| 摘要 |
An objective lens of an optical pickup for reproducing and/or recording information by condensing light to the information recording surfaces of first through third information recording media. The objective lens has a single lens structure and is used commonly for the first through third information recording media, and at least one optical plane of the objective lens is divided into at least two regions, a central region including the optical axis and a peripheral region surrounding the central region. A first diffraction structure is formed in the central region, and the objective lens condenses diffraction lights of the same order, out of the diffraction lights of first through third light beams generated in the first diffraction structure, respectively, onto the information recording surfaces of the first through third information recording media. A second diffraction structure is formed in the peripheral region, and the objective lens condenses diffraction lights of different orders, out of the diffraction lights of first and second light beams generated in the second diffraction structure, respectively, onto the information recording surfaces of the first and second information recording media.
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