Analysis of time-correlated halos in scattering media for enhanced three dimensional imaging

In laser detection and ranging (LIDAR) we observed that, in a scattering medium, the target signature is overlaid by scattered light. Here, we distinguish back scattered light resulting in a strong background signal which decreases with the distance (power law) and light that is scattered on the return path producing a halo of light around the target. Both effects can impede accurate ranging and lead to an error in estimating the size and shape of the target. In this paper, we analyze the halos around a target located in a fog tunnel with varying fog density. The measurements were performed using time-correlated single photon counting. Hence, the occurrence of the halos was investigated spatially and temporally with a resolution of a few picoseconds. We have simulated photon propagation in the forward and backward directions, allowing us to explore the optical properties of the fog a such as the mean scattering length and the phase function. Furthermore, we can reconstruct the shape and position of the target by back-projecting the data building a Huygens-Fresnel wavefront.