Patent ID: 7742383
Filing Date: 2010-06-22
Classification: G02B,G11B

Abstract:
1. An optical pickup lens with a numerical aperture of 0.84 or larger for focusing a light beam of a collimated light or a weak finite light in a coherent wave-front state from a laser light source with a wavelength of 410 nm or shorter on an optical information recording medium in such a state that, as off-axis characteristics, an aberration becomes 15 mλrms or smaller when the angle of view is 0.3 degrees, the optical pickup lens being a biconvex single lens with a first surface from which the light beam from the laser light source enters without passing through any diffraction ring zone and a second surface opposite to the first surface, the first surface and the second surface having convex shapes, wherein the second surface has a continuous shape, a shape of the second surface of the optical pickup lens having radii h the second surface has a convex-shaped portion in its center part and does not have a concave-shaped portion in a periphery thereof so that a slope (Δsag), from a lens center h when a single lens center thickness is d and a focal length of an objective lens is f, 0.9≦d/f≦1.2 is satisfied.