Depolarization of a Laser Beam at 6328 A due to Atmospheric Transmission

The depolarization of a linearly polarized laser beam was investigated primarily with an optical path of 4.5 km. A He-Ne gas laser at 6328 A was used with an additional polarizer at the output and with a rotating polarization filter assembly in front of the receiver. Values of depolarization found ranged between 10(-7) rad and about 5 x 10(-5) rad. The lower limit was determined by the quality of the polarizer-analyzer combination used. These experimental values of depolarization are very much higher than that predicted by theories regarding turbulence-induced depolarization.