Characterization of the effects of the turbulence on the propagation of a laser beam in air

The measurements of long distances are strongly influenced by turbulence effects and by gradients of temperature. The topic of this paper is the description of the system developed at INRiM to investigate these effects. The system is composed of two different parts: the first system, devoted to the measurement of the phase fluctuation due to the turbulence, is a synthetic wavelength interferometer where the two arms are formed by two parallel beams at a variable distance in open air; the second system, to measure the beam wandering, is composed of a He Ne laser beam sent to a CCD camera and to a PSD (position sensitive detector). The first preliminary results obtained in laboratory conditions and in open air are described