Estimation of the correlation distance of one-dimensional random rough surfaces from polarization sensitive bistatic measurements

We present a scatterometer to estimate the correlation distance (CD) of a one-dimensional random rough surface from polarization sensitive bistatic measurements. The system, which constitutes our first effort to implement the variable coherence polarimetry (VCPol) technique, combines a source with controllable spatial coherence and polarization properties and a Stokes polarimeter. The working principle of the source is given by the generalized van Cittert-Zernike theorem for quasi-homogeneous, planar electromagnetic sources, which describes the propagation of the second-order correlation properties of the beam-like field generated by the source, allowing us to control the spatial coherence and polarization of the beam through the manipulation of the spectral density and polarization distributions of the source. Our results show that the CD can be correctly estimated for one-dimensional random rough surfaces with peak-to-valley distances comparable with the CD. However, if the peak-to-valley distance is small in comparison with the CD, the estimation obtained with our system is far from the actual value. Due to technical limitations, in the first stage of this project we were not able to build our system in a monostatic configuration, which is an appealing feature of VCPol particularly important in remote sensing applications. However, our future efforts will aim at building a scatterometer working in a monostatic configuration.