| 摘要 |
PURPOSE:To set an objective lens to a prescribed position with high accuracy simply by providing a V-shaped groove at the peripheral of a lens frame of an objective lens and providing a projection energized elastically toward the V-shaped groove to a prescribed position on a moving member. CONSTITUTION:The V-shaped groove 15 is formed along the peripheral of the lens frame 50b. On the other hand, at a prescribed position of a tracking plate 80 being a moving member, a part of the tracking plate 80 is notched and bent in V-shape and a projection 85 being a projection body is projected inward and an elasticity is provided by the characteristic of the elastic material of the tracking plate. Several projections 85 are provided at an equal interval on a cylindrical tracking plate 80. In providing the structure above in advance, the lens frame 50b is inserted to the tracking plate 80 and then the projection 85 is engaged smoothly with the groove 15 along the V-shaped slope and fixed. Since mechanical engagement exists between the members, the optical perfor mance of the objective lens is not damaged because of an unexpected stress.
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