Scattering of Electromagnetic Radiation by a Large, Absorbing Sphere

Details are provided for two subroutines with which one can compute the various characteristics of the electromagnetic radiation scattered by an absorbing, homogeneous sphere of any reasonable size. The necessary expressions for this purpose were first derived by Mie. The method of computations used is the so-called method of logarithmic derivative of one of the complex functions, introduced by Infeld. The main difference between the two subroutines is in the procedure used in computations of one of the functions. This function is computed by an upward recurrence procedure in one subroutine and by a downward recurrence procedure in the other. Sufficient results for demonstrating the reliability of these programs are presented and discussed for a sphere of 10 µm radius illuminated by an unpolarized radiation of 0.4 µm wavelength.