Large-area, low-noise amorphous silicon imaging system

Two dimensional amorphous silicon arrays can be used for medical imaging, non-destructive testing, and high-speed document scanning. We have built a 200 spi imaging system with an active area containing 2304 x 3200 pixels (29.2 x 40.6 cm(2)), the largest amorphous silicon imaging system described to date. Packaged with the array are peripheral electronics which include active matrix drivers, charge sensitive amplifiers, two 12 bit A/D converters, and control logic. Digital data travel via fiber to a frame grabber in a personal computer. Software includes gain/offset corrections, line and pixel corrections, window and level controls, and a user interface. Through a combination of layout optimization, amplifier design, and system timing, we have demonstrated a noise level of 1.5 KeRMS and a signal to noise ratio of 1900.