Scintillation analysis of LIDAR systems operating in weak-to-strong non-Kolmogorov turbulence: Unresolved target case

We use a non-Kolmogorov power spectrum for theoretical investigation of laser beam propagation in the double-passage problem: transmitter-target-receiver. The major application of our work is the light detection and ranging (LIDAR) system operating in the zone of the atmosphere where non-Kolmogorov turbulence may be present. We show that the scintillation index is substantially affected by non-Kolmogorov turbulent channels at any turbulence strength. We consider the case of a small unresolved target and our analysis is valid for both the bistatic and monostatic configuration of the LIDAR system, in which the latter leads to the enhanced backscattering effects. Additionally, the paper contains a discussion of the simulation approach to light propagation through non-Kolmogorov turbulence. The simulation results and a discussion of their agreement with the theory are included. We found that the theory and the results of the simulations agree only to a certain extent. The ""giant spikes"" that occur when propagating through ""deep turbulence"" are responsible for the lack of better agreement. Their influence on the scintillation index and also on the probability density function of intensity probably requires a theoretical approach.