Laser interferometer

摘要

A laser interferometer wherein a laser beam emitted from a laser device at a fixed position impinges on an optical lens mounted on a movable member, and interference fringes are produced on a semitransparent mirror formed at an end of the optical lens opposite to the laser device. The interference fringes on the semitransparent mirror are converted to electrical signals by a photoelectric transducer including a bundle of optical fibers arranged along concentric circles and photodiodes located opposed to the end surface of the bundle of optical fibers. Based on the electrical signals from the photoelectric transducer, the number of the interference fringes passing by and the direction of movement of the interference fringes are detected to determine a relative distance between the laser device and the optical lens.