Developmental solid-state imaging system

A developmental imaging system has been constructed as part of a long-term program to develop a high quality, high performance, all solid-state television camera for NASA. The purpose of the developmental system is to provide a test and demonstration vehicle for solid-state mosaics developed on the program and to obtain limited operational information in a nonlaboratory environment. The system, loosely packaged in an 8½-by-8½-by-10 inch volume including display sweep generator circuits, utilizes commercially available integrated circuit logic cards, discrete FET sampling switches, and a 100-by-128 element mosaic developed on the program. The "camera" provides a dynamic range of approximately five to seven shades of gray and operates on 6 volts at variable frame rates between 6 and 60 frames per second at light levels of 0.1 to 1 foot-candle, respectively. As of March, 1968, the system had been in operation for approximately one year without failure. This imaging system exhibits frame integration sensitivity due to storage of light-generated charge carriers in each phototransistor's collector-base depletion layer during the periods between its readout sampling. Fabrication of the sensor matrix and mechanization of the interrogation system for image readout from the mosaic are described. Considerations affecting imaging resolution, spectral response, responsivity dynamic range, and quantum efficiency are discussed.