Practical Fabry-Perot displacement interferometry in ambient air conditions with subnanometer accuracy

Dirk Voigt, Arthur S. van de Nes, and Steven A. van den Berg, “Practical Fabry-Perot displacement interferometry in ambient air conditions with subnanometer accuracy”, invited paper, SPIE 2014 Optics & Photonics, Interferometry XVII: Techniques and Analysis, Proc. of SPIE 9203, 920308 (2014), doi: 10.1117/12.2060537.

Abstract
Fabry-Perot displacement interferometry (FPI) offers high sensitivity and resolution with direct traceability to optical frequency standards. FPI can provide means for demanding calibration tasks in precision engineering and high-tech systems. We report on our investigation of the measurement methodology applied to highest precision capacitive displacement sensors. We use a dedicated metrological FPI instrumentation that provides an actuated reference target with a relatively large traceable displacement stroke. The envisaged sub-nanometer measurement uncertainty seems very challenging under practical ambient atmospheric conditions and with the necessary sensor mounting components. In anticipation of these limitations, we propose a new FPI instrumental configuration with a very short cavity and discuss expected benefits, most importantly the very low sensitivity to air refractive index variations and the versatility for practical calibration purposes. We aim again for sub-nanometer measurement uncertainty and report on the status of the experimental set-up for this short cavity FPI.

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For more information contact dvoigt@vsl.nl