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 ?
The addition of our VGA-size CMOS image sensors is a build on our successful low-power CIF-size CMOS image sensors, demonstrating our commitment to offering customers the flexibility to choose between a stand-alone image sensor or a complete camera SoC.
To date, CMOS image sensors have not had the technical capability to compete in the digital camcorder market; CCDs have dominated this entire market segment.
1) The industry's smallest and thinnest(1) lens module equipped with CMOS image sensor, lens and auto-focus functions in which the pixel structure and lens are optimally designed.
Advantest's new T2000 CMOS image sensor test solution incorporates a test head configured with a large optical source, and a new CMOS image sensor test module, providing illumination to an area greater than 10x that of Advantest's previous product.
The growing implementation of CMOS image sensors in dual camera mobile devices, tablets, and laptops has boosted the consumer electronics sector of the CMOS image sensor market.
Table 4: World Market for CMOS Image Sensors (2006-2007): Percentage Share Breakdown of Leading Players by Sales Value - Sony, Sharp, Avago Technologies Ltd, Toshiba, Matsushita, Sanyo, OmniVision, and Others (includes corresponding Graph/Chart) II-6
MagnaChip Semiconductor Launches VGA CMOS Image Sensor 49
Forza specializes in the design of advanced CMOS image sensors, from ultra-high resolution imagers for medical, broadcasting, scientific and military applications to low-cost sensors for digital cameras, cellular camera phones and other consumer devices.
As for assembly industry, Flextronics has become the largest camera phone module manufacturer in the world after it acquired the CMOS image sensor department of Agilent, and the image sensor testing plant of ASE; however, it does not have very efficient R&D.
BOISE, Idaho -- Enhancing its position as the world's leading supplier of CMOS image sensors, Micron Technology, Inc.
A new version of the IBIS5 CMOS image sensor with improved analog-to-digital converter (ADC) performance and a low-cost chip scale packaging option.
SPMT's employees include experienced technologists in CMOS image sensor, mixed-signal VLSI design, signal processing.