| 摘要 |
PROBLEM TO BE SOLVED: To deal with integration by constituting the movement of a parallel plate glass for correcting spherical aberration with precision required by an optical system and in a small size. SOLUTION: If an optical disk 6 is one with a substrate thickness of 0.6mm, an electric current is flowed in a driving coil 15 so that a parallel plate glass 9a is positioned over the optical axis of a light beam; if the optical disk 6 is one with a substrate thickness of 1.2mm, a reverse current is allowed to flow through the driving coil 15 so that a parallel plate glass 9b is positioned over the optical axis of the light beam. Consequently, a rotor 9 is rotatably moved by an interaction between the generated magnetic field of the driving coil 15 and the magnetization of a permanent magnet 17. |
