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:
Apr. 18, 2006
Filed:
Apr. 21, 2005
Applicant:
Hideo Ukuda, Kanagawa, JP;
Inventor:
Hideo Ukuda, Kanagawa, JP;
Assignee:
Canon Kabushiki Kaisha, Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G02B 3/08 (2006.01);
U.S. Cl.
CPC ...
Abstract
An optical element of which diffraction efficiency hardly varies with wavelength is provided by using an optical material satisfying the conditions that n>−6.667×10ν+1.70 and θ≦−2×10ν+0.59 where nis a refractive index at d-line, νis an Abbe number at the d-line, and θis a second order dispersion at d-line, whereby diffraction efficiency is improved in any working visible wavelength region and more precise chromatic aberration correction is obtained.