| 摘要 |
PURPOSE:To perform tracking control of focusing control without utilizing the mechanical displacement of an object lens, etc., by providing a variable-phase waveguide type optical deflecting element on the optical path of an optical pickup. CONSTITUTION:A laser beam L emitted from a semiconductor laser 2 is transformed to parallel rays by a collimate lens 4 and made incident on a variable-phase waveguide type optical deflecting element 14 by means of a cylindrical lens 12 after passing through a half mirror 6. The laser beam L made incident on the element 14 is subjected to phase changes in accordance with a tracking signal and focusing signal from a detector 10 at each electrode section 24 and 36 of an optical waveguide layer 30. The phase change can be performed by changing currents of constant-current sources A1-A4. Therefore, the deflection and focal point of the laser beam L can be made variable and tracking control and focusing control can be performed by displacing the focusing point of the laser beam L on the surface of an optical disk 22 by means of an object lens 20 through a reflecting prism 18 by utilizing the change in the deflection and focal point of the laser beam L. |
