| 摘要 |
PURPOSE:To enable small size and high accuracy, by locating the incident end of the photo conductive number along with the flat plane including the schuduled focus plane of optical system and tilted to this plane and giving the emitting end of the conductive member to the photo detector consisting of charge transfer elements. CONSTITUTION:The incident end lnoa of optical fiber lno at almost center of the optical fiber train arranged in one row is located at the position through the light axis 0 of the optical system 3 on the scheduled focus plane 4 of the optical system 3 to detect the focus matching. The respective incident end of the optical fiber train includes the scheduled focus plane 4 and it is located along the plane tilted to this plane and receives light for the image formed before and after the focussed plane. The illuminance signal corresponded to the image formed on the scheduled focus and/or before and after the plane is selectively picked up from the photo detector 2 and is compared, allowing to detect the direction and amount of the shift in the focus of the optical system 3 from the scheduled focus plane 4. |
