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Proceedings Paper

Turbulence characterization by studying laser beam wandering in a differential tracking motion setup
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Paper Abstract

The Differential Image Motion Monitor (DIMM) is a standard and widely used instrument for astronomical seeing measurements. The seeing values are estimated from the variance of the differential image motion over two equal small pupils some distance apart. The twin pupils are usually cut in a mask on the entrance pupil of the telescope. As a differential method, it has the advantage of being immune to tracking errors, eliminating erratic motion of the telescope. The Differential Laser Tracking Motion (DLTM) is introduced here inspired by the same idea. Two identical laser beams are propagated through a path of air in turbulent motion, at the end of it their wander is registered by two position sensitive detectors-at a count of 800 samples per second. Time series generated from the difference of the pair of centroid laser beam coordinates is then analyzed using the multifractal detrended fluctuation analysis. Measurements were performed at the laboratory with synthetic turbulence: changing the relative separation of the beams for different turbulent regimes. The dependence, with respect to these parameters, and the robustness of our estimators is compared with the non-differential method. This method is an improvement with respect to previous approaches that study the beam wandering.

Paper Details

Date Published: 1 October 2009
PDF: 8 pages
Proc. SPIE 7476, Optics in Atmospheric Propagation and Adaptive Systems XII, 74760D (1 October 2009); doi: 10.1117/12.830234
Show Author Affiliations
Darío G. Pérez, Pontificia Univ. Católica de Valparaíso (Chile)
Luciano Zunino, Ctr. de Investigaciones en Ópticas A.C. (Argentina)
Univ. Nacional de La Plata (Argentina)
Damián Gulich, Ctr. de Investigaciones en Óptica, A.C. (Argentina)
Gustavo Funes, Ctr. de Investigaciones en Óptica, A.C. (Argentina)
Mario Garavaglia, Univ. Nacional de la Plata (Argentina)

Published in SPIE Proceedings Vol. 7476:
Optics in Atmospheric Propagation and Adaptive Systems XII
Anton Kohnle; Karin Stein; John D. Gonglewski, Editor(s)

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