MULTIWAVELENGTH LASER PROPAGATION STUDY. 2
Abstract
A comprehensive, multiwavelength laser-beam propagation facility was operated over a horizontal, 1 mile path in order to investigate the adequacy of the commonly-used atmospheric model and to establish the wavelength-dependence of scintillations. The optical measurements included log amplitude variances, covariances, scintillation spectra, probability distributions, and receiver and transmitter aperture effects. The microthermal measurements included turbulence spectra, critical scales, and temperature probability distributions. It was found that the inertial subrange model constitutes only an approximation to the true turbulence structure, and that the inner scale is often nonnegligible. The prevalence of quasi-discrete inhomogeneities in the refractive index structure constant was verified, and the consequent difficulty in relating nonoptical 'strength of turbulence' measurements to actual scintillations is pointed out. In spite of these inadequacies in the atmospheric model, it was found that the unsaturated multiwavelength scintillations compared reasonably well with theoretical predictions when based on the turbulence as determined from scintillations of a short-path, portable laser. Also, there was no indication of saturation of longer wavelengths at low variances relative to those for visible wavelengths. These are other tentative conclusions are discussed in detail.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1970
- Accession Number
- AD0709458
Entities
People
- J. R. Kerr
Organizations
- Oregon Health & Science University