CALCULATION OF LIGHT FIELDS USING THE MODIFIED 2P(0) APPROXIMATION INTHE FRAMEWORK OF THE METHOD OF SEPARATION OF LIGHT-FLUXES

In this paper, we consider the problem of propagation of optical radia tion under conditions of flat geometry of the scattering medium. An or iginal approach to the calculation of light fields based on the method of separation of fluxes with subsequent expansion of descending and a scending radiation in the modified Legendre polynomials is suggested. Of principal importance is the separation of the anisotropic part of r adiation in the descending flux, which corresponds to photons that sys tematically propagate toward the inside of the medium. In the framewor k of the modified 2P(0) approximation for the light fluxes, the set of equations is formulated. It is shown that the value of the mean singl e-scattering angle is the major characteristic of a medium directly co nnected with the probability of a change in the sign of the photon vel ocity projection on an arbitrary direction. The Green's function of th e set of equations in the modified 2P(0) approximation for a flat scat terer of finite thickness is determined. In a particular case of isotr opic single scattering, the expression for the reflection coefficient from a semi-infinite medium is obtained. Comparison of obtained result s with the results of calculations in the two-flux approximation and w ith the exact results of Ambartsumyan and Chandrasekhar is presented.