RANGE-GATED AVALANCHE CCD IMAGER FOR SPACE BASED AND UNDERSEA APPLICATIONS

There currently does not exist a high resolution, high dynamic range, quantum limited detector of radiated emissions in the ultraviolet, visible, or near-infrared spectral regions. A proposal for a detailed design of an Avalanche CCD Imager and its supporting camera system is presented. The design provides a lwo noise gain mechanism that allows for quantum limited imaging performance to be realized in a CCD architecture. The Avalanche CCD Imager is capable of being 'gated' very rapidly with a 15 vold signal, making it ideal for undersea range-gated imaging. The Avalanch CCD Imager enables a cell-based amplification of photo-electrons. The detection device is realized by overlaying an amplifying semi-conductor structure, generally referred to an avalanche photodiode, directly on top of a charge coupled device structure. The resulting device is a hybrid of two mature tehcnologies, that, with certain provisions, allow the two technologies to function properly as a single integrated unit. The application of the proper voltage bias will effect avalanche conditions in each cell. Avalanche conditions can be turned off so as to effect high light level operation which may not require electron amplifications; avalanche conditions can also be varied so as to effect variable amplification and 'gating'. Finally, device driver circuitry, output amplification, analog-to-digital conversion, and statistically appropriate photon counting thresholding will produce a photon counting camera with well-characterizable performance properties. As a part of this Phase II program, SIT, Inc. will fabricate and test features of the Avalanche CCD. These test results will be used to design and model an Avalanche CCD Imager to meet the requirements of a Navy mission of interest. The device designed in this Phase I SBIR program will address the major technical challenges that, to date, have prevented the development of similar types of devices.