Ce. Siewert, A RADIATIVE-TRANSFER INVERSE-SOURCE PROBLEM FOR A SPHERE, Journal of quantitative spectroscopy & radiative transfer, 52(2), 1994, pp. 157-160
A sphere-to-plane transformation technique and the spherical-harmonics
method are used to develop a solution to an inverse-source problem fo
r radiative transfer in a spherical body. It is assumed that, with the
exception of the inhomogeneous source term, all aspects of the radiat
ion-transport problem are known, and we seek to determine the source t
erm from a specified angular distribution of radiation that exits the
surface of the sphere.