Recent developments in the micro- and nanotechnologies indicate an ongoing trend of requests for surfaces that cover several different functionalities at once. Such so-called multifunctional surfaces combine, for example, extreme wetting behavior (e.g. superhydrophobicity) with excellent optical properties (e.g. reduced light scattering) or high mechanical robustness. This requires a comprehensive understanding of the individual properties (topography, roughness, wetting, …) and their relationships. Therefore, an adequate technical realization of such multifunctionality is only possible through tailored surface roughness characteristics. For instance, surface roughness and high optical quality are competing properties, because roughness required for functionalities (e.g. wetting), also leads to increased scatter losses. Defining and controlling the roughness within the entire range of the application-relevant surface spatial frequencies is hence a crucial factor for a successful development of such surfaces. This can be achieved by combining different metrology approaches such as atomic force microscopy, white light interferometry, and light scattering methods, which can also be exploited to characterize additional surface properties such as homogeneity and defects.
In this talk we will discuss various applications of multifunctional surfaces and provide an overview of our methodology to model, predict, and control such surfaces.