Asgard/NOTT: water vapor and CO$_2$ atmospheric dispersion compensation system
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| Main Authors: | , , , , , , , , , , |
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| Format: | Preprint |
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2024
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| _version_ | 1866913600415727616 |
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| author | Laugier, Romain Defrère, Denis Ireland, Michael Garreau, Germain Absil, Olivier Matter, Alexis Petrov, Romain Berio, Philippe Tuthill, Peter Martinod, Marc-Antoine Labadie, Lucas |
| author_facet | Laugier, Romain Defrère, Denis Ireland, Michael Garreau, Germain Absil, Olivier Matter, Alexis Petrov, Romain Berio, Philippe Tuthill, Peter Martinod, Marc-Antoine Labadie, Lucas |
| contents | To leverage the angular resolution of interferometry at high contrast, one must employ specialized beam-combiners called interferometric nullers. Nullers discard part of the astrophysical information to optimize the recording of light present in the dark fringe of the central source. Asgard/NOTT will deploy a beam-combination scheme offering good instrumental noise rejection when phased appropriately, but for which information is degenerate on the outputs, prompting a dedicated tuning strategy using the science detector. The dispersive effect of water vapor can be corrected with prisms forming a variable thickness of glass. But observations in the L band suffer from an additional and important chromatic effect due to longitudinal atmospheric dispersion coming from a resonance of CO2 at 4.3 micron. To compensate for this effect efficiently, a novel type of compensation device will be deployed leveraging a gas cell of variable length at ambient pressure. After reviewing the impact of water vapor and CO2, we present the design of this atmospheric dispersion compensation device and describe a strategy to maintain this tuning on-sky. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2407_17177 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Asgard/NOTT: water vapor and CO$_2$ atmospheric dispersion compensation system Laugier, Romain Defrère, Denis Ireland, Michael Garreau, Germain Absil, Olivier Matter, Alexis Petrov, Romain Berio, Philippe Tuthill, Peter Martinod, Marc-Antoine Labadie, Lucas Instrumentation and Methods for Astrophysics To leverage the angular resolution of interferometry at high contrast, one must employ specialized beam-combiners called interferometric nullers. Nullers discard part of the astrophysical information to optimize the recording of light present in the dark fringe of the central source. Asgard/NOTT will deploy a beam-combination scheme offering good instrumental noise rejection when phased appropriately, but for which information is degenerate on the outputs, prompting a dedicated tuning strategy using the science detector. The dispersive effect of water vapor can be corrected with prisms forming a variable thickness of glass. But observations in the L band suffer from an additional and important chromatic effect due to longitudinal atmospheric dispersion coming from a resonance of CO2 at 4.3 micron. To compensate for this effect efficiently, a novel type of compensation device will be deployed leveraging a gas cell of variable length at ambient pressure. After reviewing the impact of water vapor and CO2, we present the design of this atmospheric dispersion compensation device and describe a strategy to maintain this tuning on-sky. |
| title | Asgard/NOTT: water vapor and CO$_2$ atmospheric dispersion compensation system |
| topic | Instrumentation and Methods for Astrophysics |
| url | https://arxiv.org/abs/2407.17177 |