Advances in surface-light-scattering instrumentation and analysis: noninvasive measuring of surface tension, viscosity, and other interfacial parameters

A new generation of vibration-mitigating surface-light-scattering instrumen tation has been designed and built. The computational application of an ins trument function derived by use of Fourier optics is presented. This instru ment and its accompanying suite of analysis software allow us to easily mak e accurate and noninvasive measurements of the interfacial tension, volume viscosity, and other interfacial parameters of fluids. We derived the neces sary surface response function algorithms to study both simple fluids and b inary fluids at their wetting transition and near their critical points. Th ese developments can be applied to study systems with liquid-vapor and liqu id-liquid interfaces, including spread monolayers, whenever optical access for a laser beam is available. (C) 2001 Optical Society of America.