Topological structures in vector speckle fields

We here demonstrate on both theoretical and experimental bases a method to recover the topological structure of a monochromatic optical field that has suffered diffuse transmission. This method consists of two steps: first, a linearly polarized sample beam is mixed with a coaxial Gaussian beam in orthogonal polarization states resulting in a Poincaré beam; second, a polarization-related spatial correlation function is considered and measured for the overall speckle field arising by optical diffusion. The singularities of the sample beam turn out to be imaged into the correlation function of the vector speckle field.