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:
Feb. 14, 1995
Filed:
Apr. 05, 1993
Koh Ishizuka, Ohmiya, JP;
Tetsuharu Nishimura, Kawasaki, JP;
Hiroshi Kondo, Yokohama, JP;
Yasushi Kaneda, Tokyo, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A displacement information detection apparatus for detecting relative displacement information regarding the apparatus and an object to be detected includes an illumination system for radiating coherent light. A first diffraction grating splits the coherent light from the illumination system into first and second light beams, which are radiated onto the object. A second diffraction grating synthesizes the first and second light beams emerging from the object to generate an interference light beam. A light-receiving element detects the interference light beam and detects the relative displacement information regarding the object and the apparatus upon reception of the interference light beam. The illumination system is configured to focus the first and second light beams at a location along an optical path between the first diffraction grating and the second diffraction grating, so that the interference light beam incident on the light-receiving element is a divergent light beam.