The quality of laser beam in free – space optical communication is affective by the
atmospheric turbulence, this quality of beam is describing by two important parameters
signal –to- nose ratio (SNR) and bit error rate (BER) .In this paper using Laboratory
simulation turbulence cell to analyzing the effective atmospheric turbulence on beam
winder and Beam fluctuating power in different turbulence conditions, also effective at
same conditions on BER and SNR