Abstract

Results are presented from an experimental study of the effects of range, path geometry, and thermal turbulence intensity in the planetary boundary layer on the laser scintillation magnitude, represented by the log-intensity standard deviation σ. Intensity fluctuations of two 15-mW helium–neon laser beams propagating along reciprocal slant paths were measured simultaneously for a path elevation of 460 m and horizontal ranges from 0.6 km to 10 km, during both daytime and nighttime periods. Vertical profiles of the refractive-index-structure function C_n were obtained concurrently along with conventional wind and temperature profiles. It was observed that the range and turbulence dependence of σ differs significantly under inversion and lapse atmospheric conditions. When the scintillation predicted by the classical theory of Tatarski (σ_t) is used as a scale factor, the observed scintillation (σ_m) values occur at σ_t⁻-values that are about a factor of 2 larger for lapse conditions than for the inversion cases. This may reflect a dependence of the scintillation pattern on the frequency (or scale) of thermal turbulence fluctuations (represented by C_n), in addition to the well-known intensity dependence. The value of σ_m at saturation is slightly larger for the ground-to-air path (σ_m ≈ 1.7) than for the air-to-ground path (σ_m ≈ 1.4). Comparisons are made of the ratio of the sigma values along the two paths as a function of range and turbulence intensity; the observed ratios are poorly described by the existing theory.

© 1973 Optical Society of America

Analysis of Multiwavelength Observations of Optical Scintillation

Walter F. Dabberdt and Warren B. Johnson
Appl. Opt. 12(7) 1544-1548 (1973)

Airborne laser-beam scintillation measurements at high altitudes*

Glen J. Morris
J. Opt. Soc. Am. 63(3) 263-270 (1973)

Scintillation measurements for large integrated-path turbulence*

James R. Dunphy and J. Richard Kerr
J. Opt. Soc. Am. 63(8) 981-986 (1973)

Laser Beam Behavior on a Long High Path

James B. Mason and James D. Lindberg
Appl. Opt. 12(2) 187-190 (1973)

Scintillation and transmitter-aperture averaging over vertical paths*

P. J. Titterton
J. Opt. Soc. Am. 63(4) 439-444 (1973)