Detector, Charge Coupled Device, 4 mp, Antireflective

This is a charge coupled device (CCD), SITE Model SI 424, representative of the CCDs used in the Sloan Digital Sky Survey camera. It is a 2.5-inch square chip containing a grid-like array of 2,048 x 2,048 silicon diodes, each one acting as a tiny picture element, or pixel, for a total of over 4 million pixels (4 megapixels). Each diode collects light and converts it into an electrical charge. This charge is transferred to a computer, retaining information on position and instensity, and the resulting image is viewed on a monitor or stored in a computer. The size and number of the silicon light detectors or pixels on the CCD determine the clarity or resolution of the final image. The surface of this back-illuminated CCD appears deep blue in color as a result of an antireflective coating. This example was manufactured by Scientific Imaging Technologies Inc. and donated by them to NASM in 2000.