| 摘要 |
PROBLEM TO BE SOLVED: To obtain a rigid mirror optical system which is good in peripheral image quality with an elongated insertion part by arranging a visual field stop for observation of an image of a specific range with respect to an effective image range of the max. outside diameter of an image transmission optical system between the image transmission optical system and an eyepiece optical system integrally with the eyepiece optical system. SOLUTION: This optical system consists, successively from an object side, an objective optical system O, the image transmission optical system RL, the visual field stop FS and the eyepiece optical system E. The visual field stop FS is used for observation of the image of the range smaller than the effective surface image range of 70% of the max. outside diameter of the image transmission optical system RL. The visual field stop ES and the eyepiece optical system E are integrally arranged. When the diameter of the effective image range is defined as B and the diameter of the image range to be used as A, the conditions 0.4<A/B<0.6 are desirably satisfied. If A/B is too small having 0.4 of the lower limit, brightness for practicable use is hindered. If A/B increases excessively beyond 0.6 of the upper limit, the sufficiently satisfactory correction of curvature of the field is not longer possible.
|
