RESUMEN
The liquid deposition of thin films requires a thorough understanding of the underlying drying process, as it is an essential subprocess, where many defects may arise. To complement experimental studies, the present study uses a laser Michelson interferometer to visualize the vapor cloud of evaporating liquid films. The recorded interferometric patterns are evaluated using windowed Fourier filtering and a novel phase-unwrapping algorithm to allow for a robust analysis. Thin solvent stripes of different lengths are combined to yield a quantitative two-dimensional distribution of the solvent vapor concentration along a thin liquid stripe. The results show a considerable influence of natural convection during evaporation.
RESUMEN
In this work, we present the visualization of the internal flows in a drying sessile polymer dispersion drop on hydrophilic and hydrophobic surfaces with Spectral Radar Optical Coherence Tomography (SR-OCT). We have found that surface features such as the initial contact angle and pinning of the contact line, play a crucial role on the flow direction and final shape of the dried drop. Moreover, imaging through selection of vertical slices using optical coherence tomography offers a feasible alternative compared to imaging through selection of narrow horizontal slices using confocal microscopy for turbid, barely transparent fluids.
