Patent ID: 7697401

Claim:
An optical head device comprising: a light source for emitting a light beam; a light converging means for converging the light beam onto an optical disk; a light converging spot moving means for moving a position of a focus of a light converging spot formed by the light beam converged by the light converging means, in a direction perpendicular to a recording surface of the optical disk; a light beam splitting means for splitting the light beam converged by the light converging means and reflected from the optical disk into a plurality of split light beams; and a light sensing means which includes at least one photoreceptor including a plurality of split light receiving areas, the light sensing means outputting an electric signal corresponding to a light amount of the split light beam entering each of the plurality of split light receiving areas or an electric signal corresponding to a combined light amount of the split light beams entering the plurality of split light receiving areas; wherein the plurality of split light beams split by the light beam splitting means includes a circular ray or a pair of semi-circular rays; and at least two annular rays or at least two pairs of semi-annular rays, which are rays outside the circular ray or the semi-circular rays.