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. 09, 2006
Filed:
Nov. 14, 2001
Hiroyuki Tadano, Kitakatsuragi-gun, JP;
Ikuo Nakano, Yamatokoriyama, JP;
Hiroyuki Tadano, Kitakatsuragi-gun, JP;
Ikuo Nakano, Yamatokoriyama, JP;
Sharp Kabushiki Kaisha, Osaka, JP;
Abstract
An aberration detection device which can detect a spherical aberration sensitively by separating a light beam appropriately so as to enlarge a difference in the positions where the respective separated light beams have the minimum spot diameters, and thus to enlarge a deviation amount of the focus positions of the separated light beams, is provided. A hologram for separating a light beam reflected from an optical disk and passing through a dual element objective lens into a first light beam and a second light beam, and a detection device for receiving the first and the second light beams and detecting the deviation of focus positions of the first and the second light beams, are equipped. The light beam directed to the hologram is separated into the first light beam and the second light beam, by a first region and a second region of the hologram which are obtained by being separated at a boundary drawn at an extreme value of a curve representing a wave front when the light beam has a minimum beam diameter on an information recording layer of the optical disk.