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Proceedings Paper

Interferometry with suppression of fast fluctuations of the refractive index of air for nanometrology
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Paper Abstract

We present an interferometric technique based on differential interferometry setup for measurement in the subnanometer scale in atmospheric conditions. The motivation for development of this ultraprecise technique is coming from the field of nanometrology. The key limiting factor in any optical measurement are fluctuations of the refractive index of air representing the greatest source of uncertainty. Our proposal is based on the concept of combining overdetermined interferometric setup where a reference wavelength is derived from a mechanical reference for compensation of fast fluctuations and traditional indirect evaluation of the refractive index compensating on the other hand the long-term drift of the mechanical reference caused by thermal expansion. The technique allows to track the variations of the refractive index of air on-line directly in the line of the measuring beam and to compensate for the fluctuations. The optical setup consists of three interferometers sharing the same beam path where two measure differentially the displacement while the third evaluates the changes in the measuring range acting as a tracking refractometer. The principle is demonstrated on an experimental setup and a set of measurements describing the performance is presented.

Paper Details

Date Published: 10 October 2013
PDF: 6 pages
Proc. SPIE 8916, Sixth International Symposium on Precision Mechanical Measurements, 89161J (10 October 2013); doi: 10.1117/12.2035553
Show Author Affiliations
Josef Lazar, Institute of Scientific Instruments (Czech Republic)
Miroslava Hola, Institute of Scientific Instruments (Czech Republic)
Jan Hrabina, Institute of Scientific Instruments (Czech Republic)
Zdenek Buchta, Institute of Scientific Instruments (Czech Republic)
Ondrej Cip, Institute of Scientific Instruments (Czech Republic)


Published in SPIE Proceedings Vol. 8916:
Sixth International Symposium on Precision Mechanical Measurements
Shenghua Ye; Yetai Fei, Editor(s)

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