Accession Number : AD0681352

Title :   SATURATION OF SCINTILLATION MAGNITUDE IN NEAR-EARTH OPTICAL PROPAGATION.

Descriptive Note : Memorandum rept.,

Corporate Author : BALLISTIC RESEARCH LABS ABERDEEN PROVING GROUND MD

Personal Author(s) : Deltz,Paul H. ; Wright,Neal J.

Report Date : OCT 1968

Pagination or Media Count : 44

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)

Descriptors :   (*LASERS, LIGHT TRANSMISSION), (*LIGHT TRANSMISSION, *ATMOSPHERIC MOTION), SCINTILLATION, PHOTOGRAPHS, RANGE(DISTANCE), TEMPERATURE INVERSION, ATMOSPHERE MODELS, HELIUM, NEON, SYMPOSIA

Subject Categories : Lasers and Masers
      Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE