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1 September 2006 Mitigation of dynamic wavefront distortions using a modified simplex optimization approach
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Laser beam propagating through the dynamically changing atmosphere is subjected to severe wavefront distortions caused by the optical turbulence. The resulting spatial and temporal fields of the refractive index lead to performance degradation in the form of reduced signal power and increased BER, even for short link ranges. An electrically addressed liquid crystal spatial light modulator (SLM) is proposed to perform correction of the optical path difference (OPD) pattern resulting from the atmospheric distortions. Controlling every individual pixel of the SLM is a rigorous and time-consuming task that calls for a stable and simple procedure that could be performed in real-time. This could be addressed by approximating the phase profile of the distorted beam using Zernike formalism, which provides efficient mapping between large number of SLM pixels and smaller number of coefficients of Zernike polynomials. A possible solution to the dynamic correction problem is the application of Simplex optimization by Nelder and Mead, which is well known for fast improvement of an optimization metric. As has been shown before, this approach presents a problem of locking up in local minima while correcting dynamic changes. This paper presents experimental results of different approaches to resolve this problem by modifying simplex procedure as well as modification in a previously presented experimental setup.
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Rahul M. Khandekar and Vladimir V. Nikulin "Mitigation of dynamic wavefront distortions using a modified simplex optimization approach", Proc. SPIE 6304, Free-Space Laser Communications VI, 63041J (1 September 2006);

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