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:
Oct. 02, 2012
Filed:
Dec. 09, 2008
Satoshi Inoue, Saitama, JP;
Daisuke Koreeda, Saitama, JP;
Shuichi Takeuchi, Saitama, JP;
Hoya Corporation, Tokyo, JP;
Abstract
There is provided an objective lens for information recording/reproducing for three types of optical discs, which includes a first area contributing to converging a third light beam onto a record surface of a third optical disc. The first area includes a phase shift structure having refractive surface zones concentrically formed about a predetermined axis. The phase shift structure includes first and second step groups. The first step group is configured such that an optical path length difference ΔOPD(nm) given by each step of the first step group to a first light beam satisfies a condition: 2N+1.10<|ΔOPD/λ1|<2N+1.40, where Nis an integer or zero, and the second step group is configured such that an optical path length difference ΔOPD(nm) given by each step of the second step group to the first light beam satisfies a condition: 2N−0.10<|ΔOPD/λ1|<2N+0.10, where Nis an integer.