In this paper a fast, yet accurate method to estimate the spectral and angular distribution of the scattered radiation of a fluorescent material is described. The proposed method is an extension of the adding-doubling algorithm for non-fluorescent samples. The method is validated by comparing the spectral and angular transmittance and reflectance characteristics obtained with the extended algorithm with the results obtained using Monte Carlo simulations. The agreement using both
methods is within 2%. However, the adding-doubling method achieves a reduction of the calculation time by a factor of 400. Due to the short calculation time, the extended adding-doubling method is very useful when fluorescent layers have to be optimized in an iterative process.