Determination of distortion corrections for a fixed length optical cavity pressure standard

This is the authors' abstract. We don't add key points for this paper.

Optical gas refractometry has enabled new pressure standards to be developed based on a dual Fixed Length Optical Cavity (FLOC) system. NIST in CRADA (collaboration research and development agreement) partnership with MKS Instruments has created a portable FLOC pressure standard based on gas refractivity. A key challenge for accurate measurements is the characterization of cavity distortions when pressurized. A method for determination of the distortion constants is presented based on using two gases of known refractive index. Using this two-gas technique, the distortions on the portable FLOC pressure standard are corrected so that this correction contributes no more than 1 μPa/Pa of uncertainty (k = 1).