A low-cost surface laser light scattering spectrometer

A low-cost surface laser light scattering spectrometer for measuring interfacial tension and viscosity has been built and tested. The spectrometer is based on a cheap multimode semiconductor laser and an ordinary Si photodiode. In the case of fluids with moderate viscosities (e.g. hexane, ethanol and water) the spectrometer provides an accuracy as least as good as that obtained with the high-cost light scattering spectrometers proposed so far. Possible improvements of the spectrometer for expanding its range into the high viscosity region are discussed.