Abstract
Several position sensing techniques have recently been developed for industrial applications such as mechanical alignment and kinematic calibration of industrial robots. The present article reviews position sensing techniques using diffraction and interference effects of laser light. Among them, two kinds of the position sensing techniques are described in detail. One is a technique using the FM heterodyne interferometry of a laser diode; the absolute distance from the interferometer to a reference point can be obtained from the beat frequency of the interference. The other is a technique using a small mark fabricated by a lithographic process; the position and posture of the object can be obtained from the light diffracted by the mark.
