Analysis of the Improvement in Sky coverage for TMT NFIRAOS
Lianqi Wang, Brent Ellerbroek, and Luc Gilles
The scientific utility of laser guide star based adaptive optics (AO) systems depend upon high sky coverage. Previously we reported a high fidelity sky coverage analysis of an ad hoc split tomography (AHST) control algorithm and a post-processing simulation technique. In this paper, we will validate the post-processing sky coverage analysis using integrated simulations of both high order (Laser guide star) and low order loops (NGS guide star) with our efficient simulation software, multi-threaded AO simulator (MAOS). We will show a newly identified important term in the noise model that improves the performance by more properly regularizing the reconstructor. We Will also present the sky coverage results of a newer minimum variance split tomography (MVST) algorithm, and show that it brings a median improvement at zenith of 21 nm RMS OPD error over AHST without complicates the real time controller. The improvement is more significant for worse asterisms and/or for higher zenith angles.