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:
Oct. 26, 2010
Filed:
Mar. 02, 2006
Nobuo Ogata, Higashihiroshima, JP;
Nobuo Ogata, Higashihiroshima, JP;
Sharp Kabushiki Kaisha, Osaka, JP;
Abstract
An aberration detection device of the present invention is such that an absolute value of detection sensitivity of an aberration error signal is increased, and variation in detection sensitivity of the aberration error signal is little even when displacement between the center of light beam dividing means and the center of a bundle of light beams occurs due to a shift of a condensing optical system at the time of tracking control. A hologram element () divides light beams reflected from an information storage medium into at least two positive first order diffracted light beams. The hologram element () has a line (D) extending in a radial direction and passing through an optical axis (OZ) and a division line (D) having segments at least both ends thereof and a bulge in a center thereof, wherein the segments are substantially parallel to the line (D), and the bulge () bulges toward the periphery of the hologram element () so that a top (D) of the bulge () is substantially parallel to the line (D).