| 摘要 |
PURPOSE:To obtain a compact autofocusing device by utilizing Twyman interference method and executing focusing based on a change in a generated interference pattern. CONSTITUTION:The Twyman interference method for allowing a light beam radiated from a semiconductor laser 1 to interfere with reflected light from an image forming face 6a of an optical disk 6 is utilized. An interference stripe pattern generated by said method is changed in accordance with a distance between an image forming lens 5 and the reflecting face of the disk 6. Thereby, the interference stripe flowing direction is detected by two divided photosensors 7 to execute the focusing of the lens 5. Thus, the compact autofocusing device can be obtained. |
