| 摘要 |
PURPOSE:To realize the optical detection with high accuracy and high linearity by providing a reflecting plate, a light shielding plate, etc. to the light emitting and photodetecting parts to obtain an optical position detecting means and attaching such detecting means to both the mobile and fixed parts respectively. CONSTITUTION:When the optical position detection is performed by means of a position servo loop, a mobile part moves toward the optical axis of an objective lens 5. Then the lens 5 and a bobbin 7 constituting said mobile part are moved, and therefore a reflecting plate 23 is also moved. As a result, the distance between the plate 23 and a light emitting part 22 is varied together with the distance between the plate 23 and a photodetecting part 24. Therefore the reflected light quantity produced by the plate 23 is varied together with the light quantity made incident to the part 24. Thus it is possible to detect the position shift of the lens 5 in the form of a change of the recived light quantity. This change is converted into a current at the part 24 and then into the voltage signal by an I/V converter 25. |
