Meta-lenslet array for laser guide star anamorphic compression

Josephine Munro; Sarah E. Dean; Neuton Li; Israel J. Vaughn; Andrew W. Kruse; Tony Travouillon; Dragomir N. Neshev; Robert Sharp; Andrey A. Sukhorukov

doi:10.1117/12.3022233

6 June 2024 Meta-lenslet array for laser guide star anamorphic compression

Josephine Munro, Sarah E. Dean, Neuton Li, Israel J. Vaughn, Andrew W. Kruse, Tony Travouillon, Dragomir N. Neshev, Robert Sharp, Andrey A. Sukhorukov

Author Affiliations +

Proceedings Volume PC12990, Metamaterials XIV; PC1299022 (2024) https://doi.org/10.1117/12.3022233
Event: SPIE Photonics Europe, 2024, Strasbourg, France

Conference Poster

Abstract

The Giant Magellan Telescope will employ laser tomography adaptive optics, using laser guide stars to measure and correct wavefront distortions with a high sky coverage compared to natural guide stars. A laser guide star is the resonance fluorescence induced by a launch laser propagating through a column of the atmospheric sodium layer, with narrowband emission at a 589nm wavelength. The column shape results in the laser guide star having observable elongation depending on perspective. Shack-Hartmann wavefront sensing remains challenging as the elongated axis of a subaperture focal spot can be as large as 10-14''. Currently, detectors with a large number of pixels are used to compromise between sensitivity and accuracy. We propose a novel approach based on a metasurface lenslet array, where each subaperture has a custom anamorphic ratio and orientation. Two metasurfaces with sub-wavelength-thick nanopatterned layers of TiO2 separated by a 6.5mm air gap accommodate a fixed focal length of 8mm and anamorphic ratios up to 1:10, as confirmed by Optics Studio simulations. We identify the experimentally feasible metasurface design suitable for the established nanofabrication approaches.

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Josephine Munro, Sarah E. Dean, Neuton Li, Israel J. Vaughn, Andrew W. Kruse, Tony Travouillon, Dragomir N. Neshev, Robert Sharp, and Andrey A. Sukhorukov "Meta-lenslet array for laser guide star anamorphic compression", Proc. SPIE PC12990, Metamaterials XIV, PC1299022 (6 June 2024); https://doi.org/10.1117/12.3022233

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