Bridging statistical scattering and aberration theory: ray deflection function-II: numerical validation

This paper presents a comprehensive experimental validation of a recently developed ray deflection function (RDF) approach, which offers a new framework, to our knowledge, for modeling surface roughness effects in optical systems. Through detailed geometrical ray-tracing simulations, we demonstrate that the RDF methodology successfully bridges two traditionally separate domains: statistical scattering models and deterministic aberration analysis. We implement and compare the two approaches for modeling a parabolic mirror with surface imperfections in three cases: (1) an ideal parabolic mirror baseline, (2) the conventional Harvey-Shack (HS) statistical scattering theory applied to ray perturbations, and (3) the newly proposed aberration term method based on the RDF theory. Our results confirm the statistical equivalence between the HS approach and the RDF-based aberration term method, with both producing close near-focal-plane distributions and focal volume characteristics. By establishing this equivalence, we validate that surface roughness effects can be accurately represented as deterministic aberration terms while maintaining fidelity to established statistical scattering models. The method translates a frequency-domain roughness specification (PSD over bands) into pupil-aberration statistics and system image-quality metrics, enabling direct conversion between BSDF-style surface specs and aberration budgets.