title: Comparison measurements of low-pressure between a laser refractometer and ultrasonic manometer.
abstract: We have developed a new low-pressure sensor which is based on the measurement of (nitrogen) gas refractivity inside a Fabry-Perot cavity. We compare pressure determinations via this laser refractometer to that of well-established ultrasonic manometers throughout the range 100 Pa to 180 000 Pa. The refractometer demonstrates 10(-6) ⋅ p reproducibility for p > 100 Pa, and this precision outperforms a manometer. We also claim the refractometer has an expanded uncertainty of U(pFP) = [(2.0 mPa)(2) + (8.8 × 10(-6) ⋅ p)(2)](1/2), as realized through the properties of nitrogen gas; we argue that a transfer of the pascal to p < 1 kPa using a laser refractometer is more accurate than the current primary realization.
authors.affiliation: National Institute of Standards and Technology, 100 Bureau Dr, Gaithersburg, Maryland 20899, USA.
authors.forename: Patrick F
authors.initials: PF
authors.lastname: Egan
authors.affiliation: National Institute of Standards and Technology, 100 Bureau Dr, Gaithersburg, Maryland 20899, USA.
authors.forename: Jack A
authors.initials: JA
authors.lastname: Stone
authors.affiliation: National Institute of Standards and Technology, 100 Bureau Dr, Gaithersburg, Maryland 20899, USA.
authors.forename: Jacob E
authors.initials: JE
authors.lastname: Ricker
authors.affiliation: National Institute of Standards and Technology, 100 Bureau Dr, Gaithersburg, Maryland 20899, USA.
authors.forename: Jay H
authors.initials: JH
authors.lastname: Hendricks