Patent ID: 7684306
Filing Date: 2010-03-23
Classification: G11B

Abstract:
1. An optical pickup apparatus for recording information onto a recording medium having a plurality of recording layers for recording information and/or reproducing information on the recording medium by irradiating the recording medium with light the recording medium, the optical pickup apparatus comprising: a light source for emitting light; a light-condensing unit for condensing light emitted by the light source onto one recording layer of the recording medium, the light-condensing unit changing a light-condensed position of the emitted light with respect to the recording medium by displacement of the emitted light in a direction perpendicular to an optical axis of the emitted light; a light-detecting unit having a plurality of light-receiving elements for receiving light reflected by the recording medium; and a light-splitting unit provided between the light-detecting unit and the light-condensing unit, the light-splitting unit having a plurality of divisions for diffracting the light reflected by the recording medium toward the plurality of light-receiving elements, the light-splitting unit comprising a division for diffracting at least first-order diffracted light among diffracted light beams obtained by reflection and diffraction on recording layers other than the one recording layer on which light is condensed by the light-condensing unit so as not to be directed either toward a light-receiving element for detecting track position information indicating information of emitted light condensing position to the recording medium in the direction perpendicular to the optical axis of the emitted light or toward a light-receiving element for receiving light used for obtaining the focus position information and another division for diffracting at least first-order diffracted light among diffracted light beams obtained by reflection and diffraction on recording layers other than the one recording layer on which light is condensed by the light-condensing unit so as to be directed toward said light-receiving element for receiving light used for obtaining the focus position information.