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Proceedings Paper

Air flow and length noise in displacement interferometry
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Paper Abstract

We report on an evaluation of the influence that fast changes of the refractive index has on the uncertainty of interferometric displacement measurement. Measurement of position within a limited range is typical for coordinate measuring systems such as nanometrology standards combining scanning probe microscopy (SPM) with precise positioning. For long-range systems the varying refractive index of air contributes the most to the overall uncertainty. We proposed to extend the principle of compensation of the fluctuations of the refractive index of air through monitoring the optical length within the measuring range of the displacement measuring interferometer. In this contribution we evaluate the level of uncertainty associated with the nature of the fluctuations of the refractive index of air in laser interferometry. We have observed that its fast variations, seen as length noise, are not linearly proportional to the measuring beam path but play a significant role only over distances longer than 50 mm. Over longer distances the length noise rises proportionally. The measurements were performed under conditions typical for metrology SPM systems.

Paper Details

Date Published: 7 January 2015
PDF: 7 pages
Proc. SPIE 9442, Optics and Measurement Conference 2014, 94420D (7 January 2015); doi: 10.1117/12.2176179
Show Author Affiliations
Miroslava Holá, Institute of Scientific Instruments of the AS CR, v.v.i. (Czech Republic)
Ondřej Číp, Institute of Scientific Instruments of the AS CR, v.v.i. (Czech Republic)
Martin Sarbort, Institute of Scientific Instruments of the AS CR, v.v.i. (Czech Republic)
Josef Lazar, Institute of Scientific Instruments of the AS CR, v.v.i. (Czech Republic)


Published in SPIE Proceedings Vol. 9442:
Optics and Measurement Conference 2014
Jana Kovačičinová; Tomáš Vít, Editor(s)

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