Path-length-resolved dynamic light scattering in highly scattering media

Based on single scattering theory and diffusing wave spectroscopy theory, low-coher-ence dynamic light scattering was used to investigate the path-length resolved light field intensity spectra of backscattering lights from different radius particles of colloidal suspensions. The linewidths of the measured light field intensity spectra were compared with the predict results calculated from the corresponding theories. The results show that in short path-length region, the measured linewidths well agree with that of the single scattering after considering the influences of wall-drag effect close to the interface. For different radius particles, the region with the path length about 5 times of the mean-free path length can be regarded as a single scattering region, while the region with the propagated path length larger than 225 m can be regarded as a diffusing region. It is demonstrated that the low-coherence dynamic light scattering can realize resolved path-length light field intensity spectra measurement from single scattering to diffusive scattering regions for dense suspensions.