SCAO Simulation Results with a Pyramid Sensor on an ELT-like Telescope
Gemini Observatory Southern Operations Center, c/o AURA,
La Serena, Chile
2 European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748, Garching bei Muenchen, Germany
a e-mail: email@example.com
We show the performance derived from simulations of a single-conjugated adaptive optics (SCAO) system for an ELT using the pyramid wavefront sensor (hereafter PWFS). The main objective of this work is to obtain the parameters which optimize the Strehl and characterize the system. Adopting K as the science band, we verify that the overall performance tends to be poorer as the sensing wavelength becomes shorter (as we probed K, J and R bands), the loop gain optimal range is dependent on the singular-value decomposition (SVD) truncation threshold used to build the command matrix, and that a "natural" modulation for the PWFS (i.e. zero modulation) produces in general poorer results when compared to modulated cases, being this especially true for the R-sensing band. Also more modulation is needed as one goes to shorter wavelengths. Comparisons between a scaled-down version of the simulations and those for a 42m telescope are performed. The atmospheric model adopted was always a von Karman with r0=0.13m@500nm and outer-scale L0=25m. The telescope pupil had a central obstruction of 28% and no spiders. The NGS was put on-axis, and diffraction between pyramid imaged pupils taken into account.
© Owned by the authors, published by EDP Sciences, 2010