Patent ID: 7260047

Claim:
An optical pickup for recording or reproducing information with respect to first, second, and third recording media having information recording faces and light transmissive layers, the light transmissive layers of the first, second, and third recording media being formed on the respective information recording faces and respectively having thicknesses t 1 , t 2 , and t 3 , which are related to one another by t 1 <t 2 <t 3 , the optical pickup recording or reproducing information by focusing first, second, and third light beams of wavelengths λ 1 , λ 2 , and λ 3 , which are related to one another by λ 1 <λ 2 <λ 3 , on the respective information recording faces, said optical pickup comprising: an objective lens, movable in a substantially orthogonal direction with respect to respective optical axes of the first, second, and third light beams, for tracking the first, second, and third light beams on the respective information recording faces of the first, second, and third recording media; and a diffraction optical element, provided on an incident side of the first, second, and third light beams and movable with the objective lens, for diffracting and refracting the first, second, and third light beams so as to cause the first, second, and third light beams to be incident on the objective lens as diffracted rays of predetermined diffraction orders, said diffraction optical element causing the second and third light beams to be incident on the objective lens as diverging rays, and said diffraction optical element satisfying |Φinr|<|Φoutr|,and|ΦinIr|<|ΦoutIr| where Φinr and ΦinIr are degrees of convergence and/or divergence of incident rays of the second and third light beams, respectively, on the diffraction optical element, and Φoutr and ΦoutIr are degrees of convergence and/or divergence of incident rays of the second and third light beams, respectively, on the objective lens, and where the third light beam is incident on the diffraction optical element as a diverging ray.