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:
Apr. 29, 2003
Filed:
Apr. 02, 2001
Applicant:
Inventor:
Hiroaki Shimozono, Yokohama, JP;
Assignee:
Asahi Glass Company, Limited, Tokyo, JP;
Primary Examiner:
Int. Cl.
CPC ...
G11B 7/00 ;
U.S. Cl.
CPC ...
G11B 7/00 ;
Abstract
An objective lens used in the recording of a CD or a DVD, wherein a ringed step portion is provided in a first surface of an objective lens, the step portion is provided in a first surface of an objective lens, and the step portion producing a phase difference with respect to light having a first wavelength. In addition, a ringed step portion is provided in a second surface of the objective lens. The second step portion produces a phase difference with respect to light having a second wavelength.