Improving the Measurement of the Diameter of Si Spheres

Author

Nicolaus, R. Arnold ; Geckeler, Ralf D.

Author_Institution

Phys.-Technische Bundesanstalt, Braunschweig

Volume

56

Issue

2

fYear

2007

fDate

4/1/2007 12:00:00 AM

Firstpage

517

Lastpage

522

Abstract

For a potential new definition of the kilogram using silicon spheres to determine Avogadro´s constant, extremely low measurement uncertainties are required for all influence quantities, e.g., lattice constant, isotopic composition, mass, and volume. For the determination of the volume of the silicon sphere, an unprecedented accuracy for dimensional measurements is required. To reduce the measurement uncertainty, improvements in the PTB interferometer for measuring the spheres were made. Investigations on the wavefront aberration of the objectives and on the bulk temperature of the sphere allow a reduction in the measurement uncertainty to 3.4 10^-8

Keywords

constants; diameter measurement; interferometers; mass measurement; measurement standards; measurement uncertainty; silicon; Avogadro´s constant; PTB interferometer; diameter measurement; extremely low measurement uncertainties; isotopic composition; lattice constant; measurement uncertainty; silicon crystal; silicon spheres; unprecedented accuracy; volume determination; wavefront aberration; Chemical elements; Lattices; Measurement uncertainty; Optical interferometry; Optical surface waves; Performance evaluation; Redundancy; Silicon; Temperature measurement; Volume measurement; Absolute density; Avogadro´s constant; T-type thermocouples; interferometry; silicon crystal; temperature measurement; volume determination;

fLanguage

English

Journal_Title

Instrumentation and Measurement, IEEE Transactions on

Publisher

ieee

ISSN

0018-9456

Type

jour

DOI

10.1109/TIM.2007.890619

Filename

4126897