CCD

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CCD

Abbrev. for charge-coupled device. A light-sensitive electronic detector, invented 1970, now widely used in ground- and space-based astronomy for imaging, photometry, spectroscopy, astrometry, etc. CCDs are normally sensitive over a wide range of wavelengths from blue light to near-infrared; developments have extended the range further into the IR (see infrared detectors), and into the ultraviolet and X-ray regions (to energies up to about 6 keV). A CCD is small (typically several square centimeters) compared with a photographic plate, and therefore covers a relatively small field of view. It also has a lower resolution than a fine-grained photographic emulsion. It does, however, have a much higher quantum efficiency – i.e. is a much more efficient detector – than emulsion; exposure times are therefore relatively much shorter. CCDs are thus well suited to the imaging of faint objects. They also have a linear response over a wide range of illumination, and in a properly designed and operating CCD system, the response is very stable over long timescales.

Astronomical CCDs are fabricated as a two-dimensional array of tiny pixels (picture elements) on a thin wafer of semiconductor, usually silicon; there may be up to several thousand rows and columns of pixels. When light or other radiation is directed onto this array, each pixel responds to the photons falling on it by producing electrons. Electric charge thus accumulates in each pixel in proportion to the amount of incident radiation. After an exposure, these packets of charge are shifted out of the array and the accumulated charge in each pixel is measured, row by row. The values are digitized and stored in a computer, and may be used to form an image on a computer screen or may be further manipulated or analyzed. There is a direct relationship between the intensity of the recorded image and the original exposure, hence the linear response. Noise is, however, introduced as the charges are moved out of the CCD, amplified, digitized, and stored in the computer, thus placing a lower limit on the signal that can be accurately recorded; this readout noise can be reduced by cooling the CCD.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006

CCD

(electronics)
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

CCD

This article is provided by FOLDOC - Free Online Dictionary of Computing (foldoc.org)

CCD

(1) (Charge-Coupled Device) See CCD sensor.

(2) (Consumer Computing Device) An earlier term for a low-cost consumer-oriented computing product such as a PDA or Internet appliance.
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References in periodicals archive ?
Most of the experimentation was done at lower frequencies (around 10 MHz), which allowed wafer probing of the CCDs. High frequency testing requires individual device packaging.
Invented in 1969 at AT&T's Bell Labs, CCD technology relies on the collection of photons from a photoactive layer, typically an epitaxially-deposited layer of doped silicon.
Sanyo Electric, one of the world's largest digital still camera manufacturers, began making CCDs in the early 1980s.
Because there were several activities to choose from for each grade level of the KGP, we selected four weekly activities from the curriculum that were believed to be most representative of the concepts measured on the four CCDS subscales selected for analysis in the present study.
An offset CCD detector provides close access to samples for small-angle x-ray scattering (SAXS) and low-grazing-incidence applications.
Nic Beishon, head of commercial at Equifax, said, 'CCDS is a game changer for many businesses who have the financial ability to repay a loan but who are currently either denied it or left in limbo when a lack of information leaves banks unable to make a timely decision.
Organisee par le ministere de la Culture et le Centre culturel et de documentation saharienne (CCDS), l'exposition regroupe plusieurs series de photographies prisent entre le mois de fevrier et le mois de juillet 1903 dans le sud algerien par deux peres blancs : Mgr Guerin et le pere Vellard, en plus de photographies d'Alger et de Kabylie, datant de la meme epoque.
The company says like its predecessors in the same line, this new Pregius series sensor employs global-shutter technology and users of previous-generation VC Z series cameras are very familiar with it and have come to appreciate its hands-on benefits over rolling shutters or CCDs: there is no bloom, smear, distortion, or overexposure in images captured with global shutter CMOS sensors.
HYDERABAD -- The Centre for Coastal and Deltaic Studies (CCDS), Sindh University Campus Thatta in collaboration with Sindh Livestock and Fisheries Department organized daylong national seminar titled Education and Research on Coastal Fisheries Management to mark World Fisheries Day.
Joel Doria, Cebu City police director, said they could not conclude that the 'CCDS' written on a piece of carton left on the body of a carpenter meant Cebu City Death Squad.
But derivatives and other forms of securities like compulsorily convertible debentures (CCDs) and optionally convertible debentures (OCDs) will continue to be governed by the existing provision of being taxed in Mauritius, Economic Affairs Secretary Shaktikanta Das told PTI here.