High contrast spectroscopy testbed (HCST): experimental results with an apodized vortex coronagraph

A. Bertrou-Cantou; J. Llop-Sayson; J. Liberman; D. Mawet; J. G. Hagopian; G. Ruane; A. J. Eldorado Riggs; E. Serabyn

doi:10.1117/12.2677902

5 October 2023 High contrast spectroscopy testbed (HCST): experimental results with an apodized vortex coronagraph

A. Bertrou-Cantou, J. Llop-Sayson, J. Liberman, D. Mawet, J. G. Hagopian, G. Ruane, A. J. Eldorado Riggs, E. Serabyn

Proceedings Volume 12680, Techniques and Instrumentation for Detection of Exoplanets XI; 126801B (2023) https://doi.org/10.1117/12.2677902
Event: SPIE Optical Engineering + Applications, 2023, San Diego, California, United States

Abstract

The High Contrast Spectroscopy Testbed (HCST) in the Exoplanet Technology laboratory (ETlab) at Caltech is an in-air testbed hosting all key components necessary to demonstrate coronagraphic performance in broadband light with the vortex coronagraph. The testbed was recently upgraded with the aim of closing the remaining technological gaps in terms of pupil segmentation and to demonstrate our main objective: achieving 10⁻⁸contrast in broadband light. As part of the HCST redesign, a new apodizer has been manufactured using carbon nanotubes acting as microdots to encode a grayscale pattern. This technology presents a very low reflectance conducive to highly efficient amplitude apodization. We demonstrate raw contrasts of 1 × 10⁻⁸ with the apodized vortex coronagraph, both in narrowband and broadband light (10% bandwidth), and with the use of wavefront control. The use of an apodizer enables to deal with the diffraction caused by the segment gaps and successfully eliminates this source of starlight leakage for the vortex coronagraph to the 10⁻⁸ level.

Conference Presentation

Citation Download Citation

A. Bertrou-Cantou, J. Llop-Sayson, J. Liberman, D. Mawet, J. G. Hagopian, G. Ruane, A. J. Eldorado Riggs, and E. Serabyn "High contrast spectroscopy testbed (HCST): experimental results with an apodized vortex coronagraph", Proc. SPIE 12680, Techniques and Instrumentation for Detection of Exoplanets XI, 126801B (5 October 2023); https://doi.org/10.1117/12.2677902

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