| 摘要 |
An optical pickup device is constituted to enable stable recording or reproduction on/from a recording medium. The optical pickup device has an irradiation optical system for condensing a light beam using an objective lens, and comprises: a reflection portion disposed opposite the irradiation optical system, on a common optical axis therewith, and at a remove therefrom, for reflecting and returning the light beam toward the irradiation optical system; a phase plate disposed on the optical axis, for generating light on the optical axis, and light having a modified polarization state on all or a part of the periphery of the light on the optical axis, separately from the light beam; a detection optical system disposed on the optical axis, for extracting the light having a modified polarization state from return light of the light beam and guiding the extracted light to a photodetector; and a reflection portion driving portion for positioning the reflection portion on the basis of a photoelectric conversion output from the photodetector.
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