Patent ID: 8264939
Filing Date: 2012-09-11
Classification: G11B

Abstract:
1. An optical pickup apparatus comprising: a laser diode configured to emit a laser beam; and an objective lens configured to condense the laser beam into a laser spot through which a signal recorded on a signal recording layer of an optical disc is read out by the laser beam, the objective lens including a lens surface, a portion of the lens surface having a first numerical aperture used for forming the laser spot, the lens surface formed with a second numerical aperture for acting as a lens, the second numerical aperture larger than the first numerical aperture in consideration of manufacturing tolerance of the objective lens, and the lens surface having formed thereon an anti-reflection coating which determines a transmittance of the laser beam so that the transmittance of the laser beam becomes maximum at a position of the second numerical aperture, wherein the first numerical aperture used for forming the laser spot is 0.85, and the second numerical aperture is at least 0.87.