Patent ID: 8098564
Filing Date: 2012-01-17
Classification: G11B

Abstract:
1. An objective lens for an optical pickup apparatus recording or reproducing information by converging a light flux with a wavelength λ 1 (380 nm<λ 1 <420 nm) emitted from a light source onto an information recording surface of an optical information recording medium, the objective lens consisting of: a single lens including at least one aspheric surface, wherein the objective lens satisfies following expressions: where Φ (mm) is an effective aperture at a light source side of the objective lens, d (mm) is a thickness on an optical axis of the objective lens, f (mm) is a focal length of the objective lens, NA is a numerical aperture at an image side of the objective lens, and n is a refractive index of the objective lens for the wavelength λ