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:
Jun. 20, 2006
Filed:
Nov. 08, 2000
Shoichi Takasuka, Osaka, JP;
Shin'ichi Ijima, Osaka, JP;
Hideyuki Nakanishi, Shiga, JP;
Akio Yoshikawa, Kyoto, JP;
Shoichi Takasuka, Osaka, JP;
Shin'ichi Ijima, Osaka, JP;
Hideyuki Nakanishi, Shiga, JP;
Akio Yoshikawa, Kyoto, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
An optoelectronic device that provides an excellent reproduction signal and a stable servo control while preventing deterioration of S/N ratio caused by stray light. The optoelectronic device has a semiconductor laser () that emits light beams on an information-recording medium (), a hologram optical element () having a diffraction grating region () and located between the semiconductor laser () and the information-recording medium (), and a photodetector () for receiving light that is diffracted at the diffraction grating region () of the hologram optical element (), among returning light beams from the information-recording medium (), and the optoelectronic device has also a diffraction grating region () in the vicinity of the diffraction grating region () of the hologram optical element () so as to prevent stray light other than diffracted light from the diffraction grating region () from entering the photodetector ().