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. 13, 2004
Filed:
Jul. 11, 2000
Kenji Yamamoto, Tokyo, JP;
Kiyoshi Ohsato, Chiba, JP;
Sony Corporation, Tokyo, JP;
Abstract
An optical head comprising an objective lens having a large numerical aperture of 0.8 or more. The head further comprises a light source and an aberration-correcting lens group. To correct spherical aberration due to the manufacturing errors of an optical recording medium and lenses, to sufficiently correct chromatic aberration due to the use of a short-wavelength semiconductor laser and to correct aberration resulting from the use of the same optical system for light beams of different wavelengths, the objective lens is composed of two more lenses and has a numerical aperture of 0.80 or more and the aberration-correcting lens group is composed of a positive lens group and a negative lens group . The space between the positive lens group and negative lens group of the aberration-correcting lens group is changed, thereby to correct spherical aberration occurring at each optical surface of the optical system.