| 摘要 |
Provided are an optical head device and an optical information recording/reproducing device, which can record/reproduce information to/from at least three kinds of optical recording media of different standards. A light beam emitted from a semiconductor laser is converged on a disk by an objective lens, and a reflected light beam from the disk is received by a photodetector. The optical system includes a liquid crystal refracting lens which can change the focal distance continuously within a predetermined range. The liquid crystal refracting lens has an electrode, and corrects, when the voltage applied to the electrode is changed, such a spherical aberration in the emitting light as changes with the kind of the disk. Moreover, a liquid crystal aperture control element has an electrode, and changes the effective numerical aperture of the objective lens in accordance with the kind of the disk, when the voltage applied to the electrode is changed.
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