Three-dimensional dynamic light scattering

Abstract

We describe the employment of a novel light-scattering scheme for the decorrelation of multiple scattering in strongly turbid samples. The three-dimensional scheme, which has been proposed already theoretically, shows certain advantages compared with the two-colour apparatus, which is commercially available. We describe our set-up in detail; features are the use of modern semiconductor laser diodes and contemporary single-mode ®bre receivers. We show experimentally that the optimal signal-to-noise ratio (or intercept) optˆ0 :20, which is obtainable with our set-up, can be quantitatively calculated from the measured uncertainties in the alignment. In particular, we give a detailed derivation of all factors in¯uencing the signal-to-noise ratio. We investigate a highly turbid polystyrene latex sample with a nominal radius of 57.5 nm and 5% solid content, to demonstrate clearly measurements of the cross correlation function without distortions due to multiple scattering. With its turbidity of 3 mm ¡1 at 790 nm this represents the most turbid sample which has been investigated by dynamic light scattering to date.

Instrumentation on Multi-Scaled Scattering of Bio-Macromolecular Solutions

“…Since the two beams had different wavelengths, the two detectors should be set at different scattering angles to receive scattered photons with the same momentum transfer. While the two-color method was proven to be capable of obtaining significant beating efficiencies (intercept, or β > 0.6), it had very strict requirements on optical alignment [ 16 ]. Subsequently, the 3D cross-correlation method was proposed to preserve the merits of the cross-correlation idea, yet making alignment more feasible in practice [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ].…”

“…We now present an exciting method that can simultaneously use three-dimensional photon cross correlation function (3D-PCCF) [ 3 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ] measurements in combination with synchrotron X-ray scattering. 3D-PCCF can experimentally extract single scattering behavior from a reactive bio-macromolecular solution in the presence of multiple scattering.…”

In vivo measurement of skin blood microcirculation using diffusing wave correlation technique

“…where τ is the time delay, also known as a lag time; β is the dimensionless parameter (0 ≤ β ≤ 1), so called aperture function 26 or correlation function 'interception', 27 and is depended on the number of detected speckles and coherence properties of incident radiation.…”

Speckle dynamics under ergodicity breaking

“…The brute force method combining Monte Carlo modeling, multi-exposure speckle imaging (MESI) and spatial frequency domain imaging (SFDI) has been implemented [18,19]. Also, a dedicated experimental procedure with a dual laser source and multiple detectors allowing isolation of the single scattering contribution from the total scattered signal has been described [20][21][22]. Experimental procedures using an ergodic reference sample, for instance by slowly rotating the sample during the experiment [23], or using a second cell filled with dynamic material placed behind the sample (second cell randomizes and gently shakes the speckle pattern of the static sample) [24] are used to treat non-ergodicity.…”