The Shuttle Landing Facility runway at the Kennedy Space Center in Cape Canaveral, Florida is almost 5 km long and 100 m wide. Its homogeneous environment makes it a unique and ideal place for testing and evaluating EO systems. An experiment, with the goal of characterizing atmospheric parameters on the runway, was conducted in June 2005. Weather data was collected and the refractive index structure parameter was measured with a commercial scintillometer. The inner scale of turbulence was inferred from wind speed measurements and surface roughness. Values of the crosswind speed obtained from the scintillometer were compared with wind measurements taken by a weather station.
Scintillation is one of the most common statistics in the literature of mathematical modeling of laser propagation through random media. One approach to estimating scintillation is through the Rytov approximation, which is limited to weak atmospheric turbulence with the standard Kolmogorov spectrum. Recently, a modification to the Rytov approximation was developed. Through a filter function approach, the new results for scintillation are valid for moderate to strong fluctuations along a horizontal path. To date, expressions governing scintillation for plane, spherical, and Gaussian beam waves has been developed for horizontal propagation paths. For the special cases of plane and spherical waves, expressions have been developed for slant paths. In this paper, an expression governing scintillation of a Gaussian beam along an uplink slant path valid in all regimes of turbulence is presented.
Recently, a heuristic model for scintillation in moderate to strong turbulence was developed. It is based on the idea of filter functions that eliminate scale sizes that lose their ability to affect a laser beam as it propagates. This approach allows the validity of the Rytov approximation to be extended into moderate to strong turbulence. In this paper, we investigate applying this theory to second order statistics.
Recently, new theory governing laser beam scintillation was developed for all regimes of optical turbulence. This theory is based on the Rytov approximation but modified with a filter function that eliminates intermediate scale sizes that do not contribute to the refractive and diffractive effects of propagation. This modification extends the validity of the Rytov approximation into moderate to strong regimes as evidenced by the agreement with simulations and experimental data. In this paper we apply this theory to the phase covariance and new expressions governing phase fluctuations are presented. The phase structure function is then compared with previous experimental data.