Transfer efficiency formula for diffusely reflecting laser pumping cavities

A method is presented for estimating the transfer efficiency of laser pumping cavities that have diffusely reflecting walls. The method is based on the assumption that the light inside the cavity is approximately isotropic. It is demonstrated that such a simplification leads to estimates of transfer efficiency that agree well with estimates obtained by Monte Carlo methods. Curves are given for the proportion of isotropic light absorbed by a cylindrical absorbing crystal as a function of the product of radius and absorption coefficient. This proportion is an important parameter in the transfer efficiency estimation.