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:
Sep. 26, 2000
Filed:
Jun. 12, 1998
Applicant:
Inventors:
Assignee:
Pioneer Electronic Corporation, Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G02B / ; G02B / ; G11B / ;
U.S. Cl.
CPC ...
359719 ; 359721 ; 369 4423 ; 369112 ;
Abstract
An objective lens that allows spherical aberration to be suppressed during the reproduction of a CD without sacrificing reproduction characteristics of a DVD, has a first numerical aperture comprising a refracting surface that is in rotatory symmetry about an optical axis. A part of the refracting surface is displaced along the optical axis as an annular concave (or convex) portion centered on the optical axis. The annular concave (or convex) portion has a certain inner diameter r.sub.1 and a certain outer diameter r.sub.2 that reduce RMS aberration V to a value close to a minimum value. The annular portion has a certain depth (or height).