The experimental dependences of the duration of pulses and the angular structure of radiation in an optically thick scattering medium (τ=10 to 70) are found to be essentially different from the results obtained using the diffusion approximations. Based on empirical data, a technique is proposed for describing the shape of the pulse polarization components using the formulas of the small-angle diffusion approximation, using the effective diffusion coefficient which increases as the photon dwell time in the medium is increased. The applicability limits of the asymptotic solutions are estimated.