Patent ID: 8098352

Claim:
An optical pickup apparatus comprising: a light source for emitting a light beam; a liquid crystal optical element having a first liquid crystal layer for correcting aberration and a second liquid crystal layer functioning as an nλ/4 plate in an integral fashion, said liquid crystal optical element being disposed at an angle relative to an optical axis of said light beam, said angle being in a direction that cancels a pretilt angle of said first liquid crystal layer; a transparent electrode for generating a potential difference on said second liquid crystal layer in order to control an amount of phase difference for said light beam passing through said second liquid crystal layer; an objective lens for focusing the light beam passed through said liquid crystal optical element; and a driver for driving said transparent electrode so as to generate a potential difference that is the lowest among a plurality of potential differences that cause an area of said second liquid crystal layer which includes at least an effective diameter of the light beam to function as an nλ/4 plate.