Patent ID: 8427928
Filing Date: 2013-04-23
Classification: G11B

Abstract:
1. An optical head, comprising: an optical base; a light source that emits a light beam; an objective lens that condenses, in the form of converging light, the light beam emitted by said light source, onto an information recording medium; a cylindrical lens, onto which a reflected light beam that is reflected by the information recording medium is incident, and which generates astigmatism for forming a focus error signal; a light detector that receives the reflected light beam passing through said cylindrical lens; and a holder that holds said cylindrical lens and said light detector, said holder having a first main face and a second main face that extend in directions that intersect an optical axis of the reflected light beam, wherein said cylindrical lens is bonded to said first main face and said light detector is bonded to said second main face, wherein said holder is held by said optical base while said holder is configured to be adjusted in position with respect to said optical base in three perpendicular directions in a state that said cylindrical lens and said light detector are bonded to said holder, wherein an aperture is formed in said holder at a position at which at least part of the reflected light beam is incident, wherein said aperture has a dimension corresponding to a value that results from adding a dimension of the reflected light beam, a relative positional error between said cylindrical lens and said aperture, a relative positional error between said light detector and said aperture, and an increase in the dimension of the reflected light beam at the position of said aperture resulting from integrally adjusting said holder, said cylindrical lens and said light detector in an optical axis direction.