Development of an Optical Turbulence Model for Use in Ray Tracing Simulations

Optical turbulence is an atmospheric effect that induces distortions and aberrations in an imaging system. In this study, we reviewed methods for estimating the turbulence strength parameter Cn² along with various methods for simulating the resulting image distortions, focusing on Zernike-based and angle-of-arrival statistical approaches. We developed a prototype ray-tracing simulator that combines intermodally correlated Zernike modes with angle-of-arrival statistics to model image distortion. We compared our results to images captured under varying levels of turbulence and identical system parameters. The results provide a solid first step toward implementing a physically and empirically based method for including image distortion effects in high-fidelity ray tracing simulators.

At this stage, we performed a qualitative evaluation of our simulator. We generated images for four degrees of turbulence, evenly spaced from the minimum to the maximum values captured in the reference dataset. Upon visual inspection of the results, we concluded that the general amount of blur and uniform distortion was comparable to the truth data. General trends and magnitude of aberration appeared to track with increasing turbulence values. The more subtle effects of scintillation along the edges were not captured in the simulated images. This study revealed some possible paths toward modeling atmospheric turbulence in more sophisticated radiative transfer models, such as DIRSIG.

Turbulence Dataset on Github