Accession Number : ADP000331

Title :   Degradation of a Laser Beam by a Turbulent Jet,

Corporate Author : AIR FORCE FLIGHT DYNAMICS LAB WRIGHT-PATTERSON AFB OH

Personal Author(s) : Cudahy,G. F. ; Van Kuren,J. T. ; Wright,H. E.

Report Date : JUN 1982

Pagination or Media Count : 23

Abstract : A laser beam traversing turbulence undergoes an intensity reduction which is correlated with the statistical behavior of refractive index perturbations. The analytical relation predicts degradation as a function of beam diameter, path length, wave number and wave structure function. Refractive index perturbations are approximated via the equations of state using temperature and velocity perturbations. An experiment was conducted in which visible wavelength lasers traversed a well documented two-dimensional jet. Temperature perturbations vary from 0.25 to 1.89 K and velocity fluctuations range from 9.2 to 30.8 m/sec. Measured central spot intensities are as low as 18% of the undisturbed beam, depending on jet Mach number, beam position relative to the jet exit and wavelength. The average difference between theory and experiment is two percent in terms of far field intensity. (Author)

Descriptors :   *Laser beams, *Degradation, *Turbulent flow, Perturbations, Refractive index, Intensity, Temperature, Diameters, Reduction, Equations of state, Beam steering, Field intensity, Far field, Visible spectra, Wave functions, Optics, Wave propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE