[Hubble Space Telescope]], in particular, has a highly developed series of steps ("data reduction pipeline") to convert the raw CCD data to useful images.<ref name="ESO-Hainaut-CCD image processing">
{{Cite web| url = http://www.eso.org/~ohainaut/ccd | title = Basic CCD image processing |date = December 2006| last = Hainaut | first = Oliver R. | access-date = January 15, 2011 }}<br>
{{Cite web| url = http://www.eso.org/~ohainaut/ccd/sn.html | title = Signal, Noise and Detection | date = June 1, 2005 | last = Hainaut | first = Oliver R. | access-date = October 7, 2009 }}<br>
{{Cite web| url = http://www.eso.org/~ohainaut/images/imageProc.html | title = Retouching of astronomical data for the production of outreach images | date = May 20, 2009 | last = Hainaut | first = Oliver R. | access-date = October 7, 2009 }} <br>(Hainaut is an astronomer at the [http://www.eso.org/~ohainaut/cv.html European Southern Observatory]) <br>
</ref>

CCD cameras used in [[astrophotography]] often require sturdy mounts to cope with vibrations from wind and other sources, along with the tremendous weight of most imaging platforms. To take long exposures of galaxies and nebulae, many astronomers use a technique known as [[autoguider|auto-guiding]]. Most autoguiders use a second CCD chip to monitor deviations during imaging. This chip can rapidly detect errors in tracking and command the mount motors to correct for them.

An unusual astronomical application of CCDs, called drift-scanning, uses a CCD to make a fixed telescope behave like a tracking telescope and follow the motion of the sky. The charges in the CCD are transferred and read in a direction parallel to the motion of the sky, and at the same speed. In this way, the telescope can image a larger region of the sky than its normal field of view. The [[Sloan Digital Sky Survey]] is the most famous example of this, using the technique to produce a survey of over a quarter of the sky. The [[Gaia space telescope]] is another instrument operating in this mode, rotating about its axis at a constant rate of 1 revolution in 6 hours and scanning a 360° by 0.5° strip on the sky during this time; a star traverses the entire focal plane in about 40 seconds (effective exposure time).

In addition to imagers, CCDs are also used in an array of analytical instrumentation  including [[spectrometer]]s<ref>{{cite journal |first1=V. |last1=Deckert |first2=W. |last2=Kiefer |title=Scanning multichannel technique for improved spectrochemical measurements with a CCD camera and its application to Raman spectroscopy |journal=Appl. Spectrosc. |volume=46 |issue= 2|pages=322–328 |year=1992 |doi=10.1366/0003702924125500 |bibcode=1992ApSpe..46..322D |s2cid=95441651 }}</ref> and [[List of types of interferometers|interferometers]].<ref>{{cite journal |first=F. J. |last=Duarte |author-link=F. J. Duarte |title=On a generalized interference equation and interferometric measurements |journal=Opt. Commun. |volume=103 |issue=1–2 |pages=8–14 |year=1993 |doi=10.1016/0030-4018(93)90634-H |bibcode=1993OptCo.103....8D }}</ref>