Multiple beam interferometry for measuring refractive indices and thicknesses of molecular thin films under normal and shear load
Prof. Dr. Markus Valtiner (Vienna University of Technology, Institute for Applied Physics)

Multiple beam interferometry (MBI) evolved as a powerful tool for the simultaneous evaluating of thin film thicknesses and refractive indices in Surface Forces Apparatus (SFA) measurements. However, analysis has relied on simplifications for providing fast or simplified analysis of recorded interference spectra. I will describe the implementation of new optics and a generalized fitting approach to 4x4 transfer matrix method simulations for the SFA and will describe a numerical approach for constructing transfer matrices for birefringent materials. This enables self-consistent fitting of thicknesses, birefringence and relative rotation of anisotropic layers, evaluation of reflection and transmission mode spectra, simultaneous fitting of thicknesses and refractive indices of ultrathin (molecular) layers confined between two transparent surfaces. I will showcase a variety of different topics including measuring refractive indices of confined fluids and organic thin films (e.g. lipid bilayers, liquid crystals and ionic liquids), the thickness of ultrathin films, the thickness of metal layers and the relative rotations of birefringent thin films during normal and shear load application.