A Green function formulation of the Extended Born approximation for three-dimensional electromagnetic modelling

We derive an Extended Born approximation for electromagnetic scattering from three-dimensional scatterers with arbitrary shape in the diffusive frequency regime. In order to improve on the accuracy of the original Extended Born approximation we present an alternative formulation using a Green function approach. Unlike the original formulation, the source proximity effect is included in the scattering tensor of the new Extended Born approximation. The resulting equations, which still have an explicit dependency with respect to the material properties of the scatterers, are solved via a numerical procedure and its computational cost is still of the same order as the first-order Born approximation. However, its solution is far more accurate.