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:
Feb. 04, 1997
Filed:
Dec. 13, 1995
Asahi Kogaku Kogyo Kabushiki Kaisha, Tokyo, JP;
Abstract
An objective lens system used in an optical system of an optical disk device. The objective lens system includes at least one lens element and converges light emitted from a light source onto a reflecting layer of an optical disk. The lens element has an offense against the sine condition OSC, and the optical disk has a substrate thickness T and a refractive index n. A ray of light exits the lens element and intersects an optical axis of the lens element at an angle .alpha.. The values of OSC, .alpha., n and T satisfy the following relationship for light rays that are incident on the objective lens system at distances from the optical axis of the objective lens system which are least equal to a predetermined percentage of an effective height of an aperture of the objective lens: ##EQU1## Accordingly, a spherical aberration of the optical system is corrected. An offense against the sine condition of only the objective lens is substantially coincident with a spherical aberration of the objective lens such that a coma of only the objective lens is corrected.