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HOT TRENDS & TECHNOLOGIES IN BRIEF
DEFINITION
A charge-coupled device (CCD) is a specially made integrated circuit that responds to light. CCDs are used to capture and store image data in telescopes, scanners, bar code readers, and digital still and video cameras. A good CCD can produce an image in extremely dim light, and its resolution (i.e., sharpness or data density) doesn't degrade in low light the way those of film cameras do.
AT THE HEART OF today's digital imaging devices are charge-coupled devices (CCD). A type of semiconductor that's sensitive to light, a CCD consists of a 2-D array of individual elements, each of which is, in essence, a capacitor - a device that stores an electrical charge. (Thus explaining the D and one of the C's in the acronym.)
A CCD's charge is created when photons strike the semiconducting material and dislodge electrons. As more photons fall on the device, more electrons are liberated, thus creating a charge that's proportional to the light's intensity. With a 2-D array, you can capture an image.
Put another way, each CCD represents a single-image pixel. Today's best digital still cameras have sensors with up to 6 million pixels.
The challenge lies in reading these charges out of the array so they can be digitized. To do this, each individual CCD detector, or pixel, consists of three transparent polysilicon...