| 摘要 |
<p>An objective lens for use in an optical pickup apparatus for recording and/or reproducing information on a first optical information recording medium having a protective substrate with a thickness t1 using a light flux with a wavelength »1, on a second optical information recording medium having a protective substrate with a thickness t2 using a light flux with a wavelength »2 and a third optical information recording medium having a protective substrate with a thickness t3 using a light flux with a wavelength »2, the objective lens includes: an optical surface including a central area and a peripheral area, wherein when the objective optical lens forms the portion of the light flux with the wavelength »2 passed the central area into a converged spot through a substrate with a thickness t4, the objective optical lens makes a spherical aberration of the converged spot a minimum value.</p> |
