| 摘要 |
PURPOSE:To put even an endoscope with a dark optical system in focus with high precision by utilizing a light source at the outside of a photographic adapter for constituting a projecting means for focus detection, and moving and setting a photographic lens so that a photodetector has a minimum and maximum output level. CONSTITUTION:Light projected from a light source 32' is projected on an object 25 to be photographed through the optical observation system consisting of a light guide 33, pinhole 15, photographic lens 8, and endoscope 4. Reflected light from the object to be photographed returns to the photoelectric surface 17 of a photodetector 11 through the endoscope 4, photographic lens 8, and an image reforming lens 10. When it is considered that the photographic lens 8 is at a focusing position when the object to be photographed is at a position (b), image light is image-formed on a pinhole 15 and no light strikes the photoelectric surface 17. For this purpose, the photographic lens 8 is moved and set so that the output of the photodetector 11 is minimized, obtaining high-precision focusing. Further, the light source 32' is arranged at the outside of the photographic adapter, so the precise focusing detection of even the endoscope 4 with the dark optical system is performed with intense high-intensity lighting. |
