Target recognition in a turbid medium with backscattered polarization patterns

摘要

Optical systems have been extensively studied for target recognition in a turbid medium because of its promising applications in many fields such as driver assistant system. Several recent studies have demonstrated that relevant information of the turbid medium including the hidden object in the medium can be derived by analyzing the polarization state of diffusely backscattered light of the sample. In this paper Stokes/Mueller formula was introduced to investigate polarized light transportation in a turbid medium such as atmosphere; Mie scattering theory was applied to calculate the scattering property of polarized light; Monte Carlo method was used to compute backscattered polarization patterns from a turbid medium containing hidden object. Results showed that the backscattered polarization patterns are strongly influenced by optical parameters of the medium. The two-dimensional distribution of degree of polarization (DOP) calculated from backscattered Mueller matrix can well discriminate different objects within limited distance. For applications in driver assistant system, the effective recognition distance in a foggy weather was also calculated; and results could be several times of visibility distance.