Patent ID: 6798723
Filing Date: 2004-09-28
Classification: G11B

Abstract:
An optical pickup head, comprising:a light source for emitting a light beam; a diffracting means for creating a plurality of diffracted beams from the beam emitted by the light source; a converging means for focusing the plurality of diffracted beams from the diffracting means onto an optical storage medium; a beam branching means for branching a plurality of beams of the plurality of diffracted beams focused onto the optical storage medium and reflected by the optical storage medium; and an optical detecting means for receiving the beams branched at the beam branching means and outputting a signal corresponding to the amount of light of the received beams; wherein the optical detecting means has main beam light receiving portions for receiving zero order diffracted beams and sub-beam light receiving portions for receiving first or higher order diffracted beams of the plurality of focused diffracted beams; wherein the optical storage medium has a plurality of information recording planes and guide grooves are formed in at least one of the information recording planes; and wherein the amount of light of the first or higher order diffracted beams focused by the converging means when they are substantially focused on and reflected by a focus plane of the plurality of information recording planes is equal to or greater than the amount of light of the zero order diffracted beam focused by the converging means when it is reflected without focusing thereon by a non-focus plane other than the focus plane of the plurality of information recording planes.