1. Method of detecting and analyzing movement in a scattering medium, said method comprising: projecting a coherent light towards said scattering medium; performing a spatial and temporal sampling of the electromagnetic field of the light scattered by said scattering medium, in order to obtain a plurality of images of said electromagnetic field, said plurality of images providing a plurality of speckle grain images which are representative with regard to the spatial sampling, at a given instant, of a state of the scattering medium, and representative in respect of the temporal sampling, of the evolution over time of the scattering medium; and analyzing the speckle grains resulting from said images obtained from said spatial and temporal sampling of the electromagnetic field of the scattered light, in order to detect and analyse a movement in said scattering medium, wherein the speckle grain analysis step comprises a step consisting in analyzing the vectorial inter-image distance.