Measuring
thicknesses in thin films with high spatial and temporal
resolution is of prime importance for understanding the structure
and dynamics in thin films and membranes. In the present work, we
introduce fluorescence-interferometry, a method that combines standard
reflected light thin film interferometry with simultaneous fluorescence
measurements. We apply this method to the thinning dynamics and phase
separation in free-standing inverse phospholipid bilayer films. The
measurements were carried out using a standard fluorescence microscope
using multichannel imaging and yielded subnanometer resolution, which
is applied to optically measure the discrete thickness variations
across phase-separated membranes
