Patent ID: 7352517

Claim:
An optical pickup apparatus for conducting at least recording or reproducing of information on two types of optical information recording media having protective substrates with different thicknesses, comprising: a first light source for emitting a first light flux with a wavelength λ 1 ; a first objective lens for converging the first light flux from the first light source on an information recording surface of a first optical information recording medium having a protective substrate with a thickness t 1 when the optical pickup apparatus reproduces or records information for the first optical information medium; and a second objective lens for converging the first light flux from the first light source on an information recording surface of a second optical information recording medium having a protective substrate with a thickness t 2 (t 2 ≠t 1 ) when the optical pickup apparatus reproduces or records information for the second optical information medium, wherein the optical pickup apparatus satisfies: 0.8≦( f 1 ×NA 1 )/( f 2 ×NA 2 )≦1.2, where NA 1 is a numerical aperture of the first objective lens when the optical pickup apparatus reproduces information on the first optical information recording medium, f 1 is a focal length of the first objective lens when the optical pickup apparatus reproduces information on the first optical information recording medium, NA 2 is a numerical aperture of the second objective lens when the optical pickup apparatus reproduces information on the second optical information recording medium, and f 2 is a focal length of the second objective lens when the optical pickup apparatus reproduces information on the second optical information recording medium.