Interferometry with direct compensation of fluctuations of refractive index of air

0352206 - ÚPT 2011 RIV US eng C - Conference Paper (international conference)
Lazar, Josef - Číp, Ondřej - Čížek, Martin - Hrabina, Jan - Buchta, Zdeněk
Interferometry with direct compensation of fluctuations of refractive index of air.
17th Slovak-Czech-Polish Optical Conference on Wave and Quantum Aspects of Contemporary Optics (Proceedings of SPIE Vol. 7746). Bellingham: SPIE, 2010, 77460E: 1-6. ISBN 978-0-8194-8236-5.
[Slovak-Czech-Polish Optical Conference on Wave and Quantum Aspects of Contemporary Optics /17./. Liptovsky Jan (SK), 06.09.2010]
R&D Projects: GA MŠMT(CZ) LC06007; GA AV ČR KAN311610701; GA MPO FR-TI1/241; GA ČR GA102/09/1276
Institutional research plan: CEZ:AV0Z20650511
Keywords : refractometry * nanopositioning * interferometry * nanometrology
Subject RIV: BH - Optics, Masers, Lasers

We present an experimental arrangement of an interferometric system designed to operate with full compensation for varying refractive index of air in the measuring axis. The concept is based on a principle where the wavelength of the laser source is derived not from an optical frequency of the stabilized laser but from a fixed length being a base-plate or a frame of the whole measuring setup. This results into stabilization of the wavelength of the laser source in atmospheric conditions to mechanical length of suitable etalon made of a material with very low thermal expansion. The ultra-low thermal expanding glass ceramic materials available on the market perform thermal expansion coefficients on the level 10-8 which significantly exceeds the limits of uncertainty posed by indirect evaluation of refractive index of air through Edlen formula. To verify the concept a tracking of laser frequency following the drift of refractive index has been performed.
Permanent Link: http://hdl.handle.net/11104/0191773