| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an objective lens capable of favorably correcting the aberrations both on and outside of the axis when recording or reproducing a 1st optical disk and a 2nd optical disk different in thickness, and improving productivity by avoiding poor transfer at the time of resin molding, and to provide an optical head device. <P>SOLUTION: In the case that a 1st annular aspheric surface 11a nearer to the optical axis 4 is projecting more than a 2nd annular aspheric surface 12a farther from the optical axis 4 in the objective lens, the difference w between the distance from the optical axis 4 up to the outer circumference of the 1st annular aspheric surface 11a and the distance from the optical axis up to the inner circumference of the 2nd annular aspheric surface 12a is set to be larger than 0 μm and not larger than 20 μm, and the step part 11 is tilted with respect to the optical axis. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
