Patent ID: 7804747

Claim:
A compatible optical pickup comprising: a first light source unit for independently projecting first and second short-wavelength laser beams that have different polarizations but the same wavelength; a second light source unit for independently projecting first and second long-wavelength laser beams that have different wavelength-range; a first objective lens that has a high numerical aperture suitable for a high density optical information recording medium; a second objective lens that has a low numerical aperture suitable for a low density optical information recording medium; and a light path changing unit for guiding the first short-wavelength laser beams to the first objective lens and guiding the second short-wavelength laser beams, the first long-wavelength laser beams, and the second long-wavelength laser beams to the second objective lens; wherein the light path changing unit has polarization selectivity so that the light path changing unit reflects the first short-wavelength laser beams and transmits the second short-wavelength laser beams with different polarization from the first short-wavelength laser beams.