Large area amorphous silicon x-ray imagers

Large two dimensional amorphous silicon imaging arrays are of interest for electronic document input and x-ray imaging. The device is a matrix-addressed array of light detectors fabricated from hydrogenated amorphous silicon on a glass substrate. Each imaging pixel consists of a light sensor and a thin film transistor (TFT). X-ray imaging is accomplished by placing a phosphor in contact with the image sensing surface, or by direct detection with a thick photoconductor. The imager technology is now capable of 10 in. arrays with image capture at greater than 10 frames/sec and with resolution of 4–6 lp/mm. We describe our new high resolution imaging system, comprising the sensor array with an active area of approximately 8 × 10 in. having nearly 3 million pixels, and the accompanying readout electronics. Key technological issues and alternative array designs are discussed.