Image sensor
An image sensor or imager is a
The two main types of electronic image sensors are the
CCD vs. CMOS sensors
The two main types of
Cameras integrated in small consumer products generally use CMOS sensors, which are usually cheaper and have lower power consumption in battery powered devices than CCDs.[8] CCD sensors are used for high end broadcast quality video cameras, and CMOS sensors dominate in still photography and consumer goods where overall cost is a major concern. Both types of sensor accomplish the same task of capturing light and converting it into electrical signals.
Each cell of a
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.[9] Some CMOS imaging sensors also use Back-side illumination to increase the number of photons that hit the photodiode.[10] CMOS sensors can potentially be implemented with fewer components, use less power, and/or provide faster readout than CCD sensors.[11] 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 arrays and has been adapted to silicon-based detector technology.[12] 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.[13]
Performance
There are many parameters that can be used to evaluate the performance of an image sensor, including dynamic range, signal-to-noise ratio, and low-light sensitivity. For sensors of comparable types, the signal-to-noise ratio and dynamic range improve as the size increases. It is because in a given integration (exposure) time, more photons hit the pixel with larger area.
Exposure-time control
Color separation
There are several main types of color image sensors, differing by the type of color-separation mechanism:
- Integral color sensorsBayer pattern, uses a checkerboard arrangement of two green pixels for each red and blue pixel, although many other color filter patterns have been developed, including patterns using cyan, magenta, yellow, and white pixels.[16] Integral color sensors were initially manufactured by transferring colored dyes through photoresist windows onto a polymer receiving layer coated on top of a monochrome CCD sensor.[17] Since each pixel provides only a single color (such as green), the "missing" color values (such as red and blue) for the pixel are interpolated using neighboring pixels.[18] This processing is also referred to as demosaicingor de-bayering.
- Foveon X3 sensor, using an array of layered pixel sensors, separating light via the inherent wavelength-dependent absorption property of silicon, such that every location senses all three color channels. This method is similar to how color film for photography works.
- television broadcasting, video editing and chroma keyvisual effects.
Specialty sensors
Special sensors are used in various applications such as
While in general, digital cameras use a flat sensor, Sony prototyped a curved sensor in 2014 to reduce/eliminate Petzval field curvature that occurs with a flat sensor. Use of a curved sensor allows a shorter and smaller diameter of the lens with reduced elements and components with greater aperture and reduced light fall-off at the edge of the photo.[21]
History
Early analog sensors for visible light were
The basis for modern solid-state image sensors is MOS technology,[23][24] which originates from the invention of the MOSFET by Mohamed M. Atalla and Dawon Kahng at Bell Labs in 1959.[25] Later research on MOS technology led to the development of solid-state semiconductor image sensors, including the charge-coupled device (CCD) and later the active-pixel sensor (CMOS sensor).[23][24]
The
In June 2022, Samsung Electronics announced that it had created a 200 million pixel image sensor. The 200MP ISOCELL HP3 has 0.56 micrometer pixels with Samsung reporting that previous sensors had 0.64 micrometer pixels, a 12% decrease since 2019. The new sensor contains 200 million pixels in a 1-by-1.4-inch (25 by 36 mm) lens.[28]
Charge-coupled device
The
Early CCD sensors suffered from
Active-pixel sensor
The
Other image sensors
The first commercial
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 5 μm NMOS integrated circuit sensor chip.[2][1] Since the first commercial optical mouse, the IntelliMouse introduced in 1999, most optical mouse devices use CMOS sensors.[36]
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.[37]
See also
- List of sensors used in digital cameras
- Contact image sensor (CIS)
- Electro-optical sensor
- Video camera tube, used before image sensors for video
- Semiconductor detector
- Fill factor
- Full-frame digital SLR
- Image resolution
- Image sensor format, the sizes and shapes of common image sensors
- Color filter array, mosaic of tiny color filters over color image sensors
- Sensitometry, the scientific study of light-sensitive materials
- History of television, the development of electronic imaging technology since the 1880s
- List of large sensor interchangeable-lens video cameras
- Oversampled binary image sensor
- Computer vision
- Push broom scanner
- Whisk broom scanner
References
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- ^ Brain, Marshall; Carmack, Carmen (24 April 2000). "How Computer Mice Work". HowStuffWorks. Retrieved 9 October 2019.
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- ISBN 9780470537947. Retrieved 6 October 2019.
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- ^ .
- ^ "CMOS Is Winning the Camera Sensor Battle, and Here's Why". techhive.com. 2011-12-29. Archived from the original on 2017-05-01. Retrieved 2017-04-27.
- ^ a b "CCD and CMOS sensors". Canon Professional Network. Archived from the original on 28 April 2018. Retrieved 28 April 2018.
- ^ "What is a backlit CMOS sensor?". techradar.com. 2012-07-02. Archived from the original on 2017-05-06. Retrieved 2017-04-27.
- ^ Moynihan, Tom (29 December 2011). "CMOS Is Winning the Camera Sensor Battle, and Here's Why". Archived from the original on 25 September 2015. Retrieved 10 April 2015.
- ^ scmos.com Archived 2012-06-03 at the Wayback Machine, home page
- ^ ieee.org - CCD in CMOS Archived 2015-06-22 at the Wayback Machine Padmakumar R. Rao et al., "CCD structures implemented in standard 0.18 μm CMOS technology"
- ISBN 9781420026856.
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- ^ "Deepest Ever Look into Orion". Archived from the original on 13 July 2016. Retrieved 13 July 2016.
- ISBN 979-8698999171.
- ^ Dent, Steve (8 July 2014). "Sony's first 'curved sensor' photo may herald better images, cheaper lenses". Archived from the original on July 11, 2014. Retrieved July 8, 2014.
- ISBN 9781136778445.
- ^ ISBN 9783319490885.
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- ^ "1960: Metal Oxide Semiconductor (MOS) Transistor Demonstrated". The Silicon Engine. Computer History Museum. Retrieved August 31, 2019.
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- ^ Daily Consular and Trade Reports. Department of Commerce and Labor, Bureau of Manufactures. 1914.
- ^ Web, Desk (2022-06-25). "Samsung Electronics releases a sensor with 200 million pixels". BOL News. Retrieved 2022-06-25.
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- ^ U.S. Patent 4,484,210: Solid-state imaging device having a reduced image lag
- S2CID 18831792. Archived from the original(PDF) on 9 March 2019. Retrieved 8 October 2019.
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- ^ "CMOS Image Sensor Sales Stay on Record-Breaking Pace". IC Insights. May 8, 2018. Retrieved 6 October 2019.
- ^ Benchoff, Brian (17 April 2016). "Building the First Digital Camera". Hackaday. Retrieved 30 April 2016.
the Cyclops was the first digital camera
- ^ Brain, Marshall; Carmack, Carmen (24 April 2000). "How Computer Mice Work". HowStuffWorks. Retrieved 9 October 2019.
- ^ "Super Sensitive Sensor Sees What You Can't". npr.org. Archived from the original on 24 March 2018. Retrieved 28 April 2018.
External links
- Digital Camera Sensor Performance Summary by Roger Clark
- Clark, Roger. "Does Pixel Size Matter?". clarkvision.com. (with graphical buckets and rainwater analogies)