This is a charge coupled device (CCD), SITE Model 002A, representative of those used with the Kitt Peak 4 meter telescope. These devices consist of two dimensional arrays of large numbers of tiny silicon diodes or picture elements (pixels). Those diodes convert light photons directly to electrical signals which are then processed digitally to produce images. The surface of this CCD contains an array of 2048 by 4096 pixels for a total of over eight million elements. Because of their enhanced sensitivity CCD's have almost completely replaced the use of photographic film in astronomy. This example was manufactured by Scientific Imaging Technologies Inc. and donated by them to NASM in 2000. It is now on display in the Explore the Universe gallery.
Gift of Scientific Imaging Technologies Inc.