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. 18, 2000
Filed:
Aug. 22, 1997
Tetsuya Mori, Utsunomiya, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A positioning method for placing an object at a required position includes the steps of illuminating a grating mark formed on the object with a light beam from a light source, forming a mark coherent image corresponding to the grating mark on the surface of an image pickup means by using .+-.n-order light (n=1, 2, 3, . . . ) of reflected and diffracted light from the grating mark and superimposing a reference coherent image of a reference mark, having different periodicity from and no interfering connection with the mark coherent image, onto the image pickup means, and selecting a spatial frequency component of a beat signal inherent in a composite video signal formed by superimposition and detecting the position of the grating mark on the basis of the phase of the spatial frequency component.