The various units of the SI for the different measurement quantities are defined at a level where the actual measurement accuracy is highest. Thus for example the unit of mass is set at the one-kilogram level, since weighings at heavier and lighter levels are less accurate – heavier weights are more difficult to handle while smaller weights are more easily perturbed. Weighing machines similarly work best close to the kilogram level.
These trends – where accuracy generally falls towards both shorter ranges and longer ranges – are similar for many measurement quantities.
Measurements at the nanoscale (1 nm – 100 nm) are no exception. Because of this, it will be increasingly more challenging in nanometrology to establish metrological traceability and to reach target measurement uncertainties.
Examples of nanometrological challenges include:
- Longer chains of metrological traceability
- New nanometric reference materials and standards
- Need for new measurement instrumentation and test methods working in the nanoscale
- New characteristics unique to the nanoscale need to be measured
- Measurements in challenging environments, e.g. ultra-high vacuum