Abstract
Results are presented from an experimental study of the effects of wavelength, range, and thermal turbulence intensity on the laser scintillation magnitude, represented by the log-intensity standard deviation, σ. During the first phase of the study, intensity fluctuations at 0.6328 μm were measured over a near-ground horizontal path for six ranges out to 7.6 km. Similar measurements were made during the second phase at four ranges out to 2.5 km for three wavelengths: 0.4880 μm, 0.6328 μm, and 1.064 μm. A 5-mm diam receiver aperture was used in all cases. During both phases, concurrent measurements of the refractive-index-structure function Cn were obtained. It was observed that the measured scintillation (σm) at 0.6328 μm reached a mean maximum of 1.05 when the theoretical Tatarski value (σt) was 2.5 and then decreased at larger σt to a value about 0.5, where the scintillation showed evidence of leveling off. The mean maximum scintillation at 0.4880 μm is 1.09, and at 1.064 μm it is 0.82; the ratios of the maxima are well approximated by the minus seven-twelfths power of the wavelength. At large σt values, the scintillation depends only slightly on wavelength.
© 1973 Optical Society of America
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