Patent ID: 8248900
Filing Date: 2012-08-21
Classification: G11B

Abstract:
1. An optical disc apparatus for irradiating a disk-shaped recording medium with first and second light beams emitted from a same light source so as to be focused to a same focus position from opposite surfaces of the disk-shaped recording medium respectively by way of corresponding first and second objective lenses to record a standing wave, comprising: a first controller that controls a position of the first objective lens according to a returning light beam from a reflection layer arranged in the recording medium; a detector that detects the first or second light beam emitted from either the first objective lens or the second objective lens, transmitted through the recording medium, and made to enter an other of the first objective lens or second objective lens; and a second controller that controls a position of the second objective lens so as to make a focus position of the first objective lens and a focus position of the second objective lens agree with each other according to an outcome of detection by the detector.