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:
Sep. 23, 2008
Filed:
Feb. 24, 2005
Taisuke Isano, Tochigi-ken, JP;
Taisuke Isano, Tochigi-ken, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A dielectric substrate having a refractive index nis covered with an amorphous dielectric medium having a refractive index nlarger than the refractive index n, and a rectangular grating is formed in the amorphous dielectric medium through an etching process. When microcrystal is formed in the amorphous dielectric medium through a thermal treatment to increase the refractive index n, a magnitude Δn of structure double refraction increases accordingly. Hence, a phase refraction ΔΦ of an irregular grating pattern in the rectangular grating becomes large without increasing a depth D of each trench of the rectangular grating, and thus it is possible to obtain an optical retardation plate having a fine periodic structure and having a desired plate retardation.