Patent ID: 6738323
Filing Date: 2004-05-18
Classification: B82Y,G11B

Abstract:
An optical disc apparatus which records desired data on a disc-shaped recording medium by near-field recording that uses an objective lens being held close to the disc-shaped recording medium, comprising a focusing control mechanism for keeping an interval between a surface of the disc-shaped recording medium and an exit surface of the objective lens at a prescribed value, the focusing control mechanism comprising:a light source for emitting a focusing laser beam having a prescribed wavelength; an illumination optical system for introducing the focusing laser beam to the objective lens and applying the focusing laser beam to the disc-shaped recording medium via the objective lens; a photodetecting optical system for detecting an interference light beam produced by interference between light reflected by the disc-shaped recording medium and light reflected by the exit surface of the objective lens, and outputting a light quantity detection result; and moving means for moving the objective lens along an optical axis thereof based on the light quantity detection result of the interference light beam.