ABSTRACT
For experimental applications, care should be taken that optical aberrations and distortions of the drop images are considered (i.e., corrected) in the calculation as far as possible. Image distortions have a rather strong influence on the resulting values because the calculated contact angles are very sensitive to the drop dimensions (see also Fig. 3). Usually, the total image distortions will be summarized into an aspect ratio factor, which has to be determined for each experimental set-up using, for instance, the procedure described in Ref. 35. Further care should be taken to ensure that the fibers are positioned at right angles to the microscope lenses to avoid extra image distortions.
