This study investigates the light scattering properties of colloidal suspensions at high concentration, focusing on the interference effects of multiple scattered electric fields. Concentrated fat emulsion samples with mass concentrations ranging from 1% to 45% were prepared, and time-resolved diffuse reflectance measurements were conducted using a femtosecond laser and a time-correlated single-photon counting system. The reduced scattering coefficient was obtained through inverse analysis based on the time-dependent diffusion equation. Experimental results showed that, while the reduced scattering coefficient increases linearly with concentration in the dilute regime, it exhibits nonlinear behavior at higher concentrations, peaking near 25% and subsequently decreasing. This trend is attributed to destructive interference among scattered electric fields in dense colloidal suspensions. To quantitatively describe this phenomenon, a modified model equation was proposed, accurately capturing the concentration dependence of the scattering coefficient in high concentration regimes. These findings contribute to a deeper understanding of optical phenomena in dense colloidal systems and provide crucial knowledge for the further development of optical techniques using scattered light
Sasaki et al. (Wed,) studied this question.