Patent ID: 7106524

Claim:
An optical pickup apparatus for recording or reproducing data on a signal recording surface of a high-density optical medium that has the signal recording surface and at least one substrate, comprising: an optical module for generating and emitting collimated beams and receiving reflected beams from the optical medium; a solid immersion lens (SIL), arranged on an optical path between the optical module and the optical medium, having a first surface being planar and facing and closely spaced from the substrate of the optical medium, and a second surface being aspherical and facing the optical module, with the substrate being interposed between the first surface of the SIL and the recording surface of the optical medium, wherein the collimated beams from the optical module enter the second surface of the SIL, and are then focused through the SIL and the substrate onto the signal recording surfaces, and wherein a resultant numerical aperture of the SIL is proportional to a refractive index of the substrate of the optical medium.