Accession Number : AD0759804

Title :   Short-Term Average Optical Beam Spread in a Turbulent Medium.

Descriptive Note : Research rept. Aug-Sep 72,

Corporate Author : AEROSPACE CORP EL SEGUNDO CALIF LAB OPERATIONS

Personal Author(s) : Yura,Hal T.

Report Date : 15 DEC 1972

Pagination or Media Count : 29

Abstract : On the basis of the extended Huygens-Fresnel principle, a general expression is derived for the short-term average optical beam spread, as measured with respect to the instantaneous center of energy of the beam, of an initially coherent optical beam wave propagating in a weakly inhomogeneous medium. The present analysis applies to the near field of the effective coherent transmitting aperture, where the beam wanders (dances) as a whole and does not break up into multiple patches or blobs. Central to the analysis is the short-term average mutual coherence function (MCF) of a spherical wave. This quantity is obtained from the corresponding long-term MCF by removing the random tilt of the wave front. Analytic expressions for the short-term beam spread are presented for the case of a Kolmogorov spectrum and the short-term average MCF derived by Fried. (Author Modified Abstract)

Descriptors :   (*COHERENT RADIATION, ATMOSPHERIC MOTION), LIGHT TRANSMISSION, FOCUSING, REFRACTIVE INDEX, TURBULENCE

Subject Categories : Atmospheric Physics
      Lasers and Masers

Distribution Statement : APPROVED FOR PUBLIC RELEASE