Adaptive Optics for Extremely Large Telescopes 4 – Conference Proceedings

We analyze the altitude distribution of the turbulence outer scale - L0(h) - at Cerro Pachón from Gemini South MCAO (GeMS) loop data. GeMS turbulence profiler is fed with telemetry from their 5 WFSs and from the voltages applied to the deformable mirrors, providing estimations of r0, Cn2(h), wind profile (speed and direction for every layer), isoplanatic angle and the outer scale distribution L0(h). It is shown that this last parameter ranges from less than 1 meter at the ground to more than 50m (the telescope is insensitive to larger cannot detect differences above this value). The technique is based on cross correlations of the pseudo-open-loop slopes that allow to disentangle the multiple constituents of L0.