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Proceedings Paper

Estimation of optical turbulence characteristics from Shack Hartmann wavefront sensor measurements
Author(s): Terry J. Brennan; David C. Mann
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Paper Abstract

In the field of optical propagation through the atmosphere a knowledge of optical turbulence strength and other key statistical parameters is crucial for performance prediction and system design. This work presents techniques for reliably estimating the most essential parameters of optical turbulence, namely r0, the Fried coherence length, fG, the Greenwood frequency, and l0, the inner scale of turbulence from Shack-Hartmann wavefront sensor measurements. The earliest approaches for estimating r0 were based on MTF measurements.1 The MTF approach requires accurate calibration and stability of the system MTF which is often problematic. Astronomers have used differential motion and scintillation to measure seeing conditions.2-5 Others have used the slope structure function estimated from a Hartmann wavefront sensor principally for r0 estimation.6 We have shown that the slope discrepancy7 or rotational component of the slopes can be used effectively in turbulence estimates.8 The techniques we describe here can be used to estimate r0, fG, and l0. The inner scale estimate is based on the assumption of the Hill spectrum for refractive index fluctuations.9-11 A high resolution, high frame rate, mobile sensor has been developed to utilize these estimation techniques. Section 2 describes the estimation techniques. Results from field measurement campaigns will be presented in Section 3.

Paper Details

Date Published: 12 August 2010
PDF: 16 pages
Proc. SPIE 7816, Advanced Wavefront Control: Methods, Devices, and Applications VIII, 781602 (12 August 2010); doi: 10.1117/12.862808
Show Author Affiliations
Terry J. Brennan, The Optical Sciences Co. (United States)
David C. Mann, The Optical Sciences Co. (United States)


Published in SPIE Proceedings Vol. 7816:
Advanced Wavefront Control: Methods, Devices, and Applications VIII
David C. Dayton; Troy A. Rhoadarmer; Darryl J. Sanchez, Editor(s)

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