High-resolution amorphous silicon image sensor

Thorsten Graeve; Youming Li; Andrew Fabans; Wingo Huang

doi:10.1117/12.237811

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11 April 1996 High-resolution amorphous silicon image sensor

Thorsten Graeve, Youming Li, Andrew Fabans, Wingo Huang

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Proceedings Volume 2708, Medical Imaging 1996: Physics of Medical Imaging; (1996) https://doi.org/10.1117/12.237811
Event: Medical Imaging 1996, 1996, Newport Beach, CA, United States

Abstract

This paper describes a new prototype a-Si (amorphous silicon) x-ray image sensor developed at EG&G Reticon. The sensor consists of a 512 by 512 array of a-Si photodiodes placed on 100 micrometer centers. The active area measures 5 cm on a side. Each pixel is addressed by a pair of switching diodes rather than the more common TFT (thin film transistor) switch. This approach leads to a simplified all-diode design with excellent fill factor, large dynamic range and good performance. The sensor is intended primarily for high-resolution x-ray imaging applications. A scintillator in direct contact with the diode array is used to convert incident x-ray photons to visible light detectable by the a-Si photodiodes. Since the conversion takes place directly at the sensor surface, no bulky intermediate optics are needed. The entire sensor plus support electronics can be mounted in a package less than 3 cm thick. The paper describes the sensor performance in terms of dark current, image lag, sensitivity and dynamic range. The MTF of the sensor and attached scintillator is measured by exposing the device through a narrow slit illuminated by a 50 kV x-ray source. Good contrast and sensitivity are achieved even at the Nyquist limit of the sensor resolution. Several images demonstrating the resolution and sensitivity of the sensor are presented.

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Thorsten Graeve, Youming Li, Andrew Fabans, and Wingo Huang "High-resolution amorphous silicon image sensor", Proc. SPIE 2708, Medical Imaging 1996: Physics of Medical Imaging, (11 April 1996); https://doi.org/10.1117/12.237811

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