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. 19, 2009
Filed:
Feb. 12, 2007
Masahiko Nishimoto, Osaka, JP;
Naoki Nakanishi, Shiga, JP;
Masayuki Ono, Osaka, JP;
Panasonic Corporation, Osaka, JP;
Abstract
An optical pickup device includes a diffraction grating for separating a light beam from a semiconductor laser into at least three light beams. The diffraction grating is partitioned into five areas each having a given periodic structure: a first area; a second area adjacent to the first area in a first direction; a third area adjacent to the first and second areas in a second direction; a fourth area sandwiching the third area with the first area; and a fifth area adjacent to the fourth area in the first direction and sandwiching the third area with the second area. The phase of the periodic structure of each of the first and fifth areas is ahead of that of the third area by substantially 90°. The phase of the periodic structure of each of the second and fourth areas is behind that of the third area by substantially 90°.