| 摘要 |
<p>An optical head device includes a collimating lens (9) or an aperture structure (13) which is disposed between a semiconductor laser (1) and a beam splitter (3;28) with the collimating lens or the aperture structure having an effective aperture smaller than an effective aperture of an objective lens (4). The device also includes a polarization aperture structure (11) and a quarter-wave plate (12) which, out of the light in a polarization direction, allow a portion of the light that is incident on an aperture portion whose diameter is smaller than the effective aperture of the objective lens to pass through, while allowing the remaining portion of the light to be diffracted, absorbed or reflected such that the light orthogonally directed thereto passes as it is through entire surfaces of the polarization aperture structure and the quarter-wave plate. The light passed is led to the optical detector without the reflected light being spatially lost. It is possible to increase a range of tolerance for the tilting of the optical disk, and to reduce any deterioration caused by the tilting of the optical disk. <IMAGE></p> |
