Abstract
This paper reports the beam wave fl uctuations caused by strong atmospheric turbulence. These beam
wave fl uctuations are estimated by numerical calculations carried out using moment equation analysis
with thin phase screen approximation. The scintillation index for a plane wave is calculated as a
function of a parameter concerning the intensity of atmospheric turbulence, and the result is in good
agreement with previous studies. Transmission of the beam radius dependence of a scintillation index is
calculated using the first and second moments of wave intensity. The largest scintillation index is
obtained when the beam radius size equals (λ z/2π )1/2. The scintillation index of a beam wave is also
evaluated using the Rytov approximation method, which is based on perturbation analysis.
