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:
May. 28, 2002
Filed:
Sep. 25, 2001
Applicant:
Inventors:
Assignee:
Hitachi, Ltd., Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G11B 7/12 ;
U.S. Cl.
CPC ...
G11B 7/12 ;
Abstract
An optical head having a plurality of laser light source and a plurality of photodetectors corresponding to the plurality of laser light sources. The plurality of laser light sources have at least three wavelengths with frequencies which are different from one another, a first laser module includes at least two laser light sources with two frequencies which are in close proximity and two photodetectors corresponding to the at least two laser light sources, and a second laser module includes another laser light source and another photodetector corresponding to the another laser light source.