ELT LGS-AO: Optimizing the LGS return flux


D.Bonaccini Calia, I.Guidolin, S.Lewis, W.Hackenberg, R.Holzlohner, G.Lombardi


European Southern Observatory (ESO)


For the ELTs the use of AO with multiple sodium LGS will be routine. We think it is important to study the LGS generation in order to optimize the LGS-AO systems. It is in this context that we are working on the understanding and optimization of the LGS parameters. In this paper we report on our LGS return flux studies, aimed at identifying the optimal laser formats for CW and pulsed lasers. We have done recently numerical simulations on the LGS return flux for different laser formats, solving the Bloch equations for the interaction of the mesospheric sodium atoms with the laser radiation, which need now to be validated. We will report on the ESO Wendelstein transportable 20W LGS unit system, recently built and tested to make systematic field studies on the LGS, which will be described including the validation of the return flux simulations. The first experimental results are due this summer and will be reported as available.

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