This is a charge coupled device (CCD) designed specifically for use on the Imaging Spectrograph, one of the second-generation axial focal-plane instruments on the Hubble Space Telescope. The surface of this CCD contains a square array of 1024 by 1024 pixels for a total of over one million elements. The CCD has been specially treated to extend its sensitivity down to 2000 Angstroms.This dark hued, back-illuminated 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.CCDs are two-dimensional arrays of large numbers of tiny silicon diodes that convert light photons directly to electrical signals retaining information on intensity and location. These signals are stored and sorted by computer, and can be used in any application involving the analysis of light radiation.