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:
May. 26, 2015
Filed:
Nov. 18, 2008
Yuzo Seo, Kamakura, JP;
Chidane Ouchi, Utsunomiya, JP;
Takao Ukaji, Utsunomiya, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
An absolute position measurement apparatus measures an absolute position of an object to be measured using a first light source and a second light source which has coherency lower than that of the first light source. The absolute position measurement apparatus includes a measurement part which measures a point where phases of interference signals from the first and the second light sources coincide with each other or a point where an intensity of the interference signal from the second light source is maximized, an origin defining part which defines the point measured by the measurement part as an origin position, a phase storing part which stores the phase of the interference signal from the first light source at the origin position, an origin redefining part which redefines the origin position, and a position calculating part which calculates the absolute position of the object to be measured.