Wave Optics Simulator for Lasers in Time-Evolving Turbulence

Atmospheric optical turbulence can be characterized as refractive index variations along a beam's propagation path due to local fluctuations in temperature and humidity. Turbulence randomly perturbs the wavefront of a beam traveling through the medium, leading to effects such as scintillation and beam wandering. Wave optics simulations use phase screens and Fourier techniques to accurately model phase change of light sources as they travel through turbulence. Georgia Tech Research Institute has enhanced the open-source wave optics toolbox known as WavePy to accurately simulate the propagation of a laser beam over a path length of time-evolving horizontal turbulence. The simulation tool incorporates an optimization routine designed to accept scenario parameters and return receiver and source plane sampling parameters that ensure accuracy and fidelity of the simulation output. This simulation tool is designed to minimize the potential for common faults of wave optics simulations, including: phase-wrapping of the atmospheric phase screens over time, energy loss of the beam over the propagation path, and aliasing of scintillation effects at the receiver plane. This simulator has applications towards informing the design of detectors that can accommodate the changing angle of divergence of the beam as it approaches the detector, which is an important consideration for systems such as laser beam rider missile guidance systems. Initial results towards modeling the effects of varying beam parameters and simulation conditions are presented and analyzed.