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:
Nov. 18, 2003
Filed:
Mar. 28, 2000
Keiichi Matsuzaki, Osaka, JP;
Teruhiro Shiono, Osaka, JP;
Ken'ichi Kasazumi, Osaka, JP;
Tetsuo Saimi, Osaka, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
An optical head according to the present invention includes: a first light source for emitting light with a first wavelength; a second light source for emitting light with a second wavelength longer than the first wavelength; and an objective lens for focusing the lights with the first and second wavelengths on information recording surfaces of information recording media corresponding to the lights with the respective wavelengths. The objective lens is designed so as to reduce aberration with respect to the light with the first wavelength. An optical-path length from the second light source to the objective lens is allowed to be shorter than that from the first light source to the objective lens so that aberration caused by the objective lens due to chromatic dispersion caused by a material of the objective lens is reduced with respect to the light with the second wavelength. Thus, using a common optical system, recording and/or reproduction can be carried out with respect to the respective information recording media corresponding to the first and second wavelengths. Furthermore, since the common optical system can be used, the optical head can be simplified in configuration and can be reduced in size.