| 摘要 |
PURPOSE:To perform high-precision focusing detection by providing a projecting and a photodetecting means in such a way that an optical image formed after reflected on a subject side is formed to only an area within the range of a part of a visual field. CONSTITUTION:Illuminating light from a light source 7 is condensed by a condenser lens 11 to illuminate an end surface 8A with illuminating light with large intensity through an opening part 12A formed in the center of a stop 12, thus projecting the illuminating light with large contrast only on a small-area range 14 on the side of a subject 2 through a light guide cable 8 and a light guide 10. An ocular part 4, on the other hand, is equipped with a contrast detector 18 containing a photosensor 15, which has a beam splitter 18 on an optical axis behind the ocular part 4; and the eye is put close to behind the beam splitter 18 to observe an image within the visual-field range 10 of a visualfield mask 19, and an image forming lens 21 and the photosensor 15 are provided successively behind the optical axis 17' bent by the reflection of the beam splitter 18 to form the image of the subject 2 on a photodetection surface 15A sharply. |
