Double-bounce multi-level physical optics algorithm for far-field scattering

The fast physical optics (FPO) algorithm for computing double-bounce scattering over ranges of aspect angles and frequencies is extended to encompass a three dimensional multi-level algorithm. Computations are performed within the framework of the physical optics approximation appropriate in the high-frequency regime. The proposed algorithm is directly applicable to monostatic configurations and a variety of double scattering settings.