A ray–Gaussian beamlet hybrid model for simulating light propagation in inhomogeneous refractive media

Accurate modeling of light propagation through inhomogeneous refractive index media is essential in various optical diagnostics and imaging applications, including flow field interferometry, schlieren imaging, and atmospheric transmission. Traditional methods, such as pure ray tracing or full-wave optical simulations, are often limited by either insufficient physical representation or high computational cost. To address these limitations, this paper presents a hybrid physical model: Ray-Gaussian Beamlet Hybrid Model (RGHM). The incident light field is discretized into a bundle of rays, each undergoing ray tracing to account for refractive deflection caused by inhomogeneous media. The contribution of each ray to the optical wavefront is then evaluated using an off-axis Gaussian beamlet model. The superposition of all beamlets reconstructs the full complex wavefront at the imaging plane. Validation is carried out through numerical simulations involving a cylindrical region and CFD-derived flow fields. Results show that the accuracy of the method depends on the overlap factor P=W/D (beam waist over beam gap). Optimal accuracy is achieved when P ≥ 1 , while smaller values lead to artificial high-frequency structures. Across all tested cases, the proposed method yields amplitude and phase deviations within 10 − 3 of the reference, demonstrating particularly high fidelity in phase reconstruction. The model also effectively captures ray deflection effects in regions with steep refractive index gradients, offering a practical and precise solution for optical simulation in complex optical environments. • A hybrid ray-optics and wave-optics model is proposed for simulating transmitted wavefronts. • The model captures both beam deflection and diffraction in non-uniform refractive index fields. • The method ensures high accuracy and stability in both synthetic and CFD-based refractive fields.