An approach to expand the beam coefficients for arbitrarily shaped beam
一种求解任意入射波束的波束因子的方法

We present an approach to expand the shaped beam in terms of the spheroidal wavefunctions in spheroidal coordinates for a spheroidal particle illuminated by off-axis arbitrarily shaped beam. The relations between shaped beam coefficients in spherical coordinates and the different range of mode are discussed. Once the beam-shape coefficients are determined, the solution of scattering for arbitrarily shaped beam by a homogeneous particle can be obtained.