A method based on 3D ray tracing for aero optical wavefront analysis

Abstract

Considering missiles mounted with infrared detection system flying at hypersonic speed, infrared radiation (IR) from the target will suffer light deflection and wavefront distortions when passing through the flowfields surrounding irdome, namely aero-optical effect. The accuracy of detection and identification probability for missile's IR detectors will be obviously cut down. This paper presents a method based on 3D ray tracing for studying the aero optical light transmission effect existing on the surface of hemispheric irdome. Density distribution surrounding irdome is calculated utilizing Reynolds Averaged Navier–Stokes method and k-epsilon turbulence model. Gladstone–Dale formula is used to establish the relationship between density and refractive index. Generalized regression neural network and Barron operator are used for interpolating refractive index and its gradient respectively so as to obtain the refractive index distribution. Three-dimensional (3D) ray tracing algorithm is derived based on Snell's Law, which can effectively calculate the optical path difference, Strehl ratio and other parameters under different flight altitudes, speeds and angle of attacks.