Image sensor: Difference between revisions

Revision as of 14:49, 4 January 2025

Revision as of 14:50, 4 January 2025

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{{Short description|Device that converts images into electronic signals}}An '''image sensor''' or '''imager''' is a sensor that detects and conveys information used to form an image. It does so by converting the variable [[attenuation]] of light [[wave]]s (as they [[refraction|pass through]] or [[reflection (physics)|reflect off]] objects) into [[signal (electrical engineering)|signals]], small bursts of [[electric current|current]] that convey the information. The waves can be light or other [[electromagnetic radiation]]. Image sensors are used in [[electronics|electronic]] imaging devices of both [[analogue electronics|analog]] and [[digital electronics|digital]] types, which include [[digital camera]]s, [[camera module]]s, [[camera phones]], [[optical mouse]] devices,<ref name="VLSI Systems and Computations">{{cite book | chapter = The Optical Mouse, and an Architectural Methodology for Smart Digital Sensors | title = VLSI Systems and Computations | pages = 1–19 | last1=Lyon | first1=Richard F. | author1-link=Richard F. Lyon |editor1=H. T. Kung |editor2=Robert F. Sproull |editor3=Guy L. Steele | publisher=Computer Science Press |date=August 1981 | doi=10.1007/978-3-642-68402-9_1 | chapter-url=http://bitsavers.trailing-edge.com/pdf/xerox/parc/techReports/VLSI-81-1_The_Optical_Mouse.pdf| isbn = 978-3-642-68404-3 | s2cid = 60722329 }}</ref><ref name="Springer">{{cite book |last1=Lyon |first1=Richard F. |author1-link=Richard F. Lyon |chapter=The Optical Mouse: Early Biomimetic Embedded Vision |title=Advances in Embedded Computer Vision |date=2014 |publisher=Springer |isbn=9783319093871 |pages=3–22 (3) |chapter-url=https://books.google.com/books?id=p_GbBQAAQBAJ&pg=PA3}}</ref><ref>{{cite web |last1=Brain |first1=Marshall |last2=Carmack |first2=Carmen |title=How Computer Mice Work |url=https://computer.howstuffworks.com/mouse4.htm |website=[[HowStuffWorks]] |access-date=9 October 2019 |date=24 April 2000}}</ref> [[medical imaging]] equipment, [[night vision]] equipment such as [[thermography|thermal imaging]] devices, [[radar]], [[sonar]], and others. As [[technological change|technology changes]], electronic and [[digital imaging]] tends to replace chemical and analog imaging.

The two main types of electronic image sensors are the [[charge-coupled device]] (CCD) and the [[active-pixel sensor]] ([[CMOS]] sensor). Both CCD and CMOS sensors are based on [[metal–oxide–semiconductor]] (MOS) technology, with CCDs based on [[MOS capacitor]]s and CMOS sensors based on [[MOSFET]] (MOS field-effect transistor) [[amplifiers]]. Analog sensors for invisible radiation tend to involve [[vacuum tube]]s of various kinds, while digital sensors include [[flat-panel detector]]s.

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The first commercial [[digital camera]], the [[Cromemco Cyclops]] in 1975, used a 32×32 MOS image sensor. It was a modified MOS dynamic [[Random-access memory|RAM]] ([[Dynamic random-access memory|DRAM]]) [[memory chip]].<ref name="hackaday">{{cite web |last1=Benchoff|first1=Brian|title=Building the First Digital Camera|url=http://hackaday.com/2016/04/17/building-the-first-digital-camera/|website=[[Hackaday]]|access-date=30 April 2016|date=17 April 2016|quote=the Cyclops was the first digital camera}}</ref>

MOS image sensors are widely used in [[optical mouse]] technology. The first optical mouse, invented by [[Richard F. Lyon]] at [[Xerox]] in 1980, used a [[6 μm process|5{{nbsp}}μm]] [[NMOS logic|NMOS]] [[integrated circuit]] sensor chip.<ref name="Springer">{{cite book |last1=Lyon |first1=Richard F. |author1-link=Richard F. Lyon |title=Advances in Embedded Computer Vision |date=2014 |publisher=Springer |isbn=9783319093871 |pages=3–22 (3) |chapter=The Optical Mouse: Early Biomimetic Embedded Vision |chapter-url=https://books.google.com/books?id=p_GbBQAAQBAJ&pg=PA3}}</ref><ref name="VLSI Systems and Computations">{{cite book |last1=Lyon |first1=Richard F. |author1-link=Richard F. Lyon |title=VLSI Systems and Computations |date=August 1981 |publisher=Computer Science Press |isbn=978-3-642-68404-3 |editor1=H. T. Kung |pages=1–19 |chapter=The Optical Mouse, and an Architectural Methodology for Smart Digital Sensors |doi=10.1007/978-3-642-68402-9_1 |editor2=Robert F. Sproull |editor3=Guy L. Steele |chapter-url=http://bitsavers.trailing-edge.com/pdf/xerox/parc/techReports/VLSI-81-1_The_Optical_Mouse.pdf |s2cid=60722329}}</ref> Since the first commercial optical mouse, the [[IntelliMouse]] introduced in 1999, most optical mouse devices use CMOS sensors.<ref>{{cite web |last1=Brain |first1=Marshall |last2=Carmack |first2=Carmen |title=How Computer Mice Work |url=https://computer.howstuffworks.com/mouse4.htm |website=[[HowStuffWorks]] |access-date=9 October 2019 |language=en |date=24 April 2000}}</ref>

In February 2018, researchers at [[Dartmouth College]] announced a new image sensing technology that the researchers call QIS, for Quanta Image Sensor. Instead of pixels, QIS chips have what the researchers call "jots." Each jot can detect a single particle of light, called a [[photon]].<ref>{{cite news|url=https://www.npr.org/sections/alltechconsidered/2018/02/13/585149644/super-sensitive-sensor-sees-what-you-cant|title=Super Sensitive Sensor Sees What You Can't|website=npr.org|access-date=28 April 2018|url-status=live|archive-url=https://web.archive.org/web/20180324010947/https://www.npr.org/sections/alltechconsidered/2018/02/13/585149644/super-sensitive-sensor-sees-what-you-cant|archive-date=24 March 2018}}</ref>