Dynamic Speckle Correlations
نویسندگان
چکیده
Longand infinit range correlations C2 and C3 in the optical speckle pattern represent one of the most interesting phenomena in multiple scattering of light. Despite the strong scattering these correlations survive the averaging process of light diffusion and are even enhanced with increased randomness. In this article we are going to discuss the microscopic origin of these particular correlations which are explained in the simple picture of one and twofold crossing of multiple scattering paths. We present a comprehensive experimental study of dynamic speckle correlations,C2(t) andC3(t), where the phase shift between themultiple scattering paths is caused by the Brownian motion of the scattering particles. The shape and amplitude of the correlation functions C2(t) and C3(t) are in good overall agreement with theory. Deviations are found in the case of C2(t) when correlations are generated close to the incoming surface which can be explained by single scattering contributions.
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