SATURATION OF SCINTILLATION MAGNITUDE IN NEAR-EARTH OPTICAL PROPAGATION.
Abstract
Both a pulsed laser and a helium-neon laser have been used as optical sources to examine the magnitude of scintillation as a function of range and strength of turbulence over a near-earth, horizontal path. A photo-optical technique was utilized to record directly a 61-cm cross section of a received laser beam. Photographs of beam cross sections made at ranges of from 200 to 1500 m were used to compute log-intensity variances. Simultaneous with the optical data, measurements of the index structure coefficient Cn were made through a high-speed thermal technique. The data are used to test the spherical wave equation giving the log-amplitude variance as a function of range and Cn. The measurements indicate that the variance increases for ranges up to about 700 m, at which distance saturation occurs. The data are also compared with the saturation equations of Tatarski and deWolf. In addition, the effect of the transmitter beam divergence on the magnitude of scintillation is examined. Finally, a modification of the inertial subrange of the Kolmogorov turbulence model is suggested to explain the occurrence of particular optical effects observed during temperature inversion conditions. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1968
- Accession Number
- AD0681352
Entities
People
- Neal J. Wright
- Paul H. Deltz
Organizations
- Ballistic Research Laboratory