Gaussian beam scattering from rough dielectric objects at infrared and optical frequencies

The scattering of a Gaussian beam from an arbitrarily shaped dielectric object with a rough surface is investigated at optical and infrared frequencies using the plane wave spectrum method and Kirchoff approximation. The formulas of the coherent and incoherent scattering cross sections are obtained theoretically based on geometrical optics and tangent plane approximations. The infrared laser scattering cross sections of a rough sphere are calculated at 1.06 μm and the influence of the beam size is analyzed numerically. It is shown that when the beam size is much larger than the size of object, the results are close to those of an incident plane wave.