Photoelectric position encoder using diffraction imagery

摘要

A photoelectric position encoder using diffraction imagery has a laser light source emitting parallel, coherent light. As least one light sensing device senses the light amount received from the light source and provides an output signal corresponding thereto. A transfer slit plate having periodic slits is disposed between the light source and the light sensing device. The light sensing device thus senses the variation in the received light amount caused by the movement of the transfer slit plate. The light sensing device also senses brightness and darkness fringes of a diffraction image caused by the periodic slits of the transfer plate. Circuitry is coupled to the light sensing device and issues a position signal corresponding to the position of the transfer slit plate.