Numerical Simulation of Optical Turbulence Utilizing Two-Dimensional Gaussian Phase Screens

Propagation of electromagnetic energy through the atmosphere is difficult task because of temperature fluctuations and index of refraction inhomogeneities which degrade the beams coherence. Understanding this phenomena is of practical importance for optical systems. This thesis presents an analytical numerical technique which simulates the effects of atmospheric turbulence. The extended Huygens-Fresnel principle was used to simulate wave propagation in a two-dimensional randomly varying medium, which is represented by thin, filtered, Gaussian phase screens. The wave optics code implements both Fresnel and Fraunhofer propagation, by employing the fast Fourier transform FFT algorithm. The analytical spatial coherence length, rho sub 0, and normalized intensity variance, sigma-sqI-sq, of the perturbed electric field, were examined. Results support the concept of intensity saturation for weak scattering cases, however, differences in the values of the theoretical and analytical spatial coherence lengths, occurred. Keywords Atmospheric optical turbulence Coherence length Mutual coherence function Saturation Huygens Fresnel principle Theses.