| 摘要 |
An optical pickup device is equipped with a diffraction element that includes a transparent substrate. At least one surface of the transparent substrate is provided with a first region and a second region that encloses the first region. The surface is provided with a plurality of types of diffraction areas each of which generates predetermined diffracted light from only a light beam having a specific wavelength and permits other light beams having other wavelengths to pass through without diffraction. The first region is provided with each of the plurality of types of diffraction areas, while the second region is provided with only a diffraction area that generates the predetermined diffracted light from only a light beam having the maximum incident diameter among the plurality of types of diffraction areas.
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