| 摘要 |
PURPOSE:To hold cavity between a tracking coil and a magnetic body member at a regulated level and to prevent magnetic flux form changing by forming a plane facing with the tracking coil of the magnetic body member faced with the tracking coil so as to correspond to the rotating radius of the tracking coil. CONSTITUTION:An opposite plane 15a to the tracking coil 5 of a yoke 15 of recessed shape is formed so as to correspond to the rotating radius of the tracking coil 5, enabling the cavity between the tracking coil 5 and the yoke 15 to be held constantly at a regulated level even in the turning of an optical system holding body 1 (coil 5). Thereby, a tracking control in an optical system can be performed with high accuracy. |
