| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide the objective lens of two-group constitution whose numerical aperture is set as ≥0.8 so as to be applicable to an optical pickup system using a light source whose wavelength is about 400 nm, with keeping working distance is sufficiently secured even in the case that a focal distance is reduced so as to suppress chromatic aberration, the lens is easily manufactured by lowering manufacturing error sensitivity and possesses an excellent image height characteristics. <P>SOLUTION: The objective lens 3 is used in the optical pickup system 1 for recording or reproducing information for an optical disk 4, and is constituted of two positive lenses of a first lens 3a arranged on the side of the light source and a second lens 3b arranged on the side of the optical disk, and at least two optical surfaces including the first surface of the first lens that is the optical surface on the side of the light source and the third surface of the second lens that is the optical surface on the side of the light source are made as aspherical surfaces. <P>COPYRIGHT: (C)2004,JPO |
