| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical drive device capable of achieving a novel countermeasure against stray light. <P>SOLUTION: An optical drive device 1 includes: a lens system that focuses a light beam generated by a laser light source 2 on an access target layer of a multi-layer optical disk 11 among its plurality of recording layers, and focuses a reflected light beam which is the light beam reflected on the multi-layer optical disk 11 on a photo-detector 5; an astigmatism optical element 25 for applying astigmatism to the reflected light beam having passed through the lens system; and a polarization conversion optical element 31 arranged between the astigmatism optical element 25 and the focusing point of the astigmatism optical element 25. The reflected light beam includes a signal light component reflected by the access target layer and a stray light component reflected by the recording layers among the plurality of recording layers other than the access target layer. The polarization conversion optical element 31 is configured such that the polarization direction of the signal light component and the polarization direction of the stray light component are different from each other at least in a partial region of a spot formed in a light reception plane by the signal light component. <P>COPYRIGHT: (C)2013,JPO&INPIT |
