Patent ID: 7502300

Claim:
An optical pickup, comprising: a first light source that emits a first light beam having a wavelength equaling λ 1 ; a second light source that emits a second light beam having a wavelength equaling λ 2 ; a third light source that emits a third light beam having a wavelength equaling λ 3 , the wavelengths λ 1 , λ 2 , and λ 3 satisfying λ 1 <λ 2 <λ 3 ; an optical system that directs at least one of the first light beam, the second light beam, and the third light beam onto an optical recording medium for a data recording/reproducing operation on the optical recording medium; a phase correction element having a phase shifting part that generates a phase shift for at least one of the first light beam, the second light beam, and the third light beam, said phase shifting part including a plurality of phase shifting regions arranged in a plane perpendicular to an optical axis of the light beam, different said phase shifting regions generating different phase shifts; a diffraction part that diffracts the light beam, said diffraction part including a plurality of diffraction regions, at least one of the plurality of phase shifting regions separating at least two of the plurality of diffraction regions, different said diffraction regions diffracting different amounts of at least one of the first light beam, the second light beam, and the third light beam; and an object lens that condenses the first light beam, the second light beam and the third light beam to the optical recording medium, wherein the object lens satisfies NA(λ 1 )=NA(λ 2 )>NA(λ 3 ), where NA(λ 1 ), NA(λ 2 ), NA(λ 3 ) are effective numerical apertures for the first light beam, the second light beam, and the third light beam, respectively, wherein a first beam diameter φ 1 of the first light beam, a second beam diameter φ 2 of the second light beam, and a third beam diameter φ 3 of the third light beam satisfy φ 2 >φ 1 >φ 3 , wherein the diffraction part generates a phase difference nearly equaling an integral multiple of 2π for one of the first light beam, the second light beam, and the third light beam, and wherein the diffraction part is formed in a first area corresponding to a beam diameter from φ 3 to φ 2 , and in a second area corresponding to a beam diameter greater than φ 3 .