Length and dimensional measurements at NIST

Abstract

This paper discusses 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 m at 1 m and 8 picometers (pm) at 300 pm. Current work deals with a broad range of areas of dimensional metrology. These include: 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.

Towards near perfect crystals with only well-characterized imperfections

“…Since its inauguration, the National Bureau of Standards (NBS) contributed to that progress by its careful critical measurements at the highest attainable sensitivity, as is well documented in Refs. [1] and [2]. …”

Invited Article: Concepts and tools for the evaluation of measurement uncertainty

“…In this case, the reference value would be the "the length of the path traveled by light in vacuum during a time interval of 1/299 792 458 of a second," which is 1 m by definition, 10 and may be realized using an iodine stabilized helium-neon laser 11 or optical frequency combs. 12,13 The comparison involved in measurement may be direct, as in the example just given, or it may be indirect, as when the volume of the box is determined by multiplying its length, width, and height, rather than by comparing the volume of the box against the volume of water that the box displaces when fully immersed in it.…”

Dynamics of a Carriage System of Comparator for Calibrating the Line Standards of Length

“…The new generation of precision scale production and calibration systems must meet significantly higher accuracy and efficiency requirements (Swyt 2001;Webb and Jones 2004;Bosse and Flugge 2002;Kasparaitis et al 2012). To fulfill these requirements, accuracy parameters of precision scales should be metrologically linked to those of higher etalons already in place during the manufacturing process.…”

“…*Corresponding author's email: Vadim.moksin@vgtu.it The relevance of the accurate and fast detection of divisions of line standards of length is primarily determined by the constantly increasing requirements of precision scale calibration productivity (BIPM 2003;RAENG, 2004;Swyt 2001). The new generation of precision scale production and calibration systems must meet significantly higher accuracy and efficiency requirements (Swyt 2001;Webb and Jones 2004;Bosse and Flugge 2002;Kasparaitis et al 2012).…”