Modeling of light scattering in different regimes of surface roughness

TLDR

Light scattering from rough metallic surfaces is commonly modeled using classical Rayleigh‑Rice vector perturbation theory or the newer Generalized Harvey‑Shack theory, whose validity, accuracy, and practicality are critically assessed. The study explores whether roughness parameters can be retrieved from measured scattering data across different roughness regimes. The authors model scattering from rough metal surfaces with nanometer‑scale roughness using both classical and generalized theories and compare the results to experimental measurements. Approximate scatter models are shown to be surprisingly accurate when benchmarked against Rigorous Coupled Wave Analysis for sinusoidal gratings and against experimental data at 325 nm, 532 nm, and 1064 nm for stochastically rough surfaces.

Abstract

The light scattering of rough metallic surfaces with roughness levels ranging from a few to several hundred nanometers is modeled and compared to experimental data. Different modeling approaches such as the classical Rayleigh-Rice vector perturbation theory and the new Generalized Harvey-Shack theory are used and critically assessed with respect to ranges of validity, accuracy, and practicability. Based on theoretical calculations and comparisons with Rigorous Coupled Wave Analysis for sinusoidal phase gratings, it is demonstrated that the approximate scatter models yield surprisingly accurate results and at the same time provide insight into light scattering phenomena. For stochastically rough metal surfaces, the predicted angles resolved scattering is compared to experimental results at 325 nm, 532 nm, and 1064 nm. In addition, the possibilities of retrieving roughness information from measured scattering data for different roughness regimes are discussed.