Radiative transfer through a spherically symmetric cloud of extincting particles - exact solution of the inverse absorption problem

We derive an exact solution to the inverse absorption problem to calculate the density distribution in spherical symmetry of absorbing particles from the intensity pattern obtained for homogeneous illumination. We illustrate the capabilities of the method by the simple example of a constant density core and find the required numerical effort to be negligible. The applicability is discussed for physical problems where unknown absorption coefficients, particle size or density distributions can be determined. from multi-frequency measurements of the transmission coefficient. The applications range from targets being evaporated by laser pulses to Bok globules in astrophysics. (C) 2002 Elsevier Science Ltd. All rights reserved.