Spatially-resolved measurements of micro-deformations in granular materials using DWS

This article is a tutorial on the practical implementation of a method of measurement of minute deformations based on multiple scattering. This technic has been recently developed and has proven to give new insights on the spatial repartition of strain in a granular material. We provide here the basics to understand the method by giving a synthetic review on Diffusing Wave Spectroscopy and multiple scattering in granular materials. We detail a simple experiment using standard lab equipment to pedagogically demonstrate the implementation of the method. Finally we give a few examples of measurements that have been obtained in other works to discuss the potential of the method.