| 摘要 |
PROBLEM TO BE SOLVED: To realize the miniaturization of a strabismus optical device, the facilitation of assembly and the improvement of optical performance by holding a visual field direction changing prism in the form that the outer periphery part of the prism may come into contact with the inner peripheral surface of a strabismus outer frame and one end of the prism may come into contact with one end of an objective outer frame. SOLUTION: The field direction changing prism 3 and the objective outer frame 9 are held by the strabismus outer frame 8 so that their outer periphery parts may come into contact with the inner peripheral surface of the frame 8 and also one end of the prism 3 may come into contact with one end of the frame 9. Therefore, the prism 3 is made larger than the conventional one without making the strabismus optical device large in size. Then, a 1st reflection surface 3b of the prism 3 is provided in the direction where it is lowered with respect to an image-formation optical axis (c) distance is separated). Therefore, since an object side optical axis c' is lowered downward than a conventional object side optical axis c'', a light beam passing through nearest to a metallic coat side does not enter an interference range even when off-axis luminous flux is thick.
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