  Exploring and controlling the physical factors that determine the topography
of thin liquid dielectric films are of interest in manifold fields of research
in physics, applied mathematics, and engineering and have been a key aspect of
many technological advancements. Visualization of thin liquid dielectric film
topography and local thickness measurements are essential tools for
characterizing and interpreting the underlying processes. However, achieving
high sensitivity with respect to subnanometric changes in thickness via
standard optical methods is challenging. We propose a combined imaging and
optical patterning projection platform that is capable of optically inducing
dynamical flows in thin liquid dielectric films and plasmonically resolving the
resulting changes in topography and thickness. In particular, we employ the
thermocapillary effect in fluids as a novel heat-based method to tune plasmonic
resonances and visualize dynamical processes in thin liquid dielectric films.
The presented results indicate that light-induced thermocapillary flows can
form and translate droplets and create indentation patterns on demand in thin
liquid dielectric films of subwavelength thickness and that plasmonic
microscopy can image these fluid dynamical processes with a subnanometer
sensitivity along the vertical direction.
