Patent ID: 7724632
Filing Date: 2010-05-25
Classification: G11B

Abstract:
1. An optical pickup device comprising: a light source; a condenser lens for condensing a light beam emitted from the light source onto the recording surface of an optical recording medium; and a liquid crystal element including liquid crystal and transparent electrodes arranged in a manner sandwiching the liquid crystal, the liquid crystal element being disposed between the light source and the condenser lens, wherein the liquid crystal element is disposed for compensating for spherical aberrations generated in two light beams having different wavelengths from each other and different effective diameters on the condenser lens from each other, at least one of the transparent electrodes of the liquid crystal element is divided into a plurality of areas in a concentric manner, so that a voltage is individually applied to each of the plurality of areas; and when a first light beam is one of the two light beams having a larger value of the effective diameter, a second light beam is the other having a smaller value of the same, and the spherical aberration generated in the first and the second light beams are first and second spherical aberrations, respectively, among the plurality of areas, areas that are located inside and outside the effective diameter of the second light beam, and between which a same voltage can be applied when the first spherical aberration is compensated are connected electrically so as to have the same potential.