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:
Jun. 17, 2014
Filed:
Apr. 13, 2012
Reona Ushigome, Utsunomiya, JP;
Reona Ushigome, Utsunomiya, JP;
Canon Kabushiki Kaisha, , JP;
Abstract
A diffractive optical element is made by layering first and second diffractive gratings. A difference of an extinction coefficient to d-line between the two materials of each of the first and second diffractive grating is larger than 0.0002 and smaller than 0.002. The following conditional expressions are satisfied 0.05<|Δnd1|<0.3, 0.05<|Δnd2|<0.3, 20<|Δνd1|<40, and |Δνd2|<15, where Δnd1, Δnd2 are differences of a refractive index to the d-line between the two materials of the first and second diffractive gratings, and Δνd1, Δνd2 are differences of an Abbe number between the two materials of the first and second diffractive gratings.
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