Experimental investigation of liquid foams by polarised light scattering technique via the Mueller matrix

Experiments were conducted using well-controlled bubble size-distributed foam stabilised by Sodium Dodecyl Sulphate (SDS) solution to investigate the individual effect of liquid fraction of foam on the six independent normalised Mueller matrix elements via polarised light scattering technique. The liquid fraction, bubble size distribution and the Mueller matrix elements were measured individually during a foam free drainage process. It was found that the effect of foam properties on the Mueller matrix was more obvious when the foam was in a static state. Under the circumstance that the bubble size distribution was kept almost constant during the drainage process, the six independent normalised Mueller matrix elements showed dependence on the liquid fraction except N34, whereas N22 and N33 showed the highest sensitivity. In addition, N12 and N44 exhibited reflection symmetry in the static stage during foam draining. This suggests that only five independent Mueller matrix elements are sufficient to represent the current foam because of its axisymmetry.