A Technique for Estimating the Inner Scale and Strength of Turbulence along an Optical Propagation Path

The Kolmogorov spectrum for the refractive index is often assumed for analysis and simulation of optical propagation through turbulence. It is recognized that the Hill spectrum, including inner scale, is a more realistic model of index variations. This model includes a turbulence enhancement in a spectral subrange prior to the inner scale roll-off. Knowledge of this enhancement and the subsequent roll-off is important for predicting the statistics of both phase and scintillation effects. A technique for estimating the inner scale, L0, is proposed which can be implemented as part of a simple sensor system. The proposed inner scale sensor is also capable of estimating the Fried coherence length, r0, and the Greenwood frequency.