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.

CCD

(electronics)

CCD

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.
References in periodicals archive ?
Volcan currently processed the decanter underflow through a three-stage CCD circuit and is adding fourth and fifth stages (CCD 4 and CCD 5) to improve the recovery of dissolved metal.
Al Tamimi & Company recently assisted a manufacturer of a well-known brand of mobile and smart phone handsets in filing a complaint with the CCD and in conducting a very successful raid against an establishment offering counterfeit handsets for sale.
While many possible causes for CCD have been proposed, reported, and discussed--both in the scientific literature and popular media--no cause has been proven.
Our focus is on the design of an episode or monthly bundled case rate for CCD as an add-on to the visit-based, FFS physician payment system.
According to Richard Bredthauer, president of STA, the ultra high-resolution CCD chip was achievable due in part to the same advances in semiconductor fabrication that have enabled the increase of transistor density in microprocessors and memory chips, such as photolithography.
The measuring apparatus consists of laser, CCD camera, computer and competent software.
In addition, CCD technology produces a more precise spectral curve of color measurements, since the instrument is capable of reporting data at intervals of 0.
El Super CCD de 1a Generacion Generacion, comercializado por Fujifilm en el ano 2000, buscaba un equilibrio entre factores que diesen lugar a un superior rendimiento.
Today, more than ever, CCD is relentlessly driven to remain one of the top cutting die manufacturers in the world.
The camera features include a 2,400-by-1,800-pixel resolution CCD sensor, an equivalent Canon 35-100mm (2.
The new Super CCD HR (high resolution) incorporates a total of 6.
The SPECTRO CIROS CCD (CIRcular Optical System) is a solid state detector ICP-OES with continuous 1st Order wavelength coverage from 125 nm to 770 nm.