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Proceedings Paper

Tilt compensation performance enhancement using off-axis higher-order modal wavefront measurements
Author(s): Matthew R. Whiteley; Byron M. Welsh; Michael C. Roggemann
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Paper Abstract

Tilt compensation performance is generally suboptimal when phase measurements from natural or laser guide stars are used as the conjugate phase in an adaptive optics system. Optimal compensation is obtained when the conjugate phase coefficients are estimated from beacon measurements, given knowledge of the correlation between the on-axis object phase and the beacon measurements. In this work, optimal compensation theory is applied to tilt correction for the case of an off-axis higher-order modes are correlated with the on-axis tilt components, a performance gain can be realized when they tilt estimator includes higher-order measurements. For natural guide star compensation, it is shown that equivalent tilt compensation can be achieved at beacon offsets that are three times larger when higher-order modes through Zernike 15 are used in the tilt estimator. For a laser guide star, while tilt information cannot be measured directly due to beam reciprocity, off-axis higher- order modal measurements can be used to estimate tilt components, leading to a maximum Strehl ratio of approximately 0.3 for D/r0 equals 4 and L0/D equals 10.

Paper Details

Date Published: 3 November 1998
PDF: 12 pages
Proc. SPIE 3433, Propagation and Imaging through the Atmosphere II, (3 November 1998); doi: 10.1117/12.330238
Show Author Affiliations
Matthew R. Whiteley, Air Force Institute of Technology (United States)
Byron M. Welsh, Air Force Institute of Technology (United States)
Michael C. Roggemann, Michigan Technological Univ. (United States)

Published in SPIE Proceedings Vol. 3433:
Propagation and Imaging through the Atmosphere II
Luc R. Bissonnette, Editor(s)

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