JPS6443704A - Optical ic interferometer - Google Patents

Abstract

PURPOSE:To detect coordinate variation even when an object is in reciprocal motion by providing plural reference optical paths and light receiving elements, making the respective optical path lengths different at level smaller than wavelength, and detecting different interference states at the same time. CONSTITUTION:While the output of a light receiving element 63 for setting is detected, an optical path length adjusting device 90 is adjusted to make a lambda/4 difference between the phases of light waves which are emitted by a light emitting element 60 and reach the light receiving elements 61 and 62 for measurement through reference optical waveguides 52 and 53. Then, a light wave emitted by the element 60 is propagated in a projection optical waveguide 51 to travel toward a projection rod lens 70 and part of it enters the waveguides 52 and 53 halfway through directional couplers 80 and 81. The light beam emitted from the lens 70 is reflected by a corner prism 100 and incident on a branch optical waveguide 54 through a rod lens 71 for incidence. Then light waves branched to branch parts 54a and 54b are made to interfere with the light wave sent from the waveguide 51 and the outputs of the element 61 and 62 corresponding to the interference states are processed by a signal processing circuit. Consequently, the movement quantity of the prism 10 is measured.