Patent ID: 6992966

Claim:
An optical pickup device comprising: a light source; an objective lens for converging a light beam emitted from the light source at a signal recording surface of an optical recording medium and irradiating the signal recording surface of the optical recording medium with the light beam; and first and second liquid crystal devices disposed in a light path between the light source and the objective lens for giving a predetermined phase distribution to transmission light that passes through each liquid crystal device, with both front and back surfaces of each liquid crystal device being flat surfaces; wherein each liquid crystal device includes a pair of transparent substrates and a liquid crystal molecule layer that is formed so as to be sandwiched between the pair of transparent substrates; wherein a liquid-crystal-molecule-layer-sandwiching side surface of at least one of the pair of transparent substrates of the first liquid crystal device has a shape that is formed such that a thickness distribution of the liquid crystal molecule layer in the first liquid crystal device is similar to a phase distribution that is produced when spherical aberration occurs due to an error in a thickness of a transparent layer that covers the signal recording surface of the optical recording medium; and wherein a liquid-crystal-molecule-layer-sandwiching-side surface of a least one of the pair of transparent substrates of the second liquid crystal device has a shape that is formed such that a thickness distribution of the liquid crystal molecule layer in the second liquid crystal device is similar to a phase distribution that is produced when coma aberration occurs due to tilting of the optical recording medium with respect to an optical axis of the objective lens.