publication detail
Interference patterns produced by an evaporating droplet on a horizontal surface
AUTHORS
Document type
Journal articles
Résumé
We study dynamical Newton-ring like fringes created by interfering Fresnel reflections of an evaporating sessile liquid droplet, which acts as a miniature convex lens. We show that conventional thin-film interference theory cannot be applied to explain the physical phenomenon. Because of the large thickness and curvature of the liquid droplet, the geometrical light paths of the reflected beams become very complicated and can no longer be considered approximately collimated. This results in interference fringes of concentric circles with different directional motion depending on the observation plane. The change in the interference pattern as a function of time is demonstrated by both simulation and experiment. This investigation allows us to fully understand the formation of interference patterns of an optical system having arbitrary thickness and curvature. In addition, by analyzing the high-contrast dynamic rings, we demonstrate nanoscale sensitivity to surface height changes of an evaporating water drop.