Design and Implementation of the Tip/Tilt Compensation System for Raven, a Multi-Object Adaptive Optics System




Nash, Reston

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Multi-Object Adaptive Optics promises to be a useful tool for the upcoming class of Extremely Large Telescopes. Like current adaptive optics systems, MOAO systems compensate optical aberrations caused by atmospheric turbulence, but with the added benefit of being able to compensate multiple portions of a telescope’s field at the same time. To ensure the success of the eventual MOAO systems built for the ELTs, several demonstrator instruments have been designed and tested on current telescopes. Raven is one of these demonstrators, designed by the University of Victoria Adaptive Optics Lab for the Subaru 8.2 meter telescope to feed the InfraRed Camera and Spectrograph. Raven corrects the light of two science targets using wavefront information from three natural guide stars, and a single laser guide star. The topic of this thesis is the design and implementation of Raven’s tip/tilt compensation system, used to stabilize the output image positions on IRCS’s 0.140” slit. Tip/tilt correction of the science targets is done using a combination of motorized pick-off arms, piezoelectric tip/tilt platforms, and deformable mirrors. Through digital filtering and calibration, it is shown that these actuators are able to collectively keep the output science images stationary during simulated laboratory observations. A performance reduction due to residual tip/tilt errors is expected to be less than 5%. Raven goes on-sky in mid-2014, and it will be the first MOAO instrument to attempt scientific observations.



Adaptive Optics, ELT, Plate Scale Modes, Tip/Tilt Tracking, Subaru Telescope