  A simple model for the estimation of the light yield of a scintillation
detector is developed under general assumptions and relying exclusively on the
knowledge of its optical properties. The model allows to easily incorporate
effects related to Rayleigh scattering and absorption of the photons.The
predictions of the model are benchmarked with the outcomes of Monte Carlo
simulations of specific scintillation detectors. An accuracy at the level of
few percent is achieved. The case of a real liquid argon based detector is
explicitly treated and the predicted light yield is compared with the measured
value.
