Surface analysis, or surface metrology, is a vast field covering the analysis of textures and the measurement of features such as the waviness, roughness, and roundness of materials and objects. The aim of these studies is to understand how an object's origin and history (e.g. manufacture processes and wear) have influenced its texture and how this will affect its interactions with other components and materials. Accurate and reproducible measurements of differentiations and correlations in texture are vital as these give rise to such fundamental properties as adhesion, abrasion, friction and surface aesthetics.
Optimizing surface character can improve product performance in virtually every industry, but desired behaviour can vary greatly with intended application. In many industries, for example, a high degree of roughness is undesirable as it causes friction, wear and fatigue, which can ultimately lead to the premature breakdown of components. In other industries, a certain amount of roughness can be beneficial as it enables surfaces to trap lubricants more easily. Surface metrology is also used to support research in a variety of fields from the analysis of minerals in geology, to the development of novel medical devices, where the latest generation of implants are using new finishes to reduce the adhesion of bacteria and the development of detrimental biofilms.
In order to assess variances in surface texture, metrologists rely on a variety of microscopic techniques from simple brightfield analysis to differential interference contrast microscopy (DIC), interferometry and polarization analysis. Depending on the intended application of the material or object, the scale of interest can vary from the micron to the nanometer, but in every case the quality of the objectives is paramount. Accurate analysis of texture can reveal the crucial topographical characteristics that determine functional capabilities, limitations and the overall performance of products and devices.
Research laboratories at universities and materials manufacturers require ever higher levels of precision in surface measurements. In the case of silicon carbide (SiC), essential to next-generation power semiconductors, researchers need to visualize surface profiles on the order of less than 1 nanometer. The Nikon BW white light interferometric microscope system has been designed to meet these highly exacting needs.
3D laser scanning provides users a metrology tool to obtain a highly accurate representation of the objects' surface for comparison to CAD.
Key terms techniques: Brightfield microscopy, polarization, DIC, interference, metrology