| 摘要 |
An optical head according to an example of this invention has a polarization beam splitter, objective lens, photodetection element, first optical diffraction element, and second optical diffraction element. The first optical diffraction element is arranged on the optical path between the polarization beam splitter and objective lens. The first optical diffraction element passes a first light beam of a first wavelength and a second light beam of a second wavelength longer than the first wavelength through it, diffracts a first reflected light beam obtained from an optical disk in correspondence with the first light beam, and passes a second reflected light beam obtained from the optical disk in correspondence with the second light beam through it. The second optical diffraction element is arranged on the optical path between the polarization beam splitter and photodetection element, passes the first reflected light beam, and diffracts the second reflected light beam.
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