| 摘要 |
<p>[PROBLEMS] To provide an optical head device and an optical information recording/reproducing device for recording/reproducing a signal on/from an optical recording medium having two-recording layers with no irregular track error signals by differential push-pull method even if the distance between the object layer and the non-object layer varies. [MEANS FOR SOLVING PROBLEMS] The light beam emitted from a semiconductor laser is split into a zero-order main beam, and ± primary-order diffracted light sub-beams by means of a diffraction optical element (3a). The light beams are applied onto a disk by an objective. The reflected light beam of the main beam from the disk and the reflected light beams of the sub-beams are received by photodetectors. From the outputs of the photodetectors, differential push-pull signals representing the differences between the push-pull signal by the main beam and the push-pull signal by the sub-beams are computed. The differential push-pull signals are used as track error signals. By using the diffraction optical element (3a), the sub-beams are Laguerre-Gauss beams.</p> |
