Interpreting the radiative properties of advanced high strength steel using the geometric optics ray-tracing approximation

This study investigates the relationship between surface topography and radiative properties of advanced high strength steel (AHSS) alloys using the geometric optics approximation (GOA) with ray tracing. Five AHSS coupons with different alloy compositions and surface topographies are investigated. The directional-hemispherical and specular reflectance of samples are measured using a UV-Vis-NIR spectrophotometer (0.25-2.5 mu m) and two FTIR spectrometers (2.5-20 mu m), while surface profiles used in the ray tracing model are obtained using an optical profilometer. Predictions of directional-hemispherical reflectance are consistent with the experimental data when the surface parameters and incident wavelengths are within the valid GOA domain. Reflectance predictions in the specular direction are also in line with the measurements when the roughness parameters are in the specular approximation domain. (C) 2021 Elsevier Ltd. All rights reserved.