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.

Length and Dimensional Measurement at NIST



Dennis A. Swyt


This paper reports on the past, present, and future of length and dimensional measurements at NIST. It covers the evolution of the SI unit of length through its three definitions and the evolution of NBS-NIST dimensional measurement from early linescales and gage blocks to a future of atom-based dimensional standards. Current capabilities include dimensional measurements over a range of fourteen orders of magnitude. Uncertainties of measurements on different types of material artifacts range down to 7?? ?10-8 at 1 meter and 8 picometers at 300 pm. Current work deals with a broad-range of areas of dimensional metrology. These including: large-scale coordinate systems; complex form; microform; surface finish; two-dimensional grids; optical, scanning-electron, atomic-force, and scanning-tunneling microscopies; atomic-scale displacement; and atom-based artifacts.
Journal of Research of the National Institute of Standards and Technology


atomic force microscopy (AFM), coordinate measuring machines, dimensional, Fabry-Perot, laser, laser trackers, length, measurements, metrology, optical, optical heterodyne, scanning electron microscopy(SEM), scanning tunneling microscopy (STM), theodolites, traceability, x-ray interferometry


Swyt, D. (2001), Length and Dimensional Measurement at NIST, Journal of Research of the National Institute of Standards and Technology, [online], (Accessed May 28, 2024)


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

Created January 1, 2001, Updated February 19, 2017