Patent ID: 7898926

Claim:
An optical pickup comprising: a plurality of light sources for projecting light beams having different wavelengths to a plurality of types of optical discs; an objective lens for collecting the light beam projected from each light source onto a recording layer of each optical disc; and a liquid crystal element for correcting spherical aberration arranged in front of the objective lens when seen from the light source; wherein the liquid crystal element includes a pair of substrates, a liquid crystal arranged between the substrates, a diffraction pattern including concentric diffraction electrodes formed on one substrate, and a phase shift pattern including concentric phase shift electrodes formed on the other substrate; the diffraction pattern and the phase shift pattern are arranged so as to face each other; the diffraction pattern includes a first region being of a constant range in a radial direction from a center, and a second region being arranged on the outer side of the first region; and an additional electrode facing the phase shift electrode is arranged in a gap between the diffraction electrodes in the first region.