Metres to nanometres: measurements in clean and dirty environments

Dimensional and materials analytical measurement techniques can now be used to measure parameters down to the subnanometre level. These techniques are now being used in the real manufacturing world for the production of very large components, e.g. aircraft frames, even though the measurements may be carried out under variable conditions (e.g. changes in temperature and pressure). The combination of advanced high-resolution dimension measurements with novel computation techniques is sufficient for real-time measurement and control of machining operations and the surface quality of materials. This article describes a range of techniques, and gives examples showing measurements in difficult environments. Such developments are already showing economic benefits and are likely to be increasingly used in the manufacture and control of larger aerospace machines, as well as for small nanostructures in semiconductor, biomedical and forensic applications.