| AVS 66th International Symposium & Exhibition | |
| Vacuum Technology Division | Monday Sessions |
| Session VT-MoM |
| Session: | Pumping, Outgassing, leaks, and Vacuum Pressure Measurement |
| Presenter: | Kevin Douglass, National Institute of Standards and Technology (NIST) |
| Authors: | K.O. Douglass, National Institute of Standards and Technology (NIST) J.E. Ricker, National Institute of Standards and Technology (NIST) J. Hendricks, National Institute of Standards and Technology (NIST) |
| Correspondent: | Click to Email |
Towards the goal of quantum-based traceability of the Pascal, NIST has developed an optical pressure measurement system where traceability is achieved through accurate quantum mechanical calculations of the refractivity virial coefficients. Extremely accurate measurements of refractive index are possible; however, traceability is currently through the mercury manometer. Primary traceability for the NIST Fixed Length Optical Cavity (FLOC) will require an independent approach, relying solely on refractive index type measurements. A critical step in achieving primary traceability for the FLOC is determining the pressure dependent distortion terms. This is a major challenge because the pressure and the distortion term need to be determined simultaneously. A dual-wavelength approach can provide two measurements in-order to solve for the two unknown variables. The operational wavelengths for this measurement are at 633 nm and 1542 nm. The dual-wavelength approach and current results will be presented.