Referentiemeters

Referentiemeters are standardized length artifacts used as reference lengths in calibration and metrology. A referentiemeter is not an SI unit by itself; rather, it is a physical object whose length is known with a defined uncertainty and linked to the SI meter through a traceability chain. The term is used in some contexts to denote reference length standards that support the calibration of measuring devices and the validation of measurement methods.

Realization and traceability typically involve a precise bar, a calibrated set of gauge blocks, or a small assembly designed to represent a defined length. These artifacts are manufactured from materials with low thermal expansion, such as Invar or Zerodur, and are measured and certified using high-precision techniques, often including laser interferometry. They are stored and used under climate-controlled conditions, with length specified at a reference temperature (commonly around 20°C). Their certified length includes an uncertainty budget that accounts for artifact measurement, environmental factors, and time-dependent drift.

Applications include calibration of length-measuring instruments (rulers, micrometers, calipers), coordinate measuring machines, optical comparators, and other metrological equipment. They may also serve educational purposes or benchmarks in industrial quality control to ensure consistency across production and inspection processes.

Maintenance and lifecycle are important: referentiemeters are handled to minimize damage, periodically re-verified, and replaced when drift or damage pushes them beyond tolerance. They sit alongside other length standards in metrology infrastructures, forming part of the broader system that ensures traceable, accurate length measurement across industries.