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Design of a cell-based refractometer with small end-effects



Patrick Egan, Jack A. Stone Jr.


In cell-based laser refractometers, interferometer pathlength uncertainty introduced by deformation and stress in the windows through which the beams pass can be the chief factor limiting measurement accuracy. The fractional contribution of pathlength uncertainty to our recent determination of the Boltzmann constant was 9.8 × 10-6, and more than two times larger than the next largest uncertainty component. We briefly describe the error, and propose a design in which cell window effects contribute less than 3 × 10-6 to the measurement of helium refractivity; performance that would be competitive with state-of-the-art primary thermometry and barometry.
Proceedings Title
CPEM 2018 Digest
Conference Dates
July 8-13, 2018
Conference Location
Paris, FR
Conference Title
Conference on Precision Electromagnetic Measurements (CPEM) 2018


Egan, P. and Stone Jr., J. (2018), Design of a cell-based refractometer with small end-effects, CPEM 2018 Digest, Paris, FR, [online], (Accessed April 17, 2024)
Created July 7, 2018, Updated April 11, 2022