Patent ID: 7034947
Filing Date: 2006-04-25
Classification: G01B,G01D

Abstract:
1. An interference measuring apparatus including: an optical system for dividing a coherent light beam into two light beams, causing said divided two light beams to pass along discrete optical paths and making them into linearly polarized light beams orthogonal to each other and modulating to the phase of the wave front of at least one of them, and again superposing the wave fronts of said linearly polarized light beams one upon the other; an optical member for converting the superposed light beams into a linearly polarized light beam of which the polarization azimuth rotates; a light dividing member for dividing said linearly polarized light beam of which the polarization azimuth rotates into a plurality of light beams; a grating plate having different polarization transmitting properties in conformity with the incidence positions of the plurality of light beams; and a plurality of light receiving elements for individually receiving the light beams transmitted through said grating plate, a plurality of different interference phase signals being provided by the reception of lights of said light receiving elements.