Metrology in the sense of quality-assured measurement, i.e. the two concepts – metrological traceability and measurement uncertainty – specifically at the nano-scale (1 nm – 100 nm).
Metrological traceability – where possible, to universal measurement references of the SI system – ensures that different measurement results – those made at different times and different locations, and even different measurement quantities can be compared objectively. Products and processes assessed for conformity using traceable test results will themselves be comparable and robust.
Measurement uncertainty is a declared level of quality in the measurement result. It is an estimate of unknown measurement errors. Measurement uncertainty is always needed when judging whether different measured values are equal, or not. It is also essential in assessing the risks of incorrect decisions of compliancy when comparing a test result with a specification limit. The latter is a key concern in nanometrology, since decisions of conformity assessment, for instance in regulatory contexts, are often of concern.
“Introductory Guide to Nanometrology”, P-E Hansen, G Roebben, L R Pendrill et al. 2011, CO-NANOMET report, ISBN: 978‐0‐9566809‐1‐4, http://www.euspen.eu/content/swf/euspen4/