Durham University

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Publication details for Dr Tim Morris

Reeves, A. P., Morris, T. J., Myers, R. M., Bharmal, N. A. & Osborn, J. (2016). A tomographic algorithm to determine tip-tilt information from laser guide stars. Monthly Notices of the Royal Astronomical Society 459(1): 333-341.

Author(s) from Durham


Laser Guide Stars (LGS) have greatly increased the sky-coverage of Adaptive Optics (AO) systems. Due to the up-link turbulence experienced by LGSs, a Natural Guide Star (NGS) is still required, preventing full sky-coverage. We present a method of obtaining partial tip-tilt information from LGSs alone in multi-LGS tomographic LGS AO systems. The method of LGS up-link tip-tilt determination is derived using a geometric approach, then an alteration to the Learn and Apply algorithm for tomographic AO is made to accommodate up-link tip-tilt. Simulation results are presented, verifying that the technique shows good performance in correcting high altitude tip-tilt, but not that from low altitudes. We suggest that the method is combined with multiple far off-axis tip-tilt NGSs to provide gains in performance and sky-coverage over current tomographic AO systems.