Arthur S. van de Nes, and Dirk Voigt, “Picometer resolution heterodyne interferometry for short to medium term dimensional stability measurements”, proceedings of the 58th IWK, Ilmenau Scientific Colloquium, Technische Universität Ilmenau, Germany (8-12 September 2014).
A thorough understanding of dimensional drift phenomena at the picometer range, stemming from ageing, temperature changes or mechanical stresses in instrumentation or the object to be measured, is essential for high-end precision engineering and accurate measurements. For that purpose, a balanced double-sided heterodyne interferometer is developed to perform traceable measurements of dimensional drift with an uncertainty of less than 10 pm at the short-term (seconds to minutes), and 100 pm at the medium-term (hours to days). The performance of the instrument is presented by means of a 66 hour long double dead-path difference measurement, demonstrating the desired uncertainty levels during a selected period of 19 hours, while operating in ambient air conditions. The residual pressure related path length difference fluctuations form the current limitation to the measurement uncertainty.
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