Patent ID: 8451421

Claim:
An optical pickup apparatus comprising: a light source for emitting a light beam; a liquid crystal optical element constructed by combining in an integral fashion: a first liquid crystal layer for correcting aberration, said first liquid crystal layer having: a first rubbing direction; and a pre-tilt angle; and a second liquid crystal layer having a second rubbing direction, said liquid crystal optical element being mounted at a tilt angle with respect to an optical axis of said light beam, a direction of said tilt angle being a direction which cancels said pre-tilt angle; a transparent electrode for generating a potential difference across said second liquid crystal layer sufficient to control an amount of phase difference for said light beam passing through said second liquid crystal layer; and an objective lens for focusing the light beam passed through said liquid crystal optical element, wherein: said liquid crystal optical element is tilted at said tilt angle around a tilting axis, said tilting axis being perpendicular to said first rubbing direction; and an angle between said second rubbing direction and said first rubbing direction is determined in accordance with said tilt angle and said potential difference so that said second liquid crystal layer functions as an nλ/4 plate.