The relation of steady evaporating drops fed by an influx and freely evaporating drops

We discuss a thin film evolution equation for a wetting evaporating liquid on a smooth solid substrate. The model is valid for slowly evaporating small sessile droplets when thermal effects are insignificant, while wettability and capillarity play a major role. The model is first employed to study steady evaporating drops that are fed locally through the substrate. An asymptotic analysis focuses on the precursor film and the transition region towards the bulk drop and a numerical continuation of steady drops determines their fully non-linear profiles. Following this, we study the time evolution of freely evaporating drops without influx for several initial drop shapes. As a result we find that drops initially spread if their initial contact angle is larger than the apparent contact angle of large steady evaporating drops with influx. Otherwise they recede right from the beginning

Improvement of optical resolution in far-field imaging by optical multiplication

Based on the idea of the complex filters suggested by Toraldo di Francia in 1952, super-resolved imaging has been achieved by using interferometric image multiplication. The question of whether super-resolution implies a limited field of view is discussed, and an analytical criterion to decide this question is obtained. Three different imaging configurations are investigated, all of which gave a spatial resolution exceeding that corresponding to the full open aperture of the optical system. A resolution limit 55% of the Rayleigh limit was achieved for incoherently illuminated objects. One price that must be paid for the super-resolution is inefficient use of the light source. A second price is a limitation to the usable field of view