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Master Thesis

Réfractométrie absolue basée sur l'hélium

Abstract : The aim of this thesis is the development of a refractometer based on an optical resonator for the measurement of refractive index of gases, including air, with a relative uncertainty of less than 10-8, in the vicinity of atmospheric pressure. We presente here all work performed throughout the duration of the project. Firstly, it was necessary to characterize the optical resonator (Fabry-Perot): measurements of resonance frequencies, of the free spectral range, of the coefficient of thermal expansion, coefficient of distorsion per unit of pressure using helium. A preliminary uncertainty budget of this characterization is supported further index measurements to better than 10-8. The refractometer has been tested by measuring the molar refractivity of pure nitrogen at 532 nm. It was able to measure the index of pure gases wide 10-8 (using helium) and displayed excellent resolution (<10-9). The index of air at ambient conditions (laboratory) could be measured and compared to the index given by Edlen. The difference between the two values is less than the uncertainty associated with Edlen formulas. To reduce the uncertainty in the measurement of the index of air below 10-8, efforts should be made to understanding better the phenomenon of pollution (impurity gas, depositing layers of water mirrors ...) and as well as to improve the seal of the enclosure.
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Master Thesis
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Submitted on : Monday, February 5, 2018 - 11:21:03 AM
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  • HAL Id : dumas-01700756, version 1



Mohamed Kameche. Réfractométrie absolue basée sur l'hélium. Autre. 2013. ⟨dumas-01700756⟩



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