Experimental Measurements Of Turbulence Induced Beam Spread And Wander At 1.06, 3.8, And 10.6 Ã‚Âµm

D. M. Cordray; S. K. Searles; S. T. Hanley; J. A. Dowling; C. O. Gott

doi:10.1117/12.932741

30 December 1981 Experimental Measurements Of Turbulence Induced Beam Spread And Wander At 1.06, 3.8, And 10.6 μm

D. M. Cordray, S. K. Searles, S. T. Hanley, J. A. Dowling, C. O. Gott

Proceedings Volume 0305, Atmospheric Effects on Electro-Optical, Infrared, and Millimeter Wave Systems Performance; (1981) https://doi.org/10.1117/12.932741
Event: 25th Annual Technical Symposium, 1981, San Diego, United States

Abstract

Lasers can be used for a number of applications involving atmospheric propagation. In these applications it is of interest to know the maximum range at which the laser beam can propagate without significant degradation due to atmospheric turbulence. The purpose of the measurements was to determine laser beam spread and wander as a function of the infrared wavelength, the optical turbulence level, and the propagation distance. Experiments were performed at White Sands Missile Range under conditions of low over-land turbulence levels, using 1.06μm, 3.8007μm, and 10.591μm lasers at ranges of 2, 6.4, and 10.5 km. The tests were conducted under a range of turbulence conditions, with C_N² most frequently of the order of 10-15 m-2/3. The NRL Infrared Mobile Optical Radiation Laboratory (IMORL) was used to generate the nearly diffraction limited beams produced by the lasers, to magnify the beam to a 90 cm diameter and to focus the beams onto a 120 cm collector. The intensity distribution at the collector mirror was recorded by a scanning infrared camera which dissects the image into 810 elements. The intensity distributions were recorded at a scan rate of up to 500 frames per second. Two dimensional scanning at the high scan rates provided excellent spatial and temporal resolution of the turbulence-degraded focal spot distributions. The data has been partially reduced and shows that 1.06μm is severly spread and broken up, that 3.8μm is slightly spread, and that 10.6μm shows little spread relative to its diffraction limited spot size.

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D. M. Cordray, S. K. Searles, S. T. Hanley, J. A. Dowling, and C. O. Gott "Experimental Measurements Of Turbulence Induced Beam Spread And Wander At 1.06, 3.8, And 10.6 μm", Proc. SPIE 0305, Atmospheric Effects on Electro-Optical, Infrared, and Millimeter Wave Systems Performance, (30 December 1981); https://doi.org/10.1117/12.932741

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