Patent ID: 8274876
Filing Date: 2012-09-25
Classification: G02B,G11B

Abstract:
1. 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, which includes an optical disc substrate and a light transmitting layer, through a collimator lens and an optical pickup lens, wherein the optical disc apparatus comprises, as the optical pickup lens, a single lens for focusing a light beam from the laser light source onto the optical disc without passing through any diffraction ring zone, in which: a numerical aperture NA is equal to or larger than 0.84; an effective diameter D satisfies 1.8 mm≦D≦2.45 mm; and a refractive index n for 405 nm wavelength light beam is 1.51≦n≦1.5899, the single lens comprising: 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 h