| 摘要 |
An objective lens used in the recording of a CD or a DVD, wherein a ringed step portion is provided in a first surface of an objective lens, the step portion is provided in a first surface of an objective lens, and the step portion producing a phase difference with respect to light having a first wavelength. In addition, a ringed step portion is provided in a second surface of the objective lens. The second step portion produces a phase difference with respect to light having a second wavelength.
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