3D ray tracing methods across inhomogeneous refractive indices using a transmission equation

Abstract

When an aircraft flies at high speed in a dense atmosphere, the airflow outside the optical window interacts to form a complex flow field structure with irregular and nonuniform refractive index distribution, which makes it difficult to accurately calculate the ray propagation path based on the refractive index field. To solve this challenge, three ray tracing implementation methods with fourth-order accuracy are proposed. By comparing with the spiral ray resolution results, it is found that the Adams method has the smallest computational error of 1.2 × 10 − 11 compared with the fourth-order Runge–Kutta method and the Richardson extrapolation method. The Adams method is the most computationally efficient in terms of computational time cost, followed by the Richardson extrapolation method, and finally the fourth-order Runge–Kutta method. The results show that the Adams method is the fastest and most accurate for different step sizes and grid volumes.