Mainly optical methods for the accurate determination of thermophysical properties applicable for process-relevant conditions are developed and optimized. In addition to Dynamic Light Scattering (DLS), which has been continuously further developed by the research team for its application in the bulk of fluids (also called “conventional DLS”) and to interfaces (also called Surface Light Scattering, SLS), further techniques are currently being established at the institute. They include, e.g., the shadowgraph method for the simultaneous measurement of several transport properties in fluid mixtures as well as Laser-Induced Gratings (LIG, also called Forced Rayleigh Scattering, FRC) applied to the bulk of fluids and interfaces. Furthermore, Raman spectroscopy is used for the determination and monitoring of mixture compositions and for the analysis of molecular interactions, while the Beam Deflection Method and other approaches are used to determine the refractive index. Current conceptual studies also prepare the development of industrially applicable sensors based on light-scattering methods.