Dual-beam incoherent cross-correlation spectroscopy

摘要: An incoherent dynamic light-scattering technique is developed to measure the local velocity and its statistics. By employing two parallel laser beams of different colors, measures cross-correlation function scattered intensities from separate illuminating volumes. Because there no phase coherence between beams, measured sensitive only intensity fluctuations caused by a seed particle that crosses in succession. The flow obtained transit time. We frame scattering theory so as account for two-beam geometry. Our experiment verifies calculation demonstrates applications technique. method has unique feature being able simultaneously opposite directions perpendicular incident beams. Its advantages are high spatial resolution accuracy, fast temporal response, ease use. useful studies turbulent flows, sedimentation heavy particles, phenomena complex fluids.