19 August 2016 A conceptual scheme for cophasing across gaps in segmented pupils with a laser guide star Fizeau interferometer
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Finding and maintaining an accurate cophasing solution for the large primary mirrors which comprise the coming generation of Extremely Large Telescopes has required a significant technological development effort that is still ongoing. Mirrors based on an assembly of a few large segments, such as the Giant Magellan Telescope (GMT – under construction) and the Large Binocular Telescope (LBT – operational) face a particular challenge: elements must be cophased across a gaps ranging from tens of centimeters to meters. Although it is widely believed that laser guide stars are not useful for this specific application, this paper advances a new concept that challenges this orthodoxy. By projecting a Fizeau interference pattern into the sky, and analyzing the form of the backscattered image, it is shown that at least in principle it is possible to cophase across arbitrary gaps.
© (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Peter Tuthill, "A conceptual scheme for cophasing across gaps in segmented pupils with a laser guide star Fizeau interferometer", Proc. SPIE 9907, Optical and Infrared Interferometry and Imaging V, 99070E (19 August 2016); doi: 10.1117/12.2232385; https://doi.org/10.1117/12.2232385


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