Optical pickup lens

An optical pickup lens comprising:

• a first surface having a continuous shape on which a light beam from a laser light source is made incident;
• and
• a second surface opposed to an optical disc positioned at an opposite side against the first surface, the optical disc including an optical disc substrate and a light transmitting layer in the optical disc, wherein
• the optical pickup lens focuses the light beam having a wavelength of 410 nm or shorter from the laser light source onto the optical disc,
• the optical pickup lens is a single lens in which:
• a numerical aperture NA is equal to or larger than 0.84;
• a curvature radius r1 of the first surface is 0.7679574≦r1≦1.115539 mm;
• and a refractive index n for 405 nm wavelength is 1.52≦n≦1.5899, and
• the second surface has a convex aspherical shape on an optical disc side, having radii h1, h2, and h3 from an optical axis to a lens periphery side, where h1<h2<h3, and sags at the radii h1, h2, and h3, wherein the sags at the radii h1, h2, and h3 are sag1, sag2, and sag3, respectively, and differentials in the sag1, sag2, and sag3 are Δsag1, Δsag2, and Δsag3, respectively, where 0>Δsag1>Δsag2 and Δsag2<Δsag3.

An optical disc apparatus that reads out information from an optical disc by focusing a light beam having a wavelength of 410 nm or shorter from a laser light source onto the optical disc to form a light spot thereon through a collimator lens by using an optical pickup lens, the optical disc including an optical disc substrate and a light transmitting layer in the optical disk wherein

• the optical pickup lens is a single lens in which:
• a numerical aperture NA is equal to or larger than 0.84;
• a curvature radius r1 of the first surface is 0.7679574≦r1≦1.115539 mm;
• and a refractive index n for 405 nm wavelength is 1.52≦n≦1.5899,
• the optical pickup lens focuses the light beam from the laser light source onto the optical disc without passing through any diffraction ring zone,
• the optical pickup lens includes a first surface on which a light beam from a laser light source is made incident, and a second surface opposed to the optical disc positioned at an opposite side against the first surface, and
• the second surface has a convex aspherical shape on an optical disc side, having radii h1, h2, and h3 from an optical axis to a lens periphery side, where h1<h2<h3, and sags at the radii h1, h2, and h3, wherein the sags at the radii h1, h2, and h3 are sag1, sag2, and sag3, respectively, and differentials in the sag1, sag2, and sag3 are Δsag1, Δsag2, and Δsag3, respectively, where 0>Δsag1>Δsag2 and Δsag2<Δsag3.