Image sensor: Difference between revisions

Revision as of 07:41, 1 May 2024

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A CMOS image sensor has an amplifier for each pixel compared to the few amplifiers of a CCD. This results in less area for the capture of photons than a CCD, but this problem has been overcome by using microlenses in front of each photodiode, which focus light into the photodiode that would have otherwise hit the amplifier and not been detected.<ref name="auto"/> Some CMOS imaging sensors also use [[back-illuminated sensor|Back-side illumination]] to increase the number of photons that hit the photodiode.<ref>{{cite web |url=http://www.techradar.com/news/photography-video-capture/cameras/what-is-a-backlit-cmos-sensor-1086234 |title=What is a backlit CMOS sensor? |website=techradar.com |date=2012-07-02 |access-date=2017-04-27 |url-status=live |archive-url=https://web.archive.org/web/20170506184555/http://www.techradar.com/news/photography-video-capture/cameras/what-is-a-backlit-cmos-sensor-1086234 |archive-date=2017-05-06 }}</ref> CMOS sensors can potentially be implemented with fewer components, use less power, and/or provide faster readout than CCD sensors.<ref>{{cite web|last1=Moynihan|first1=Tom|title=CMOS Is Winning the Camera Sensor Battle, and Here's Why|date=29 December 2011|url=http://www.techhive.com/article/246931/cmos_is_winning_the_camera_sensor_battle_and_heres_why.html?page=0|access-date=10 April 2015|url-status=live|archive-url=https://web.archive.org/web/20150925220239/http://www.techhive.com/article/246931/cmos_is_winning_the_camera_sensor_battle_and_heres_why.html?page=0|archive-date=25 September 2015}}</ref> They are also less vulnerable to static electricity discharges.

Another design, a hybrid CCD/CMOS architecture (sold under the name "[[sCMOS]]") consists of CMOS readout integrated circuits (ROICs) that are bump bonded to a CCD imaging substrate – a technology that was developed for infrared [[staring array]]s and has been adapted to silicon-based detector technology.<ref name="test3">[http://www.scmos.com/ scmos.com] {{webarchive|url=https://web.archive.org/web/20120603082322/http://www.scmos.com/ |date=2012-06-03 }}, home page</ref> Another approach is to utilize the very fine dimensions available in modern CMOS technology to implement a CCD like structure entirely in CMOS technology: such structures can be achieved by separating individual poly-silicon gates by a very small gap; though still a product of research hybrid sensors can potentially harness the benefits of both CCD and CMOS imagers.<ref name="test4">[http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=4489895 ieee.org - CCD in CMOS] {{webarchive|url=https://web.archive.org/web/20150622073305/http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=4489895 |date=2015-06-22 }} Padmakumar R. Rao et al., "CCD structures implemented in standard 0.18 µmμm CMOS technology"</ref>

==Performance==

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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 µmμm process|5{{nbsp}}µmμm]] [[NMOS logic|NMOS]] [[integrated circuit]] sensor chip.<ref name="Springer"/><ref name="VLSI Systems and Computations"/> 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>