Toward subnanometer uncertainty in interferometric length measurements of short gauge blocks.
A primary-level comparator, with a reproducibility of 0.2 nm and intended for realization of a Systeme International length unit in the range of 1-100 mm, is reported. High-precision differential measurements of phase change on reflection from blocks and end plates are demonstrated. A set of experiments has been developed to measure systematic error associated with nonideal interferometer optics and deviations from flatness of an auxiliary plate. For specially selected high-grade 6-mm blocks, reproducible wringing has been achieved with a random uncertainty in length measurements of 0.1-0.2 nm. Subnanometer wear-off of the blocks as a result of the cleaning has been detected. Under the conditions of reproducible wringing, the accuracy of the length measurements is evaluated to be in the 2-3-nm range for 6-mm blocks.
Malinovsky
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Diretoria de Metrologia Científica e Industrial, Divisão de Optica, National Metrology Institute, Avenada Nossa Senhora das Graças 50 Xerém 25250-020 Duque de Caxias, Rio de Janeiro, Brazil. igor.malinovsky@usa.net
Titov
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Dutra
J A
JA
Belaïdi
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H
França
R dos S
Rdos S
Massone
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CA