12 August 2009 Wavelet-based phase determination in optical turbulence
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Abstract
Laser beam propagation in a marine environment is of critical importance in the different aspects of Target-in-the-Loop operations. Beam wander and beam spread have been found to be due to turbulence. Wavelet-based phase determination is presented here as a viable approach for analyzing turbulence which is a very significant beam degradation factor. This approach can provide higher beam resolution and significant performance enhancement for laser beam propagation in a marine environment. Wavelet-based phase distribution is particularly appropriate for marine environments which have large vertical gradients in turbulence and are difficult to simulate. First, the distorted beam is put though a shearing interferometer resulting in an interference pattern which is proportional to the gradient of the wavefront. One dimensional signals are taken through the two dimensional interferogram. The Morlet wavelet transform is taken of the one dimensional signal and plotted as a spectrogram. The phase of the signal is equal to the phase of the transform. The phase of the signal carries noise and can identify turbulence in real time. Turbulence is a very significant beam degradation factor which is generated by fluctuations in the index of refraction in a marine environment. Phase can be determined by wavelet-based phase determination, allowing better analysis of beam degradation and improved performance.
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Katharine J. Jones, Katharine J. Jones, "Wavelet-based phase determination in optical turbulence", Proc. SPIE 7463, Atmospheric Optics: Models, Measurements, and Target-in-the-Loop Propagation III, 74630F (12 August 2009); doi: 10.1117/12.825357; https://doi.org/10.1117/12.825357
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