Patent ID: 6952390

Claim:
An optical pickup apparatus, comprising: a first light source for emitting a first light beam having a first wavelength λ 1 to reproduce and/or record information from or onto a first optical information recording medium having a first protective substrate of a first thickness t 1 ; a second light source for emitting a second light beam having a second wavelength λ 2 (λ 2 >λ 1 ) to reproduce and/or record information from or onto a second optical information recording medium having a second protective substrate of a second thickness t 2 (t 2 ≧t 1 ); a plurality of optical elements, each of the optical element having a plurality of optical surfaces, wherein the optical elements are arranged on a common optical path through which the first light beam and the second light beam pass; a first phase modulator having discontinuous parts formed periodically and concentrically around an optical axis on at least one of the plurality of optical surfaces, each of the discontinuous parts being formed from a predetermined number of stepped portions, wherein the first phase modulator gives a diffraction effect only to the first light beam; and a second phase modulator having discontinuous parts formed periodically and concentrically around an optical axis on at least one of the remaining optical surfaces, each of the discontinuous parts being formed from a predetermined number of stepped portions, wherein the second phase modulator gives a diffraction effect only to the second light beam.