OPTICAL HEAD DEVICE, OPTICAL INFORMATION RECORDING/REPRODUCING DEVICE, ERROR SIGNAL GENERATION METHOD, AND FOCUS POSITION ADJUSTING METHOD

摘要

PROBLEM TO BE SOLVED: To provide an optical head device detecting displacement of the focal point of a second beam, the optical head device focusing a first beam and the second beam on the same focal point.

SOLUTION: The optical head device includes: a beam focusing means for focusing a first beam and a second beam on the same focal point in the state of facing each other; an astigmatism application means for applying astigmatism to the first beam passing through the focal point; and an optical detecting means for detecting the first beam having the astigmatism applied thereto. The optical detection means includes a light reception part for receiving the optical spots 100a to 100i of the first beam having the astigmatism applied thereto to output a signal. The light reception part includes a first dividing line 101 and a second dividing line 102 orthogonal to each other, a third dividing line 103 inclined with respect to the first dividing line, and eight light receiving areas 21a to 21h separated from one another by a fourth dividing line 104 inclined with respect to the second dividing line.

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