The experiment of a system for measurements of the refractive index structure constant along a 1 km free-space laser propagation path

This paper presents experimental measurements of scintillation and to obtain optical turbulence information along a near-horizontal 1km free-space laser propagation path. Calculated values for the refractive index structure constant C_n² for several cases of different weather from September to December in the year of 2009. In this experiment, the measurement over a 10min period at a sampling rate of 0.01Hz was carried out, and the scintillation fluctuation experimental data was achieved. the C_n² was analyzed according to different weather such as sun, fog and snow and then we use different size of aperture to analysis the effect of aperture - averaging in week turbulence conditions. As a result, we found that the bigger receiving aperture the smaller scintillation variance and the value of C_n² is different according in different weather; the results of the experiment are in good agreement with the theory which was the reference for the design of the optical communication system.