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:
Feb. 21, 2012
Filed:
Mar. 11, 2009
Reona Ushigome, Utsunomiya, JP;
Reona Ushigome, Utsunomiya, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
The diffractive optical element includes a first diffraction grating and a second diffraction grating, which are formed of materials different from each other, the first diffraction grating and the second diffraction grating are stacked so as not to provide any air layer therebetween. The diffractive optical element satisfies conditions of nd1<nd2, νd1<νd2, 1.65≦nd1, νd1≦20, 1.73≦nd2, and 15≦νd2≦60 where nd1 and νd1 respectively represent a refractive index and an Abbe constant of the material of the first diffraction grating for a d-line, and nd2 and νd2 respectively represent a refractive index and an Abbe constant of the material of the second diffraction grating for the d-line. The element is capable of reducing deterioration of a diffraction efficiency by an obliquely incident light, to improve the diffraction efficiency of a designed order light in a use wavelength range.
Data source: USPTO (United States Patent and Trademark Office) public patent records. Weekly synchronization. How IDiyas builds this profile