Measurement of Water Distribution on Micro-structured Surface Buried in Water as a Model of Super Water Repellent Surface by Stimulated Raman Scattering Interferometer

Water repellency of surfaces is realized by the roughness of the surfaces and the coating compounds on the surfaces. It is known that the water repellent surfaces are due to invasion of water into the trench structures on the surface, or due to air remaining in the trench structures. However, for more effective designing and fabrication of water-repellent surfaces, it is essential to measure the spatial distribution of water around the microstructures. In the present study, the SRS interferometer developed by the authors is applied to distinguish whether water or air is present in the trenches on the water-substrate interface buried by water. By obtaining the SRS interference signal generated from water while scanning the sample position, the phase shift of the SRS interference signal due to the microstructure on the interface was observed. From the quantitative analysis of the phase difference, it was revealed that the trench was filled with water. It is concluded that SRS interferometry is an effective method to observe experimentally the interface condition with chemical contrast along microstructures.