Boltzman-Langevin equation for laser beam propagation in turbulent atmosphere: scintillations for weak and moderate turbulence

摘要

The scintillation index is obtained for the practically important range ofweak and moderate atmospheric turbulence. To study this challenging range, theBoltzman-Langevin kinetic equation, describing light propagation, is derivedfrom first principles. The paraxial approximation for laser beams reduces thecollision integral for photon distribution function (PDF) to two-dimensionaloperator in the momentum space. Analytical solutions for the average value ofPDF as well as for its fluctuating constituent are obtained with the use ofiteration procedure. The calculated scintillation index is considerably greaterthan that obtained within the Rytov approximation even at moderate turbulencestrength. The relevant explanation is given.