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. 29, 2013
Filed:
Apr. 28, 2011
Satoshi Inoue, Saitama, JP;
Shuichi Takeuchi, Saitama, JP;
Satoshi Inoue, Saitama, JP;
Shuichi Takeuchi, Saitama, JP;
Hoya Corporation, Tokyo, JP;
Abstract
A method for adjusting a tilt angle of an objective lens with respect to one of a multilayer optical disc having a plurality of recording layers and an optical axis of an optical information recording/reproducing apparatus, wherein a use wavelength λ and a numerical aperture NA are defined by conditions: 390<λ<420 and 0.75<NA<0.90. The method includes determining the tilt angle of the objective lens such that a spot quality defined through a predetermined transparent parallel flat plate matches a predetermined standard, and tilting the objective lens to have the determined tilt angle. When t1 represents a thickness of the predetermined transparent parallel flat plate and t2 represents a design protective layer thickness at which a coma caused when off-axis light is incident on the objective lens becomes smallest, t1 and t2 satisfy: −0.015<t1−t2<0.005.