Light scattering analysis with methods of geometrical optics for a particle arbitrarily positioned in a laser beam

The theoretical background for the light scattering analysis of a spherical and homogeneous particle with methods of geometrical optics is well known in case of a homogeneous electromagnetic field. Considering a common laser with a Gaussian beam, the field can be approximated as homogeneous only for a small area around the axis of the beam. Errors in the calculated amplitude and phase of the scattered field have to be expected for larger particles end particles outside this area. This problem occurs in the same way for the widely used Mie theory. A method will be presented, which extends the geometrical optics for the scattering in a laser beam with an inhomogeneous field distribution. Different scattering problems will be investigated and compared with results obtained on the basis of the Fourier-Lorenz-Mie theory.