| 摘要 |
PROBLEM TO BE SOLVED: To fixedly build a diaphragm independently from a movable lens, etc. without particularly increasing the size of an objective optical system. SOLUTION: A diaphragm plate 34 in which a diaphragm 34a having a predetermined aperture size is formed, is arranged between movable lens frames 20 and 21 for constituting the objective optical system 11. A support member 35 formed in a substantially U shape is integrally provided with the throttle plate 34. This support member 35 is extended in the direction of a lens holding frame 14 for holding a subject side fixed lens group 15 in an optical axis direction. Its outer peripheral surface is brought into close contact with the inner surface of the objective optical system mounting unit 31 in a housing 30 over an angle of 180°or more in a circumferential direction. The supporting member 35 has an opening part 35a larger than the outer diameter of at least the movable lens frame 20 at its upper end part. A pair of left and right slits 36 are formed at the front side end of the support member 35 in its optical axis direction, and can be regulated in position in a rotating direction. COPYRIGHT: (C)2005,JPO&NCIPI
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