Measurements of partially spatially coherent laser beam intensity fluctuations propagating through a hot-air turbulence emulator and comparison with both terrestrial and maritime environments

Measurements of partially spatially coherent infra-red laser beam intensity fluctuations propagating through a hot-air turbulence emulator are compared with visible laser beam intensity fluctuations in the maritime and IR laser beam intensity fluctuations in the terrestrial environment at the United States Naval Academy. The emulator used in the laboratory for the comparison is capable of generating controlled optical clear air turbulence ranging from weak to strong scintillation. Control of the degree of spatial coherence of the propagating laser beam was accomplished using both infrared and visible spatial light modulators. Specific statistical analysis compares the probability density and temporal autocovariance functions, and fade statistics of the propagating laser beam between the in-laboratory emulation and the maritime field experiment. Additionally, the scintillation index across varying degrees of spatial coherence is compared for both the maritime and terrestrial field experiments as well as the in-laboratory emulation. The possibility of a scintillation index ‘sweet’ spot is explored.