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:
Jun. 29, 2004
Filed:
Mar. 08, 2002
Applicant:
Inventor:
Michio Matsuura, Kawasaki, JP;
Assignee:
Fujitsu Limited, Kawasaki, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G11B 7/00 ;
U.S. Cl.
CPC ...
G11B 7/00 ;
Abstract
A method is provided for performing data-writing or data-reading with an optical data storage medium including a substrate. The method includes the following steps. The storage medium is irradiated with light from a light source via an objective lens, so that a light spot is formed on the storage medium. Then, the lens is moved from the focus point to a predetermined defocus point where the light spot has a maximum peak intensity. The defocus point is detected as a minimum depletion point regarding the aberration caused by a thickness error of the substrate.