Simulations of a SCAO System for an E-ELT telescope using the pyramid wavefront sensor: recent results
Aurea Garcia-Rissmann, Miska Le Louarn (1)
(1) European Southern Observatory
Updated results obtained from simulations of a single-conjugated adaptive optics (SCAO) system for a 42m telescope are presented in this work. The modulated pyramid wavefront sensor (PWFS), which has been preferred in some projects for its versatility and sensitivity, is used in these simulations. The main objective of this work is to evaluate the performance of such SCAO system under different parameters (loop gain, modulation, truncated SVD mode), sensing wavelengths, atmospheric coherence scales and NGS magnitudes. Always measuring the Strehl ratio in the K-band, we have verified that the overall performance tends to be poorer as the sensing wavelength becomes shorter. The loop gain optimal range is dependent on the SVD truncation threshold used to build the command matrix, and a non-modulated PWFS produces in general poorer results when compared to modulated cases, being this especially true for the R-sensing band. The default atmospheric model adopted was a von Karman with r0=0.13m (at 500nm) and outer scale of 25m, but poorer and better seeing conditions have also been tested. We also show how the Strehl is affected by the incidence of different photon fluxes at the PWFS detector.