Backscattering and polarization ratio for cylindrical graphite fibers at CO(2) laser wavelengths

Measurements are presented of backscattering from an artificial cloud composed of cylindrical graphite fibers at a distance of 730 m with a CO(2) lidar system at 20 wavelengths and two incident polarizations (horizontal and vertical). The backscatter measurements and the polarization ratio are in good agreement with single-scattering calculations for an infinitely long cylinder at normal incidence. The measurements give experimental evidence of the predominant orientation of graphite fibers with their long axes in a random position in the x-y plane (i.e., parallel to the ground).