Photolithographic position measuring laser interferometer with relitively moving measuring intereometer

摘要

A laser interferometer for detecting the position of a moving object in a Y-direction when the object moves in an X-direction has a separating optical system that moves in the X-direction at a speed different from that of the moving object. A laser beam is separated by the separating optical system into a reference beam and a measurement beam, which are individually directed toward a reference mirror and a moving mirror on the moving object. The light of the measurement beam reflected from the moving mirror, and the light of the reference beam reflected from the reference mirror are received by a photodetector via the separating optical system, and the photoelectric conversion signal of the interference light is output as information concerning the position of the moving object in the Y-direction. A fixed mirror that is shorter than the moving object can be used because the separating optical system also moves in the X-direction.