Abstract

Two Air Force Special Weapons Center NC-135 jet aircraft, one carrying a laser transmitter and the other a receiver, were used in an airborne laser-beam scintillation experiment in order to measure high-altitude values of the index-of-refraction structure parameter, C_n². Measurements were made at a wavelength of 0.6328 μm. Transmitter–receiver spacings of 0.5, 1.0, 1.5, 2.0, and 3.0 km were used. Altitude values ranged from 1.5 to 10.5 km in approximately 1.5-km steps. Computed log-irradiance scintillation parameters included probability distribution function, cumulative probability, variance, and temporal power-spectral density. Irradiance fluctuations were typically log-normal and temporal power spectra agreed reasonably well with theory. Measured values of C_n² were consistently larger than expected at high altitudes. Some contribution to the measured values of C_n² may have come from boundary-layer turbulence near the transmitting aircraft. However, this contribution was small. On the average, the upper atmosphere is more turbulent than current models predicted it to be.

© 1973 Optical Society of America

Measurements of Laser-Beam Scintillation in the Atmosphere

D. L. Fried, G. E. Mevers, and M. P. Keister
J. Opt. Soc. Am. 57(6) 787-797 (1967)

Experimental effects of finite transmitter apertures on scintillations*

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Scintillation and transmitter-aperture averaging over vertical paths*

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Scintillation measurements for large integrated-path turbulence*

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Analysis of Multiwavelength Observations of Optical Scintillation

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