Abstract: An image scanner is disclosed which utilizes a dither plate to steer an image onto a sparsely-populated image sensor in order to effectively fill in the gaps between photosites. A DC motor, which is responsive to a servo control, is used to precisely position the dither plate relative to the image sensor. In order to provide a scanner which can scan at a rate compatible with a high throughput, a low inertia, low inductance motor is used to position the dither plate. The position of a dither plate is sensed by a linear proximity sensor which is part of a closed-loop servo control for the motor.

Abstract: Apparatus is disclosed for producing clock signals which are used to precisely control the modulation of a light beam by an acousto-optic modulator as it is line scanned by a moving mirror. The apparatus employs a set of spaced detectors which are located in the scanned beam path and respectively produce start-of-scan (SOS) and end-of-scan (EOS) signals. An oscillator which includes a delay line is responsive to the SOS and EOS signals to produce the clock signals. The delay line coupled to a NOR gate and flip-flop produces a delay line with the precise period .tau..