Abstract

We present a method of optical measurement of the dynamic wetting, the dynamic contact angles, and the changes of the dynamic curved liquid surface corresponding to dynamic wetting, which uses the critical light reflection from dynamic curved liquid surfaces due to the dynamic wetting. When an expanded and collimated laser beam impinges on the dynamic curved liquid surfaces at glancing incidence, the special reflection patterns, which correspond to the different states of the dynamic wetting, are observed. Based on an analytic relation between the bright/dark region width and the height of down-/up-curved liquid surfaces, we proposed a method of optical measurement. In the experiment, a rod such as iron, copper, or aluminum is immersed at constant speed ($u=0.2\mathrm{mm}/\mathrm{s}$) into a liquid bath and withdrawn out gradually. We measured the changing curve of the dynamic contact angle of the iron rod and the characterization of the dynamic curved liquid surface of the iron rod.

© 2018 Optical Society of America

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