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. 26, 2016
Filed:
Oct. 28, 2011
Hidemi Takayama, Utsunomiya, JP;
Hidemi Takayama, Utsunomiya, JP;
CANON KABUSHIKI KAISHA, Tokyo, JP;
Abstract
A diffractive optical element that is used for an optical system includes a first diffraction grating and a second diffraction grating. The first and second diffraction gratings are disposed in contact with each other, one of the first and second diffraction gratings has a refractive index distribution and has a diffractive surface that includes a grating surface having a predetermined inclination and a grating wall surface having a predetermined height, and the diffractive surface has a shape in which an inclination of the grating surface of a diffraction grating having the greater refractive index distribution is decreased and a height of the grating wall surface is lowered with respect to a shape in which a phase difference based on a phase difference function that corrects an aberration of the optical system is added to a shape of a base surface that forms one of the first and second diffraction gratings.