US Patent 7616550 Optical pickup unit

An optical pickup unit is disclosed that comprises a first light-emitting element capable of emitting first-wavelength light; a second light-emitting element capable of emitting second-wavelength light whose wavelength is different from that of the first-wavelength light; a polarizing mirror transmitting or reflecting the first-wavelength light and reflecting the second-wavelength light; a first objective lens converging the first-wavelength light on a first medium; and a second objective lens converging the first-wavelength light or the second-wavelength light on a second medium.