Displacement measurement with over-determined interferometer

Josef Lazar; Miroslava Holá; Jan Hrabina; Zdeněk Buchta; Ondřej Číp; Jindřich Oulehla

doi:10.1117/12.2010249

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18 December 2012 Displacement measurement with over-determined interferometer

Josef Lazar, Miroslava Holá, Jan Hrabina, Zdeněk Buchta, Ondřej Číp, Jindřich Oulehla

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Proceedings Volume 8697, 18th Czech-Polish-Slovak Optical Conference on Wave and Quantum Aspects of Contemporary Optics; 86970E (2012) https://doi.org/10.1117/12.2010249
Event: 18th Czech-Polish-Slovak Optical Conference on Wave and Quantum Aspects of Contemporary Optics, 2012, Ostravice, Czech Republic

Abstract

We present a concept combining traditional displacement incremental interferometry with a tracking refractometer following the fluctuations of the refractive index of air. This concept is represented by an interferometric system of three Michelson-type interferometers where two are arranged in a counter-measuring configuration and the third one is set to measure the changes of the fixed length, here the measuring range of the overall displacement. In this configuration the two counter-measuring interferometers have identical beam paths with proportional parts of the overall one. The fixed interferometer with its geometrical length of the measuring beam linked to a mechanical reference made of a high thermal-stability material (Zerodur) operates as a tracking refractometer monitoring the atmospheric refractive index directly in the beam path of the displacement measuring interferometers. This principle has been demonstrated experimentally through a set of measurements in a temperature controlled environment under slowly changing refractive index of air in comparison with its indirect measurement through Edlen formula. With locking of the laser optical frequency to fixed value of the overall optical length the concept can operate as an interferometric system with compensation of the fluctuations of the refractive index of air.

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Josef Lazar, Miroslava Holá, Jan Hrabina, Zdeněk Buchta, Ondřej Číp, and Jindřich Oulehla "Displacement measurement with over-determined interferometer", Proc. SPIE 8697, 18th Czech-Polish-Slovak Optical Conference on Wave and Quantum Aspects of Contemporary Optics, 86970E (18 December 2012); https://doi.org/10.1117/12.2010249

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