Recently, the research team of Liu Honglin, Key Laboratory of Quantum Optics of the Chinese Academy of Sciences, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, collaborated with Professor Lihong V. Wang of Caltech has made progress in the propagation of light fields in macroscopic scattering media, and the relevant results are published in Optics under the title "Path sampling and integration method to calculate speckle patterns" Express。

　　Since the invention of laser, the speckle formed by coherent illumination through the scattering medium has received strong attentions, and has become the core of a large number of imaging technologies, such as imaging through the scattering medium, motion tracking, blood flow estimation, etc. However, due to the large number and random distribution of scatterers inside the scattering medium, tracking the propagation of the light field in the medium and calculating the scattering distribution of emitted light field has always been an impossible task. 

　　The researchers proposed a method to sample possible paths for a stationary scattering medium, then integrate all sampled fields. According to the probability function, paths are sampled with different weights, the light field corresponding to each path is recorded. Once sufficient optical paths are collected, a stable speckle pattern can be obtained. Aided by this method, the researchers calculated speckle speckles of a dynamic scattering medium and observed a negative exponential attenuation of the temporal correlation of speckles. The influence of anisotropic factors on speckle patterns was systematically studied, and it was found that the anisotropic factor increased and the speckle grains enlarged accordingly. By tagging different scattering components, it was also found that the doubly scattered light had a larger memory effect range than the singly scattered light, subverting the widely accepted cognition of the memory effect range.