We show comparisons between calculations and measurements of angle-resolved light scattering distributions from clear dielectric, isotropic coatings. The calculated distributions are derived from topography measurements performed with scanning white light interferometric microscopes. Kirchhoff formalism for light scattering is applied to the topographic images to derive the calculated scattering distributions. The measured distributions are obtained with the spectral tri-function automated reference reflectometer (STARR) developed by NIST having a detector with aperture half-angle of about 1.4 degrees and an instrument signature with similar angular width, both of which are modeled in the calculations. Comparisons between the measured and calculated results are shown for two surfaces with rms roughness of approximately 150 nm and 750 nm. This work is part of a project designed to advance appearance metrology through a systems approach. We are applying techniques in optical metrology, surface metrology, mathematical modeling, and computer rendering to the development of new methods of appearance characterization and image rendering of surfaces. Experimental and modeling research activities will be conducted in four areas: coating composition, microstructure of surfaces, reflectance properties, and appearance descriptions. The overall goal of this work is to support the capabilities for researchers and engineers to assess the effects of surface constituents on appearance properties and to design surfaces with appropriate appearance and durability properties.
Citation: Inter-Society of Color Council News
Issue: No. 379
Pub Type: Journals
appearance, appearance metrology, coatings, computer rendering, light scattering, mathematical modeling, optical metrology, STARR, topography measurements