Tracking hidden objects using stochastic probing

Tracking trajectories of objects is conventionally achieved by direct beam probing or by sequential imaging of the target during its evolution. However, these strategies fail quickly when the direct line of sight is inhibited. Here, we propose and experimentally demonstrate real-time tracking of objects, which are completely surrounded by scattering media that practically conceal the objects. We show that full 3D motion can be effectively encoded in the statistical properties of spatially diffused but temporally coherent radiation. The method relies on measurements of integrated scattered intensity performed anywhere outside the disturbance region, which renders flexibility for different sensing scenarios as well as low-light capabilities.