Laser setup for measuring ground-level turbulence

Ground-level turbulence is usually strong and can thus be a limiting factor for many applications such as laser communications or astronomical observations. In this paper, the working principle of a setup for characterization of optical turbulence along a horizontal path in the lower boundary layer is described. The system includes a telescope focusing a laser beam onto a retro-reflector located at a distance of 410 meters as well as an optical test-bench comprising two cameras and a Shack-Hartmann wavefront sensor. Some of the challenges encountered when using this type of sensor for measurement of strong turbulence are discussed. Furthermore, two techniques for estimation of Fried's coherence length r0 are presented and their results compared.