Techniques for using the position sensitivity of silicon photodetectors to provide remote machine control

A concise review is given of position-sensitive devices for obtaining information on position of a workpiece and for remote machine control. Three types of silicon photodetector device are described: the quadrant cell, Wallmark diode, and Posicon ^TM diode. Performance of the Posicon diode is described and allowance for various sources of noise is made. Two models of the Posicon diode are discussed and their use as remote control devices is briefly discussed.