| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical disk device that uses an optical pickup lens with a high numerical aperture (NA) which can secure a longer working distance while having both good on-axis characteristics and off-axis characteristics.SOLUTION: The optical pickup lens 1a, being a single lens, focuses a light flux from a laser light source on an optical information recording medium. A shape of an R2 surface 12, of the two surfaces of the lens, on the opposite side to an R1 surface 11 closer to the laser light source is continuously formed. Further, when having radii represented by h1, h2, and h3 (h1<h2<h3) from an optical axis toward an outer diameter of the lens, where sag amounts in the radii h1, h2, and h3 are sag1, sag2, and sag3, and variations in the sags are &Dgr;sag1, &Dgr;sag2, and &Dgr;sag3, respectively, the shape of the R2 surface 12 has the radii h1, h2, and h3 satisfying 0>&Dgr;sag1>&Dgr;sag2 and &Dgr;sag2<&Dgr;sag3. |
