6533b85bfe1ef96bd12bb392

RESEARCH PRODUCT

Three-dimensional dynamic light scattering

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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 fibre receivers. We show experimentally that the optimal signal-to-noise ratio (or intercept) β opt = 0.20, 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 influencing 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 ...