| 摘要 |
<P>PROBLEM TO BE SOLVED: To achieve a stable tracking control by producing a tracking signal without an offset even for a multi (three or more than) layer disk. <P>SOLUTION: Each of receiving sections 253 and 254 of a main region light receiving section group 25b is disposed between a projection line 341a and a projection line 347a which a stray light from information layers out of a plurality of information layers adjacent to an information layer on which a light beam condenses forms by projecting a third dividing line 235 on a light detector 220 and a fourth dividing line 236 on the light detector 220, respectively. Further, each of light receiving sections 251 and 252 of a sub region light receiving section group 25a is disposed between a projection line 342a and a projection line 343a which the stray light from the information layers out of a plurality of the information layers adjacent to the information layer to which the light beam condenses forms by projecting a first dividing line 231 onto the light detector 220 and a second dividing line 232 onto the light detector 220, respectively. <P>COPYRIGHT: (C)2008,JPO&INPIT |
