Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Temperature stabilization system with millikelvin gradients for refractometry



Patrick F. Egan, Jack A. Stone Jr.


Refractometry of air is a central problem for interferometer-based dimensional measurements. Refractometry at the 10^{-9} level is only valid if air temperature gradients are controlled at the millikelvin level. Very precise tests of second-generation NIST refractometers involve comparing two instruments (two optical cavities made from ultralow expansion glass) that are located in nominally the same environment; temperature gradients must be kept below a few millikelvin to achieve satisfactory precision of these tests. In this paper we describe a thermal stabilization scheme that maintains
Proceedings Title
2010 NCSL International Workshop and Symposium
Conference Dates
July 25-29, 2010
Conference Location
Providence, RI
Conference Title
2010 NCSL International Workshop and Symposium: 21st Century Innovations in Metrology


Temperature stabilization, Refractometry, Thermometry


Egan, P. and Stone, J. (2010), Temperature stabilization system with millikelvin gradients for refractometry, 2010 NCSL International Workshop and Symposium, Providence, RI, [online], (Accessed June 16, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created July 25, 2010, Updated February 19, 2017