Second order fast Physical Optics

This paper shows a fast and efficient algorithm to compute the physical optics integral on smooth large surfaces of arbitrary shape. The algorithm is applied to several nurbs surfaces. The CPU time and accuracy is compared with the first order FPO. The algorithm consist of dividing the surface in smaller triangles and apply a quadratic approximation for each triangle. The contribution of each triangle is decomposed into different contributions. Some of the contributions can be computed using a closed form and some others can be computed numerically by integrating a slow varying function.