  Accurate characterization using static light scattering (SLS) and dynamic
light scattering (DLS) methods mandates the measurement and analysis of
singly-scattered light. In turbid samples, the suppression of multiple
scattering is therefore required to obtain meaningful results. One powerful
technique for achieving this, known as 3D cross-correlation, uses two
simultaneous light scattering experiments performed at the same scattering
vector on the same sample volume in order to extract only the single scattering
information common to both. Here we present a significant improvement to this
method in which the two scattering experiments are temporally separated by
modulating the incident laser beams and gating the detector outputs at
frequencies exceeding the timescale of the system dynamics. This robust
modulation scheme eliminates cross-talk between the two beam- detector pairs
and leads to a four-fold improvement in the cross-correlation intercept. We
measure the dynamic and angular-dependent scattering intensity of turbid
colloidal suspensions and exploit the improved signal quality of the modulated
3D cross-correlation DLS and SLS techniques.
