Patent ID: 8437239

Claim:
An optical pickup for recording/reproducing information on/from an optical information medium having a plurality of information recording layers, comprising: a light source that emits light in a predetermined polarization state; a focusing lens group that includes a solid immersion lens having a flat surface portion parallel to a surface of the optical information medium and focuses the light; a first focusing unit that focuses reflected light obtained by reflection of the light focused by the focusing lens group from the optical information medium; a first photodetector that detects at least either a reproduction signal or a focus error signal by detecting a light quantity of reflected light from the optical information medium that has been focused by the first focusing unit; a second focusing unit that focuses reflected light obtained by reflection of the light focused by the focusing lens group from the flat surface portion of the solid immersion lens; and a second photodetector that detects a gap error signal corresponding to a distance between the surface of the optical information medium and the flat surface portion of the solid immersion lens by detecting a light quantity of reflected light from the flat surface portion of the solid immersion lens that has been focused by the second focusing unit, wherein an optical magnification ratio M of a first optical system including the focusing lens group and the first focusing unit and an optical magnification ratio m of a second optical system including the focusing lens group and the second focusing unit satisfy the condition M>m.