| 摘要 |
<P>PROBLEM TO BE SOLVED: To simultaneously suppress a quality deterioration in a focus error signal (S-shaped signal) while suppressing a quality deterioration in a lens error signal resulting from stray light in a multilayer disk. <P>SOLUTION: An optical disk drive includes a diffraction element 12 on which reflected light from an optical disk recording medium is made incident, having a first diffraction region Mc formed at a position for diffracting light of a central part of an incident light flux, second diffraction regions C formed so as to come into contact with the outer edges of the first diffraction region, and third diffraction regions A, AA formed so as to come into contact with outer edges of the second diffraction regions. The optical disk drive also includes a light reception and signal generation part for generating a focus error signal and generating a lens error signal by a spot size method on the basis of light diffracted by the third diffraction regions A, AA. <P>COPYRIGHT: (C)2013,JPO&INPIT |
