Precise Measurement of Clearance between Two Substrates Using Evanescent Waves

Abstract

In the material designing process of footwear outer-soles, the rubber grip property under lubricated conditions is important. Generally, friction behaviors of rubber under such conditions are influenced by contact states, which can be changed by various factors, i.e. viscosity, sliding velocity, normal force, surface roughness and wettability between two substrates. To discuss the influences of each parameter, the contact conditions are investigated. The purpose of this study is to establish a new method to measure the distributions of real contact area and film thickness between two substrates based on the decay behavior of an evanescent field in a total reflection method. In conclusion, film thickness was measured with an accuracy of 1 nm in a range of clearance of less than 800 nm.

Keywords

• in-situ measuring method
• contact condition
• evanescent field
• total reflection method
• light interferometry