
Accession Number : ADA291156
Title : Optimum Truncation of a Gaussian Beam for Propagation Through Atmospheric Turbulence.
Descriptive Note : Technical rept.,
Corporate Author : AEROSPACE CORP EL SEGUNDO CA TECHNOLOGY OPERATIONS
Personal Author(s) : Yura, H. T.
PDF Url : ADA291156
Report Date : 15 NOV 1994
Pagination or Media Count : 20
Abstract : We consider the mean onaxis farfield (or focalplane) irradiance of a Gaussian Beam truncated by a circular aperture in the presence of atmospheric turbulence. In the absence of turbulence, we present an accurate analytic approximation for the irradiance distribution that is valid within the main central lobe of the beam. Based on this approximation, we then obtain the mean onaxis farfield irradiance and corresponding turbulence Strehi ratio for the truncated Gaussian beam. By maximizing the onaxis irradiance, we obtain the optimum ratio of the beam diameter to the aperture diameter in the presence of turbulence and present results for the corresponding maximum onaxis irradiance as a function of the strength of turbulence. In particular, for D/r sub 0 > 1, where D is the aperture diameter, and r sub 0 is Fried's coherence length, optimum truncation of a Gaussian beam and uniform illumination of a circular aperture (where the same total power is uniformly distributed over the aperture) result in the same onaxis irradiance in the presence of uncompensated turbulence. (AN)
Descriptors : *LASER BEAMS, *OPTICAL ANALYSIS, MATHEMATICAL MODELS, PROPAGATION, OPTIMIZATION, COHERENCE, ACCURACY, TURBULENCE, ATMOSPHERIC DISTURBANCES, ATMOSPHERIC MOTION, ILLUMINATION, FAR FIELD, APPROXIMATION(MATHEMATICS), RADIANCE, FOCAL PLANES, APERTURES, FIELD INTENSITY.
Subject Categories : Lasers and Masers
Optics
Distribution Statement : APPROVED FOR PUBLIC RELEASE