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Proceedings Paper

High sensitivity wave tilt measurements with optical vortex interferometer
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Paper Abstract

Optical Vortex Interferometer (OVI) is a new type of interferometer which is based on the regular net of optical vortices (OV)1,2,3. The net is generated by the interference of three plane waves. The idea of the measurement with the OVI is as follows: if one of the interfering waves is distorted then the geometry of the vortex net is changed. In our case one of the wavefronts was tilted. We can calculate the tilt of the wave by tracking the change of vortices positions. Basically it is sufficient to determine the relative change in the positions of three optical vortices (vortex triplet). If there are 200 vortices in the measurement field then we can choose about 1 million vortex triplets. The important advantage of this measurement is that two rotation angles through two perpendicular axes can be determined into one step. Also the mechanical vibrations are automatically subtracted and the system is simple. Our first results show5 that using about 1000 triplets we can measure the small angle with an error of 1.2arcsec (on the base of standard deviation). Performing the analysis we observed however that the real sensitivity of the OVI is higher than resolution resulting from the basic analysis methods. We observe the change of the histogram of the calculated angle if the tilt by the angle of 0.05arcsec is introduced. In the paper we analyze this effect. If the rotation angle is small then optical vortices change their positions by the small part of the distance between the measurement points. Due to detector quantization some of vortices can be still localized as lying in the same measurement point while the others are localized as shifted. This effect causes the histogram shift. The method of recomputing such histogram shift into the value of rotation angle is presented. In result we can achieve 6-10 times better resolution of the OVI.

Paper Details

Date Published: 22 April 2006
PDF: 7 pages
Proc. SPIE 6189, Optical Sensing II, 618907 (22 April 2006); doi: 10.1117/12.662565
Show Author Affiliations
Agnieszka Popiołek-Masajada, Wrocław Univ. of Technology (Poland)
M. Borwińska, Wrocław Univ. of Technology (Poland)

Published in SPIE Proceedings Vol. 6189:
Optical Sensing II
Brian Culshaw; Anna G. Mignani; Hartmut Bartelt; Leszek R. Jaroszewicz, Editor(s)

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