A novel interferometer for dimensional measurement of a silicon sphere

Nicolaus, R.A.; Bönsch, G.

doi:10.1109/19.571915

Cited by 40 publications

(32 citation statements)

References 6 publications

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“…The centre of the range m between the extrapolation to zero energy of all measured data and the value at the smallest energy (23 eV) was assumed as measurement result, because of the unknown value of the threshold for sputter and reflection effects. parameter represents the mass of a single gold atom according to m Au = e 1 I dm dt (15) or m Au = e m t 0 I dt (16) The mass of a gold atom has thus been measured with a relative uncertainty of 1.5% and a deviation from the product of the tabulated values of A Au and m u of 0.6%. Sputter yields of, e.g., 6.2 at 310 eV and of 0.015 at 23 eV have been derived from the measurement results as well.…”

Section: Resultsmentioning

confidence: 99%

“…The volume is being determined by measuring diameters either with a Fizeau interferometer that measures about 16,000 phase differences (diameters) simultaneously or with a FabryPerot etalon coupled with a large number of single measurements [15]. In order to fit the wave fronts to the curvature of the sphere, two different modifications are used, respectively: expanded light beams with spherical wave fronts in order to obtain a topographical map simultaneously or light beams with a very small beam diameter collimated by a lens so that concentric circular fringes are observed.…”

Section: Density Of Silicon Volume Standardsmentioning

confidence: 99%

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Primary mass standard based on atomic masses

Becker

Gläser

2006

International Journal of Mass Spectrometry

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Section: Resultsmentioning

confidence: 99%

Section: Density Of Silicon Volume Standardsmentioning

confidence: 99%

Primary mass standard based on atomic masses

Becker

Gläser

2006

International Journal of Mass Spectrometry

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“…With an uncertainty in the nm-range for the length measurement an overall uncertainty of about 3-10-for the Avogadro's constant could be achieved [1]. The spheres interferometer of PTB The main idea of the spheres interferometer of PTB is the spherical symmetry [2]. It base on spherical wavefronts and spherical reference faces, matching the sphere to be measured.…”

Section: Introductionmentioning

confidence: 99%

Diameter determination of Avogadro sphere #1 and #2

Nicolaus

2004

2004 Conference on Precision Electromagnetic Measurements

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In the scope of the new determination of Avogadro's constant, NA, the spheres interferometer of PTB was developed to measure the volume of the Avogadro sphere. The interferometer is based on spherical reference plates and spherical beams of rays. This allows not only one diameter in the center to be measured, but a big amount of diameter measurements available in a 600 field of view. With all orientations of this 60°cone a sphere is characterized by 500 000 diameter values. Avogadro sphere #1 of PTB and Avogadro sphere #2 of IMGC have been measured in 40 different orientations, so that fundamental knowledge of the spheres can be given. The additional information of surface topography leads to better understanding of uncertainty. IntroductionFor the Avogadro project with natural Silicon, which has been initiated in PTB, four measurements contribute to the value of NA: the measurement of the lattice constant and the determination of the molar mass of a sample from the silicon used, and mass and volume determination of a silicon sphere of same origin. Three spheres, Avo#1 to Avo#3, were made from WASO 04. The volumes of the spheres Avo#I and Avo#2 were determined by interferometric measurements at PTB. The volume of each sphere was calculated from about 500 000 diameter measurements. With an uncertainty in the nm-range for the length measurement an overall uncertainty of about 3-10-for the Avogadro's constant could be achieved [1].

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“…There are many routs to determining the volume of the single crystal silicon sphere 7 , however, it is proved that the method of using an optical interferometer is a most valid one 8,9,10 . Since the surface of the single crystal silicon sphere is covered by an oxide layer (typically 3-10nm) grown in the process of fabrication, the effect of phase retardation on the reflection at the oxide layer causes a remarkable systematic difference when it is measured by an optical interferometer, which is also the primary cause of the uncertainty of the diameter determination 7 .…”

Section: Introductionmentioning

confidence: 99%

A novel ellipsometer for measuring thickness of oxide layer on the surface of silicon sphere

Zhang

2007

SPIE Proceedings

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The Avogadro constant NA is used as one of the several possible routes to redefinition of the kilogram in metrology today. Usually in order to accurately determine NA, the volume of a perfect single crystal silicon sphere of nearly 1 kg mass should be measured with a high relative uncertainty, i.e. about 1 10 -8 . However, the oxide layer grown on the surface of the silicon sphere causes a remarkable systematic difference between the measured and real diameters. A novel ellipsometer has been developed to determine the thickness of the oxide layer accurately and automatically. The arrangement of this instrument is suitable for measuring the layer on the sphere surface. What's more, the measuring is faster by optimizing the parameters and developing the algorithm of calculating the thickness and refractive index of the oxide layer. The preliminary simulation result has present. Thus, the uncertainty of the diameter measurement caused by the oxide layer can be observably reduced. And the further improving of this ellipsometer is discussed in the end.

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A novel interferometer for dimensional measurement of a silicon sphere

Cited by 40 publications

References 6 publications

Primary mass standard based on atomic masses

Primary mass standard based on atomic masses

Diameter determination of Avogadro sphere #1 and #2

A novel ellipsometer for measuring thickness of oxide layer on the surface of silicon sphere

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