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21 August 2003 Anatomy of the slope discrepancy structure function: characterization of turbulence
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A new approach, for estimating r0 and the Greenwood frequency from wavefront sensor measurements, is introduced. Unlike other techniques, which use phase statistics calculated from reconstructed wavefront sensor measurements, this approach makes use of the slope discrepancy, the component of the measurement that is not reconstructed by a least squares reconstructor. It is shown that the r0 estimator based on the slope discrepancy is a high degree-of-freedom estimator with a much smaller estimation variance than estimates based on the phase variance. An new temporal atmospheric sample rate, f02), is introduced in this work. This quantity is calculated from the slope discrepancy structure function and sets the minimum required sampling rate to maintain the residual wavefront error below ε2/K for a system dependent gain, K. For Kolmogorov turbulence statistics it is shown that the Greenwood frequency is related to f0 by fG=f0(K(2π/20)2)/40. In non-Kolmogorov turbulence, f0 continues to be a legitimate specification of sampling requirements. These results are all illustrated with wave optics simulations.
© (2003) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Terry J. Brennan "Anatomy of the slope discrepancy structure function: characterization of turbulence", Proc. SPIE 5087, Laser Systems Technology, (21 August 2003);

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