Pulsed Diffusing-Wave Spectroscopy in Dense Colloids

Abstract

A pulsed diffusing-wave spectroscopy (DWS) technique is introduced which substantially improves on the spatial resoln. and the interpretation of conventional DWS expts. With shorter light pulses it will be possible to observe ballistic particle motions, and more complicated systems in greater detail. The technique enabled explicit testing of a fundamental assumption of DWS theory, and can be applied in the important backscattering geometry where some of the diffusive assumptions are known to break down. This general idea of performing an autocorrelation measurement on optical grated photons can be extended to conventional quasielastic light scattering measurements. In this case the grating feature can be used to do optical ranging since there is no multiple light scattering. The article commences with a review of DWS.