OPTICAL HEAD DEVICE, OPTICAL INFORMATION DEVICE, AND OPTICAL INFORMATION REPRODUCING METHOD

摘要

PROBLEM TO BE SOLVED: To realize a stable tracking control even if the rotational center of an information recording medium is not located on an extension line of the transfer direction of a light concentrating means.

SOLUTION: This optical head includes: a semiconductor laser for emitting a light beam; an objective lens 202 for concentrating the light beam on an optical disk 205; a transfer means for transferring the objective lens 202 between the outermost circumference and the innermost circumference of a recording area of the optical disk 205 along the optical disk 205; and a photodetector 214 for detecting the light beam returned from the optical disk 205. The photodetector 214 includes a plurality of areas divided by a division line. The division line is set parallel to the tangential direction of a track in the predetermined position on a transfer line 206 of the objective lens 202 between the outermost circumference and the innermost circumference of the recording area, and the plurality of areas are divided by a lateral division line which intersects the division line, respectively into a 1st area on which the light beam mainly including a tracking component is incident and a 2nd area on which the light beam not including the tracking component is incident.

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