PROBLEM TO BE SOLVED: To increase the removal performance for the residual liquid remaining on the observation window when the residual liquid is removed by air fed from the air/liquid feed nozzle.SOLUTION: A window surface 20a of an observation window 20 is protruded by a predetermined height from a flat portion 60 of a tip cover 31, and a sloped portion 61 is provided between the circumference of the window surface 20a of the observation window 20 and the flat portion 60 of the tip cover 31. Both at least a part of the flat portion 60 of the tip cover 31 and the window surface 20a of the observation window 20 are provided with a hydrophilic surface property, while the sloped portion 61 is divided into a plurality of partitions with different surface properties such that a hydrophilic partition 61a and a hydrophobic partition 61b are arranged alternately in a circumferential direction. This ensures that when the residual water remaining on the observation window 20 is removed by air fed from a nozzle 24, the residual water can be quickly moved from the observation window 20.SELECTED DRAWING: Figure 2COPYRIGHT: (C)2016,JPO&INPIT【課題】送気送液用のノズルからの送気によって観察窓に残留する残液を除去する際の残液の除去性能を向上する。【解決手段】観察窓20の窓面20aを先端カバー31の平坦部60から所定高さ突出させると共に、観察窓20の窓面20a周縁と先端カバー31の平坦部60との間に傾斜部61を備える。先端カバー31の平坦部60の少なくとも一部と観察窓20の窓面20aとを親水性の表面特性として、傾斜部61は、表面特性が異なる複数の区画に分け、親水性の区画61aと疎水性の区画61bとを周方向に交互に配置している。これにより、ノズル24からの送気によって観察窓20に残留する残水を除去する際に、残水を迅速に観察窓20から移動させることができる。【選択図】図2
