| 摘要 |
A single-element objective lens for an optical pick-up is configured to converge substantially parallel light rays incident thereon onto a data recording surface of an optical recording medium. The objective lens includes, a first surface, which is a light incident side surface, and a second surface, which is an optical recording medium side surface. The first surface is an aspherical surface having a positive power, and the second surface is an aspherical surface having positive or negative power. The objective lens is designed such that paraxial wavefront aberration is 0.07lambd rms or less when a decentering amount between the first and second surfaces is 2 mum or less so as to converge the incident light substantially to a diffraction limit. A numerical aperture of the objective lens is 0.8 or more.
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