7 January 2015 Air flow and length noise in displacement interferometry
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Proceedings Volume 9442, Optics and Measurement Conference 2014; 94420D (2015) https://doi.org/10.1117/12.2176179
Event: Optics and Measurement Conference 2014, 2014, Liberec, Czech Republic
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.
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Miroslava Holá, Miroslava Holá, Ondřej Číp, Ondřej Číp, Martin Sarbort, Martin Sarbort, Josef Lazar, Josef Lazar, } "Air flow and length noise in displacement interferometry", Proc. SPIE 9442, Optics and Measurement Conference 2014, 94420D (7 January 2015); doi: 10.1117/12.2176179; https://doi.org/10.1117/12.2176179
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