Patent ID: 7692875

Claim:
An optical pickup comprising: a plurality of light sources for emitting a plurality of light beams including first and second light beams of respectively different wavelengths; an objective lens for converging the plurality of light beams; and a grating structure shaped axisymmetrically with respect to an optical axis of the objective lens, wherein, the objective lens and the grating structure cause p th -order diffracted light (where p is a non-zero integer) to be converged on an information layer of an optical disk corresponding to the first light beam, the p th -order diffracted light (where p is a non-zero integer) being formed from the first light beam by the grating structure; and the objective lens and the grating structure cause q th -order diffracted light (where q is a non-zero integer such that q≠p) to be converged on an information layer of an optical disk corresponding to the second light beam, the q th -order diffracted light being formed from the second light beam by the grating structure, wherein, the plurality of beams include a third light beam of a wavelength which is different from the wavelengths of the first and second light beams; and the objective lens and the grating structure cause r th -order diffracted light (where r is a non-zero integer such that r≠p) to be converged on an information layer of an optical disk corresponding to the third light beam, the r th -order diffracted light being formed from the third light beam by the grating structure.