| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical pickup lens which has a high NA and can secure longer working distance while having both of a good axial property and a good off-axis property. <P>SOLUTION: An optical pickup lens 1a is a biconvex single lens having a numerical aperture NA larger than 0.80 and in which a R1 plane 11 being near a laser beam source and a R2 plane 12 of an opposite side are convex type, a plane shape of the R2 plane 12 out of two planes is continuous shape, In the optical pickup lens, a radius h1, radius h2 and radius h3 (h1<h2<h3) torward an outer diameter of the lens from an optical axis are present, the radius h1, radius h2 and radius h3 satisfying inequalities 0>Δsag1>Δsag2 and Δsag2<Δsag3, wherein sag1, sag2 and sag3 denote respective sag quantity at the radius h1, radius h2 and radius h3, and wherein Δsag1, Δsag2 and Δsag3 denote change quantity of the respective sag, and the optical pickup lens has an abbe number vd of lens material of 50≤vd, a refractive index (n) of 1.59≤n≤1.62 in a wavelength of 405 mm. <P>COPYRIGHT: (C)2009,JPO&INPIT |
