Measuring multiscale capillary curvature using laser beam self-interference

Abstract

When a parallel light beam illuminates a curved air–liquid interface, a group of self-interference fringes appears in the reflection field in the region near the critical point. A model describing the interface height and slope dependences on the fringe phase supports this observation. The fringe phase function is determined by the fringe image. The height, slope, and curvature of the interface curved by a glass slide and thin rod are measured. The resolution, for the curvature measuring, is up to 0.05μm−1. A comparison of the experimental results of the interface height by using the exponential theory verifies this approach’s reliability. A small RMS error shows that the results are in good agreement.