The optics and semiconductor industries make increasing use of innovative materials and complex nanostructures, whose optical properties are difficult to measure and often not accurately known. This project addresses the development of traceable metrology and advanced mathematical methods to characterize these materials for wavelength ranges from soft-X ray to IR. A database including optical constants with associated uncertainties for bulk materials and ultrathin-film systems and industrially relevant datasets will be set up. This tool is crucial for simulations and design of materials with tailored properties, enabling innovations by development of novel materials and devices in semiconductor industries and nanotechnologies.