In 1975, we reviewed the recent developments on wave propagation in turbulent media. In this paper, we update that paper to include recent results on adaptive optics, intensity scintillations, pulse propagation, atmospheric measurements at visible, IR, and millimeter wave frequencies, speckle interferometry, and other related topics.

Electromagnetic beam propagation in turbulent media: An update

It has been shown theoretically and experimentally that, in the case of extended ground paths under conditions of strong intensity fluctuations when the atmospheric-turbulence-structure parameter is determined based on the half-width of the mean diffraction picture in the lens focal plane, one should take into account the beam-diffraction parameters and laser-source spatial coherence.

Measurements of atmospheric-turbulence-structure parameter using a space-limited laser beam.

The Kolmogorov hypothesis of an inertial range within the spectrum of steady state turbulence is used to show that the space-time structure function for the velocity fluctuations in a fluid has the form of (r/sup /sup 4///sub 3// + epsilon/sup /sup 2///sub 3// t/sup 2/)/sup /sup 1///sub 2// where r and t are the space and time lags and epsilon the energy, for a reference frame in which the mean velocity is zero. The associated space-time spectra are also derived. Equations for the propagation of the N event space-time correlation functions of the complex electric field are derived assuming that the width of the angular spectrum of plane waves is much less than a radian.

Space-time analysis of wave propagation through a turbulent medium

The unique property of the theoretical formula for the angular spectrum of a point source seen through a turbulent medium is that it is related in simple closed form to the integrated structure function of the turbulence. It therefore provides a reliable measure of the state of turbulence. Rudimentary measurements over a 5 km path show a remarkable confirmation, over a range 1000:1 in intensity, of the Kolmogoroff two-thirds law, and of the underlying theory of wave propagation through a turbulent medium.

V. H. Rumsey

Papers

Angular spectrum measurements of atmospheric turbulence