Development of an optical force balance for low mass at LNE-CNAM

The dissemination of the kilogram, spanning from the national prototype to sub-multiples ranging from 500 g to 100 μg, entails over 200 comparisons, resulting in heightened uncertainty propagation. To improve this issue, alternative realisations are imperative. Over recent years, LNE-CNAM has developed an instrument for absolute laser power measurement employing pressure radiation and pyrolytic graphite properties. Capitalising on these advancements a prototype of a novel balance has been devised for low-mass and force measurements within the 0.6 nN–100 nN range with a targeted relative standard uncertainty of 1 %. This balance exploits the diamagnetic attributes of pyrolytic graphite to levitate a pendulum, achieving high sensitivity with magnetic support. This traceability is ensured by a traceable optical balance developed at LNE-CNAM.

Preliminary assessments on the first balance version demonstrate a sensitivity of 9.3 μrad·nN⁻¹.