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:
Nov. 29, 2011
Filed:
Jan. 22, 2009
Daisuke Koreeda, Saitama, JP;
Shuichi Takeuchi, Saitama, JP;
Yoshiyuki Tashiro, Kanagawa, JP;
Hoya Corporation, Tokyo, JP;
Abstract
There is provided an objective optical system used for information recording/reproducing for three types of optical discs. The objective optical system includes an objective lens, and a diffraction structure formed on an optical surface. The diffraction structure includes a first area for contributing to converging the third light beam. The first area includes first and second steps defined by first and second optical path difference functions, respectively. The first step is configured such that diffraction orders at which diffraction efficiencies for the first, second and third light beams are maximized are 1order, 0-th order and 0-th order, respectively. The first step satisfies a condition:−0.36×101+5.0×10×(1−3)<1.80×10  (1) The second step is configured such that diffraction orders at which diffraction efficiencies for the first, second and third light beams are maximized are 2order, 1order and 1order, respectively.