Latest Ground Layer Adaptive Optics results and advancements in Laser Tomography implementation at the 6.5m MMT telescope


Eduardo Bendek, Michael Hart, Keith Powell, Vidhya Vaitheeswaran, Don McCarthy, Craig Kulesa


University of Arizona


Laser tomography capability using the Multi Laser Guide Star system is being implemented at the 6.5 m MMT telescope on Mt. Hopkins AZ. The system uses five range gated and dynamically refocused Rayleigh laser beacons to perform the tomographic sampling of the atmosphere. Corrections are then applied to the wavefront using the 336-actuator adaptive secondary mirror of the telescope. We present the latest results obtained using the GLAO mode, using for the first time, a plate scale on our IR science camera that samples the diffraction scale at the Nyquist limit. We find a reduction in the width of the on-axis point-spread function from 1.1” to <0.2” in H band. In addition, progress toward Laser Tomography is presented using an approach in which a minimum mean square reconstructor matrix is computed from simultaneous measurements recorded by the LGS wavefront sensor and a ground-truth NGS sensor. This paper also discusses our approach to estimate the turbulence intensity distribution Cn2, which is essential to our goal to build tomographic reconstructor matrices with an analytic forward model, to be updated on the fly during regular observing.

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