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Proceedings Paper

Frequency measurement of refraction index of air for high-resolution laser interferometry
Author(s): Ondrej Cip; Frantisek Petru; Vit Matousek; Josef Lazar
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Paper Abstract

In the work, we present a method for direct measurement of the refraction index of air. We designed two coupled glass cells (one evacuated and the other filled by atmospheric air) inserted to plan-parallel Fabry-Perot resonator (F. P. resonator). Two tunable single-frequency lasers pass laser beams through the evacuated and aired cell simultaneously. Two F.-P. resonators are built up by this way: one of them in evacuated cell and the other in the open air cell. If both lasers are tuned along the resonant modes of F.-P. resonators, an optical frequency difference between two adjacent modes can be identified for each resonator. The evacuated one will have another mode-to-mode difference than the aired resonator. With knowledge of these values we can determine the index of refraction very fast. We verified the method with using Michelson interferometer based technique where a glass cell placed to the measurement arm of the interferometer is evacuated by an oil pump. In this case Michelson interferometer monitors changes of the optical path caused by the process of evacuation. Experimental results achieved by the method will be presented.

Paper Details

Date Published: 17 August 2004
PDF: 5 pages
Proc. SPIE 5458, Optical Micro- and Nanometrology in Manufacturing Technology, (17 August 2004); doi: 10.1117/12.545929
Show Author Affiliations
Ondrej Cip, Institute of Scientific Instruments (Czech Republic)
Frantisek Petru, Institute of Scientific Instruments (Czech Republic)
Vit Matousek, Brno Univ. of Technology (Czech Republic)
Josef Lazar, Institute of Scientific Instruments (Czech Republic)


Published in SPIE Proceedings Vol. 5458:
Optical Micro- and Nanometrology in Manufacturing Technology
Christophe Gorecki; Anand K. Asundi, Editor(s)

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