PROBLEM TO BE SOLVED: To provide an optical adapter that allows a pipe line inner face to be viewed from a front, and enables a correct observation of a coupling unit such as a T-shaped pipe line and the like of a destination where a tip of an insertion unit butts.SOLUTION: An optical adapter 10 attachably or detachably to or from a tip part 8 of an insertion unit of an endoscope comprises: an imaging optical path division member 20 that includes at least a first reflection plane 21 and second reflection plane 22 with a prescribed angle relative to a long side of the insertion unit reflecting subject light of a lateral part to thereby convert an angle of an imaging optical path and an exterior unit 13 that has the imaging optical division member 20 internally provided. The imaging optical path division member 20 has one of the first reflection plane 21 or second reflection plane 22 disposed so that the subject light on a front side of an insertion direction of the insertion unit further than the exterior unit 13 is incident upon an imaging optical system 30 provided in the tip part 8.SELECTED DRAWING: Figure 6COPYRIGHT: (C)2016,JPO&INPIT【課題】管路内面を正面視できるようにすると共に、挿入部先端が突き当たった先のT字管路などの接合部の観察が正確に行える光学アダプタの提供。【解決手段】内視鏡の挿入部の先端部8に着脱自在な光学アダプタ10であって、挿入部の長手方向に対して所定の角度を有した側方の被写体光を反射して撮像光路の角度を変換する少なくとも第1の反射平面21および第2の反射平面22を備えた撮像光路分割部材20と、撮像光路分割部材20が内部に設けられる外装部13と、を備え、撮像光路分割部材20は、第1の反射平面21または第2の反射平面22の一方が外装部13よりも挿入部の挿入方向の前方側の被写体光が先端部8に設けられた撮像光学系30に入光するように配設されている。【選択図】図6
