Optical propagation in laboratory-generated turbulence.

A versatile and useful facility for simulating the effects of atmospheric turbulence on optical propagation is described, and the relevant system parameters are characterized. The scattering medium is a turbulent liquid (ethanol) with the turbulence created by unstable convection generated by a strong vertical thermal gradient. Measurements of the structure function and the spatial spectrum of the resulting refractive index fluctuations are presented and compared with the theoretically predicted forms. The effects of this scattering medium on laser beam propagation are determined and compared to the first-order Rytov theory. In particular, probability density functions, moments, and spatial covariance functions of the irradiance resulting from propagation through the system with a variety of turbulence levels and path lengths are presented.