The method of small perturbations is used to calculate the degree of coherence of a gaussian beam in a random medium. The refractive-index fluctuations of the medium are assumed to be small and statistically homogeneous and isotropic. Based on the Kolmogorov spectrum, asymptotic and numerical solutions are obtained for a collimated beam and a focused beam propagating in a turbulent atmosphere. For both the collimated beam and the focused beam, the degree of coherence increases as the value of L/ka2 increases, other parameters being fixed; a is the beam radius. Furthermore, the solution for an infinite plane wave forms the lower bound of the degree of coherence for a collimated beam, and the solution for a spherical wave forms the upper bound for both the collimated beam and the focused beam. These results are explained physically.
© 1970 Optical Society of AmericaFull Article | PDF Article
OSA Recommended Articles
T. L. Ho
J. Opt. Soc. Am. 59(4) 385-390 (1969)
E. Collett and R. Alferness
J. Opt. Soc. Am. 62(4) 529-533 (1972)
J. Opt. Soc. Am. 60(4) 518-521 (1970)