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:
Aug. 13, 2019
Filed:
Mar. 02, 2018
Canon Kabushiki Kaisha, Tokyo, JP;
Hiroto Yasui, Saitama, JP;
CANON KABUSHIKI KAISHA, Tokyo, JP;
Abstract
Provided is an optical system including a front unit, an aperture stop and a rear unit which are arranged in order from an object side to an image side. The front unit includes a diffractive optical element, at least one first refractive optical element having a power in the same sign as a sign of a power at a diffractive surface of the diffractive optical element, and at least one second refractive optical element having a power in a different sign from the sign of the power at the diffractive surface. A partial dispersion ratio between a d-line and a C-line and a partial dispersion ratio between a g-line and the d-line of the at least one first refractive optical element and the at least one second refractive optical element are appropriately set.