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The NIST Length Scale Interferometer



John S. Beers, William B. Penzes


The National Institute of Standards and Technology (NIST) interferometer for measuring graduated length scales has been in use since 1965. It was developed in response to the redefinition of the meter in 1960 from the prototype platinum-iridium bar to the wavelength of light. The history of the interferometer is recalled, and its design and operation described. A continuous program of modernization by making physical modifications, measurement procedure changes and computational revisions is described, and the effects of these changes are evaluated. Results of a long-term measurement assurance program, the primary control on the measurement process, are presented, and improvements in measurement uncertainty are documented.
Journal of Research of the National Institute of Standards and Technology


graduated scales, interferometry, length, measurement assurance, measurement uncertainty


Beers, J. and Penzes, W. (1999), The NIST Length Scale Interferometer, Journal of Research of the National Institute of Standards and Technology, [online], (Accessed April 20, 2024)
Created May 1, 1999, Updated February 19, 2017