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:
Jan. 02, 1996
Filed:
May. 13, 1994
Masakazu Matsugu, Tokyo, JP;
Kenji Saitoh, Yokohama, JP;
Jun Hattori, Zama, JP;
Sakae Houryu, Hachiohji, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A method of detecting a relative positional deviation of a first object having a first grating mark with an optical power and a second object having a second grating mark with an optical power, is disclosed, wherein a projected radiation beam is diffracted by the first and second grating marks in sequence and, on the basis of a position of convergence on a light receiving surface of plural diffraction beams produced by the diffraction through the first and second grating marks and including a signal beam having been diffracted at a predetermined order by each of the first and second grating marks, the relative positional deviation is determined, a detection zone is defined on the light receiving surface, the signal beam is converged upon the detection zone, and a predetermined diffraction beam of the plural diffraction beams which, for a relative positional deviation of the first and second objects, shows displacement different from that of the signal beam is substantially prevented from being converged upon the detection zone.