Optical pickup lens

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 h1, h2 and h3 from an optical axis to a lens periphery, the radii satisfying a first expression h1<h2<h3, wherein sags in the radii h1, h2, and h3 are sag1, sag2, and sag3, and differentials in the sags are Δsag1, Δsag2, and Δsag3, respectively, the differentials satisfying second and third expressions 0>Δsag1>Δsag2 and Δsag2<Δsag3,
• 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 h0 that matches the optical axis to an outer peripheral end, is first gradual, then abrupt, and gradual again before reaching the outer peripheral end, and
• 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.