Optimizing the Optical Calibration Performance of a Multi-Object Adaptive Optics Instrument
Date
2013-12-17
Authors
Pham, Laurie Nhu An
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Abstract
Multi-Object Adaptive Optics (MOAO) is an adaptive optics technique being developed for Extremely Large Telescopes that will allow simultaneous observation of approximately 20 targets in a several arc-minute field of regard. Raven is an MOAO pathfinder developed by the Adaptive Optics Laboratory of the University of Victoria, in collaboration with the National Research Council of Canada and the Subaru Telescope. It will be the first MOAO instrument on a 8-m class telescope, will demonstrate that MOAO technical challenges such as open-loop control and calibration are achievable on-sky and will deliver science results using three natural guide stars and two science arms on ∼ 3.5′ field-of-regard. The open-loop approach makes the need for calibration even more crucial.
An important part of the calibration process resides in the misregistration of the wavefront sensors (WFSs) with the deformable mirrors (DMs) because the sensing elements are located before the correcting ones. This problem is solved using a cal- ibration DM seen by all WFSs in the system that permits the open-loop WFS to be registered to the science DMs. The method developed in this thesis registers the position of the DM actuators to the WFSs and gives misregistration values. These results are then used to better align the instrument, to have a better knowledge of the positions of the different optical components and generate new ways to perform the AO correction. Using the registration parameters results, synthetic interaction matrices are created in order to improve the AO correction. Calibration tests are also presented in this thesis. They show complementary tests to the expected requirements to expand the knowledge of the calibration unit behaviour.
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Keywords
adaptive optics, astronomy, optical instrument, telescope, mechanical engineering