Constrained matched filtering for extended dynamic range and improved noise rejection for Shack–Hartmann wavefront sensing

摘要

We recently introduced matched filtering in the context of astronomical Shack–Hartmann wavefront sensingnwith elongated sodium laser beacons [Appl. Opt. 45, 6568 (2006)]. Detailed wave optics Monte Carlo simu-nlations implementing this technique for the Thirty Meter Telescope dual conjugate adaptive optics systemnhave, however, revealed frequent bursts of degraded closed loop residual wavefront error [Proc. SPIE 6272,n627236 (2006)]. The origin of this problem is shown to be related to laser guide star jitter on the sky thatnkicks the filter out of its linear dynamic range, which leads to bursts of nonlinearities that are reconstructedninto higher-order wavefront aberrations, particularly coma and trifoil for radially elongated subaperturenspots. An elegant reformulation of the algorithm is proposed to extend its dynamic range using a set of linearnconstraints while preserving its improved noise rejection and Monte Carlo performance results are reportednthat confirm the benefits of the method. © 2008 Optical Society of America