Results from comparative measurements of turbulence and transmission at laser wavelengths in the shortwave infrared (SWIR) and longwave infrared (LWIR) wavelength bands are presented. The experimental setup uses a dual band transmitter with coaxially aligned laser beams and a receiver based on a common collecting off-axis parabolic mirror to direct the radiation to the detectors. Measurement of turbulence was performed on one occasion and transmission was measured in two events with fog and one event with falling snow. The turbulence data is compared to optical wave simulations, and the transmission data is compared to Mie calculations based on aerosol and hydrometeor data. As expected, the received power scintillations caused by atmospheric turbulence are stronger in the SWIR band compared to the LWIR band. The measured transmission in fog and snow can be explained by the measured characteristics of the scattering medium. In fog, depending on the particle size distribution, higher transmission can be observed in either wavelength bands. In snow, on the other hand, it is shown that the transmission is higher in the SWIR band as an effect of forward scattering.
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