| 摘要 |
An optical pickup apparatus comprises an orbicular zone forming lens group 14 for forming the section of the laser beam, which is irradiated to an optical disc DK having plural recording layers, into an annular shape, a condenser lens 35 that converges the reflected beam from the optical disc DK, and a pinhole plate 36 having formed thereto a pinhole 36 a with a size corresponding to a flux diameter of the reflected beam converged by the condenser lens 35 . The orbicular zone forming lens group 14 refracts the laser beam irradiated to the optical disc DK so as to form the section of the laser beam into an annular shape in order that the internal diameter of the annular converged flux formed on the pinhole plate 36 a by the reflected beam from the recording layers other than the recording layer having an optical spot formed thereon becomes greater than the diameter of the pinhole 36 a.
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