Development of an optical turbulence model based on eddy length scale and refractive index statistics

Atmospheric transmission of optics is significantly affected by fluctuations in the index of refraction. The spatiotemporal changes in the refractive index lead to power surges and fades, spatial incoherence, and beam wander, among other deleterious effects. Usually, modeling these effects on transmission and imaging assumes thin turbulence regions and isotropic turbulence. We develop an alternative model based on a spherical bubble packing scheme with discrete volumes of turbulent eddies of different sizes. Using Snell’s laws and ray tracing, optical transmission is calculated. The distribution of bubble sizes and refractive index spectrum are accounted for based on statistics in the atmospheric boundary layer. Statistics of the length scale distribution are based on power law assumptions from a linear-eddy model. The refractive index spectra are obtained from isotropic models, such as the von Karman spectrum, and the uniform shear turbulence model with buoyancy effects. The spherical optical turbulence bubble model is validated by the spectra obtained from atmospheric and scintillation measurements as well as imaging in the atmospheric surface layers and compared with phase screens.