| 摘要 |
<P>PROBLEM TO BE SOLVED: To cancel an offset generated in a tracking error signal due to lens shift. Ž<P>SOLUTION: In a photodetector, a light receiving surface is divided into a plurality of light receiving areas by a first division line T2 that is either a first straight-line between lens shift directional lines of the respective light beams reflected by the respective layers other than a layer to be accessed and passing through a spot center provided in an area including a lens shift reference line of a signal light beam in the absence of the lens shift of an objective lens or a second straight-line, as a straight-line passing through the spot center, in which the absolute value of the sums of differences between the light receiving amounts of the light beams reflected by the respective layers other than the layer to be accessed at both sides of the straight-line is a local maximum value or the difference with the local maximum value is within a prescribed amount. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
|
