Analysing the Influence of Source Spectrum on the Optical Measurements of Turbulence
The effect of the source spectrum on the measurement accuracy of optical wave arrival angles and the calculation of the path-averaged structure parameter of refractive index fluctuations are discussed. The wavelength dependence of the variance of wave arrival angle fluctuations is investigated for two reasons. The first is related to the fact that in the approximation of smooth perturbations, phases are dependent on a wavelength. The second explanation has to do with the refractive index’s wavelength dependency and, as a result, its fluctuations. Based on smooth perturbation approximation, all methods based on scintillations of optical wave measurements allow one to work only with restricted weak intensity fluctuation. The effect of the source continuum on the measurement accuracy of the variance of arrival angle fluctuations and, indirectly, on the estimation accuracy of the path-averaged refractive index structure parameter is taken into account using strict equations. The effect of the source spectral composition can be ignored for most radiation sources (even nonmonochromatic ones).
Author (s) Details
Vladimir P. Lukin
V.E. Zuev Institute of Atmospheric Optics, Siberian Branch of the Russian Academy of Sciences, Tomsk, Tomsk State University, Tomsk, Russia.
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