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. 31, 2011
Filed:
Feb. 28, 2007
Seima Kato, Utsunomiya, JP;
Chidane Ouchi, Utsunomiya, JP;
Seima Kato, Utsunomiya, JP;
Chidane Ouchi, Utsunomiya, JP;
Canon Kabushiki Kaisha, , JP;
Abstract
A measurement apparatus includes a first mask that is arranged on an object plane of a target optical system, and has a window that transmits measurement light, a second mask that has a reflection surface for reducing coherence of the measurement light, and a diffraction grating configured to split the measurement light that has been reflected on the second mask, has passed the first mask and the target optical system, wherein a distance Lg between the diffraction grating and an image plane of the target optical system satisfies Lg=m·Pg/λ where Pg is a grating pitch of the diffraction grating, λ is a wavelength of the measurement light, and m is an integer except for 0.