Statistical properties of optical turbulence in a convective tank: experimental results

The Fried coherence length is quantitatively measured by means of two different methods in a convective turbulence tank for wavefront compensation experiments in adaptive optics. The spectra of angle-of-arrival (AA) fluctuations and their probability distribution are given. The fluctuation of the wavefront phase follows a normal distribution. The chi (2) distribution appears to be a reasonable assumption for variance of AA fluctuations, and the statistical distribution P(r(o)) regarding the Fried coherent length ro of experimental results is shown. The spectrum of AA fluctuations in the x-direction, being the same as the spectrum in the y-direction, obviously indicates that the turbulence in the tank is an isotropic feature. The experimental results for the Fried coherence length and temperature differences between a heated plate and cooled plate correspond to the similarity relationship in fluid mechanics and thermodynamics experiments in a convective turbulence tank.