We describe and test a refractive method for determining the height profile of an unsteady liquid-free surface, which is adequate for regions where the slope of the surface changes strongly, as for example the head of a spreading current. The method is developed for situations in which the height depends on a single Cartesian coordinate (plane flows); however, the underlying idea could be applied to more general cases. As a test, we obtained the profiles of a transparent solid object (a cylindrical lens) and of an actual liquid flow. These profiles are determined with high accuracy even if the direction of the normal to the free surface changes approximately 150° within the probed region.
© 1997 Optical Society of America
Luis P. Thomas, Roberto Gratton, and Beatriz M. Marino, "Profilometry of a liquid-free surface with large slope variations," Appl. Opt. 36, 2905-2911 (1997)