| 摘要 |
PURPOSE:To generate accurate position signals of two condenser lenses with sufficient gains by detecting the positions of the condenser lenses to an optical head in the same direction with incident light when moving the condenser lenses and an optical path splitter in the same direction as that of the incident light. CONSTITUTION:The condenser lenses 24 and 7 are fixed onto a tracking movable part 4 so that they operates in the same way as shown by an arrow 14. When the condenser lens 7 shifts from the center of the optical head 1 as shown by an arrow 31, the incident light on a prism 22 enters one of two-split photosensors 18 more through the condenser lens 24 to indicate the deviation extent of the lens 7. The incident light to the photosensor 18 is stopped down by the condenser lens 24 into an extremely small spot, so even when the deviation extent of the condenser lens 7 is slight, the quantities of light incident to the sensors 18 vary greatly and the outputs of the sensors have larger conversion gains to the deviation extent than a conventional example which does not have the condenser lens 24. |
