Patent ID: 7170846
Filing Date: 2007-01-30
Classification: G11B

Abstract:
1. A light receiving and emitting unit constituting an optical pickup optical system in which emitted beams from a plurality of light sources of different wavelengths are collected on an optical recording medium, and the returned beams from the optical recording medium are received, and then recorded on and reproduced from an optical recording medium; comprising: the plurality of light sources; a light receiving element; a light control unit including a voltage application area which allows emitted beams from the plurality of light sources to pass through first, constitutes part of optical paths of the emitted beams from the light sources and the optical paths of the returned beams from the optical recording medium, and controls at least one of the optical paths of the returned beams independently; and an optical block being in contact with the light control unit for allowing the emitted beams from the plurality of light sources to pass therethrough after having passed through the light control unit for guiding the optical paths of the emitted beams toward the optical recording medium, and diverging the optical paths of the returned beams from the optical recording medium from the optical paths of the emitted beams and guiding toward the light control unit; and wherein the optical block includes at least a first member, a second member, and a third member, the first and the second member is formed of a material having birefringent property, the third member is interposed between the first and the second members and formed of a material having lower refractive index than the first and the second members, the light control unit including a crystal thin plate having a plurality of refracting areas formed therein, the plurality of refracting areas which exhibit different refractive indexes from the surrounding area when a voltage is applied to a voltage application area, a pair of electrodes formed on the surfaces of the crystal thin plate so as to sandwich the crystal thin plate for applying a voltage to the voltage application area, and a first insulting member and a second insulating member for sandwiching the crystal thin plate so as to cover the electrodes.