Patent ID: 7440383
Filing Date: 2008-10-21
Classification: B82Y,G11B

Abstract:
1. An optical pickup device including an objective lens, with a numerical aperture (NA) not being less than 1, having a solid immersion lens which has a spherical portion and a flat portion parallel to the surface of an optical recording medium, said optical pickup device comprising: a light source configured to illuminate a light beam of a preset polarized state through said objective lens to said optical recording medium; and a photodetector configured to detect the component of the light reflected back from said optical recording medium in the polarized state perpendicular to the polarized state of the reflected light which prevails when the distance between the surface of said optical recording medium and said flat portion of said solid immersion lens is zero, the intensity of light detected by said photodetector being associated with the distance between the surface of said optical recording medium and said flat portion of said solid immersion lens.