| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an objective lens for an optical disk having a numerical aperture of ≥0.75, superior in terms of on-axis aberration, off-axis aberration and eccentric aberration between surfaces, and constituted of a bi-aspherical single lens. <P>SOLUTION: The objective lens is constituted of a bi-aspherical single lens having the numerical aperture of ≥0.75, and an angle formed by the normal line N to the 1st surface 1 and the optical axis at the highest incident point of light L0 is controlled to be equal to or smaller than one of 55°, 56°, and 57°. <P>COPYRIGHT: (C)2003,JPO |
