| 摘要 |
<p>The mechanism consists of a movable optical objective assembly (1) attached to an assembly (6) which slides along two parallel guide rods (9) mounted in a fixed bracket (5). The bracket also acts as a magnetic path for the two permanent magnets mounted on it. The sliding assembly (6) carries two drive coils (8) attached to the optical assembly by leaf springs (21,22). Tetrafluorethylene bearings (10) are used between the sliding assembly and the rods (9). The light beam (20) is focussed along an optical axis (18) onto the data dots (19) on the surface of the rotating disc (2), with the help of mechanical focussing coils (23,24).</p> |
