| 摘要 |
PURPOSE:To minimize the forcible external force due to imbalance and to improve vibration characteristics by forming a rotationally moving part to the shape nearly symmetrical with a revolving shaft to approximately coincide the centroid of the moving part with the revolving shaft in order to improve the tracking accuracy of multibeams. CONSTITUTION:A roof prism 24 which is one of the optical parts of the rotationally moving part is fixed to a housing 26 by means of two pieces of bearings 25 and a prepressure spring 27. A motor for rotationally driving this roof prism 24 consists of flat coils 28a, 28b and magnets 29a, 29b. These magnets 29a, 29b are bisected and are mounted a housing 26. Two pieces of circular columnar magnets 31a, 31b are adhered and fixed to the surface of a holder 30 symmetrically with the revolving shaft. Iron screws 32a, 32b without having screw heads are disposed in two pieces of screw holes 26a, 26b provided in the housing 26. |
