Fig. 1. Schematic representation of the experimental setup.

a An object hidden at a distance L_o behind a scattering medium emits light (e.g. because it is illuminated). The scattered light forms a speckle pattern, which is detected by a camera at a distance L_s from the medium (b). While the speckle itself looks random, its autocorrelation shows information about the hidden object (c). In the present experiment, we used L_o = 430 mm and L_s = 50 mm.