| 摘要 |
PURPOSE:To detect focus with compact constitution, by detecting a light reflected on a half mirror formed around an optical axis by taking a lens near a pupil in a lens system as thick lens. CONSTITUTION:A lens L1 located near the pupil in a lens system is taken thick, the center of the lens L1 is plit with a surface 5, and this surface 5 is taken as a half mirror. The light coming from a ridge of the lens L1 reflected on the half mirror 5 out of lights from an object is formed at a detector 7 with a lens equivalent to a lens after the half mirror in the lens system, allowing to detect focus. |
