EFFECTS OF ATMOSPHERIC-TURBULENCE ON THE VISIBILITY AND SPACING OF INTERFERENCE-FRINGES

Within the framework of a feasibility study of remote cross-wind velocity measurements by means of laser Doppler anemometry (LDA), an investigation was made of the atmospheric fluctuation effects on an optical interference fringe system generated over a distance of 500 m. Variations of the fringe visibility and spacing have been recorded simultaneously. In order to characterize the optical turbulence of the atmosphere during the measurements, an optical scintillometer was used. Provided the atmospheric extinction is low enough, the measured results show that, even under weather conditions which are very unfavorable to the propagation of laser beams, the interference fringe pattern generated is of sufficient quality for LDA measurements.