Refractive Index Compensation in Over-Determined Interferometric Systems

0385287 - ÚPT 2013 RIV CH eng J - Journal Article
Lazar, Josef - Holá, Miroslava - Číp, Ondřej - Čížek, Martin - Hrabina, Jan - Buchta, Zdeněk
Refractive Index Compensation in Over-Determined Interferometric Systems.
Sensors. Roč. 12, č. 10 (2012), s. 14084-14094. E-ISSN 1424-8220
R&D Projects: GA ČR GA102/09/1276; GA ČR GPP102/11/P820; GA TA ČR TA02010711; GA TA ČR TE01020233; GA MŠMT ED0017/01/01
Institutional support: RVO:68081731
Keywords : refractometry * nanopositioning * interferometry * nanometrology
Subject RIV: BH - Optics, Masers, Lasers
Impact factor: 1.953, year: 2012

We present an interferometric technique based on a differential interferometry setup for measurement under atmospheric conditions. The key limiting factor in any interferometric dimensional measurement are fluctuations of the refractive index of air representing a dominating source of uncertainty when evaluated indirectly from the physical parameters of the atmosphere. Our proposal is based on the concept of an over-determined interferometric setup where a reference length is derived from a mechanical frame made from a material with a very low thermal coefficient. The technique allows one to track the variations of the refractive index of air on-line directly in the line of the measuring beam and to compensate for the fluctuations. The optical setup consists of three interferometers sharing the same beam path where two measure differentially the displacement while the third evaluates the changes in the measuring range, acting as a tracking refractometer. The principle is demonstrated in an experimental setup.
Permanent Link: http://hdl.handle.net/11104/0214593