Ultimate turbulence experiment: simultaneous measurements of Cn2 near the ground using six devices and eight methods

Lydia Yatcheva; Rui Barros; Max Segel; Detlev Sprung; Erik Sucher; Christian Eisele; Szymon Gladysz

doi:10.1117/12.2195029

8 October 2015 Ultimate turbulence experiment: simultaneous measurements of C_n² near the ground using six devices and eight methods

Lydia Yatcheva, Rui Barros, Max Segel, Detlev Sprung, Erik Sucher, Christian Eisele, Szymon Gladysz

Author Affiliations +

Proceedings Volume 9641, Optics in Atmospheric Propagation and Adaptive Systems XVIII; 964105 (2015) https://doi.org/10.1117/12.2195029
Event: SPIE Remote Sensing, 2015, Toulouse, France

Abstract

We have performed a series of experiments in order to simultaneously validate several devices and methods for measurement of the path-averaged refractive index structure constant ( 𝐶_𝑛²). The experiments were carried out along a horizontal urban path near the ground. Measuring turbulence in this layer is particularly important because of the prospect of using adaptive optics for free-space optical communications in an urban environment. On one hand, several commercial sensors were used: SLS20, a laser scintillometer from Scintec AG, BLS900, a largeaperture scintillometer, also from Scintec, and a 3D sonic anemometer from Thies GmbH. On the other hand, we measured turbulence strength with new approaches and devices developed in-house. Firstly, an LED array combined with a high-speed camera allowed for measurement of 𝐶_𝑛² from raw- and differential image motion, and secondly a two-part system comprising a laser source, a Shack-Hartmann sensor and a PSF camera recoded turbulent modulation transfer functions, Zernike variances and angle-of-arrival structure functions, yielding three independent estimates of 𝐶_𝑛². We compare the measured values yielded simultaneously by commercial and in-house developed devices and show very good agreement between 𝐶𝑛 2 values for all the methods. Limitations of each experimental method are also discussed.

Citation Download Citation

Lydia Yatcheva, Rui Barros, Max Segel, Detlev Sprung, Erik Sucher, Christian Eisele, and Szymon Gladysz "Ultimate turbulence experiment: simultaneous measurements of C_n² near the ground using six devices and eight methods", Proc. SPIE 9641, Optics in Atmospheric Propagation and Adaptive Systems XVIII, 964105 (8 October 2015); https://doi.org/10.1117/12.2195029

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