| AVS 64th International Symposium & Exhibition | |
| Vacuum Technology Division | Monday Sessions |
| Session VT+MN-MoM |
| Session: | Progress with Measurement in Vacuum |
| Presenter: | Jacob Ricker, NIST |
| Authors: | J.E. Ricker, NIST J. Hendricks, NIST G.E. Scace, NIST P. Egan, NIST J.A. Stone, NIST |
| Correspondent: | Click to Email |
NIST is constructing and testing a new refractometer, referred to as the Variable length optical cavity (VLOC), that will redefine how pressure and vacuum is measured. NIST has shown in previous talks and papers that this technique will replace all mercury manometers in the near future. However, the critical final piece of this project is to base the traceability of pressure measurements to fundamental constants of the universe and not on the physical artifacts like mercury density in a manometer. Theoretical quantum mechanics have been used to precisely calculate the refractivity (n-1) of a gas. NIST will experimentally verify these calculations and provide experimental measurements of refractivity for other gasses/mixtures.
The engineering of the VLOC will be discussed along with limitations and technical complications that have arisen. Specifically, the distortions of the optical cavities and methods to overcome these limitations. Additionally, the steps required to maintain ultra-high purity gas will be discussed. Finally, the testing and final steps to achieve full operation will be discussed and the relation to the 2018 redefinition of the Boltzmann constant.