The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 25, 1995
Filed:
Oct. 02, 1992
Koh Ishizuka, Urawa, JP;
Tetsuharu Nishimura, Kawasaki, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
An apparatus for measuring relative movement by the use of a diffraction grating includes a light beam generating portion generating a light beam including light wave components having planes of polarization orthogonal to each other, an interference optical system for directing the light beam from the light beam generating portion to the diffraction grating, the light beam directed by the interference optical system being diffracted by the diffraction grating to thereby at least create two diffracted light beams of different orders having planes of polarization orthogonal to each other, the interference optical system being disposed so as to superpose the two diffracted lights one upon the other or upon other light and cause them to interfere with each other, and a detecting system for detecting the interfering light beams from the interference optical system. The relative movement of the diffraction grating and the interference optical system is measured by the detection by the detecting system. The interference optical system has in at least a portion of the optical path from the diffraction grating to the detecting system a polarization maintaining optical fiber for propagating the two diffracted light beams therethrough.