Demonstrating broadband billion-to-one contrast with the Visible Nulling Coronagraph

Brian A. Hicks; Richard G. Lyon; Peter Petrone III; Ian J. Miller; Matthew R. Bolcar; Mark Clampin; Michael A. Helmbrecht; Udayan Mallik

doi:10.1117/12.2189101

11 September 2015 Demonstrating broadband billion-to-one contrast with the Visible Nulling Coronagraph

Brian A. Hicks, Richard G. Lyon, Peter Petrone III, Ian J. Miller, Matthew R. Bolcar, Mark Clampin, Michael A. Helmbrecht, Udayan Mallik

Author Affiliations +

Proceedings Volume 9605, Techniques and Instrumentation for Detection of Exoplanets VII; 96050K (2015) https://doi.org/10.1117/12.2189101
Event: SPIE Optical Engineering + Applications, 2015, San Diego, California, United States

Abstract

The key to broadband operation of the Visible Nulling Coronagraph (VNC) is achieving a condition of quasi-achromatic destructive interference between combined beams. Here we present efforts towards meeting this goal using Fresnel rhombs in each interferometric arm as orthogonally aligned half wave phase retarders. The milestone goal of the demonstration is to achieve 1 × 10−9 contrast at 2λ/D over a 40 nm bandpass centered at 633 nm. Rhombs have been designed and fabricated, and a multi-step approach to alignment using coarse positioners for each rhomb and pair has been developed to get within range of piezo stages used for fine positioning. The previously demonstrated narrowband VNC sensing and control approach that uses a segmented deformable mirror is being adapted to broadband to include fine positioning of the piezo-mounted rhombs, all demonstrated in a low-pressure environment.

Citation Download Citation

Brian A. Hicks, Richard G. Lyon, Peter Petrone III, Ian J. Miller, Matthew R. Bolcar, Mark Clampin, Michael A. Helmbrecht, and Udayan Mallik "Demonstrating broadband billion-to-one contrast with the Visible Nulling Coronagraph", Proc. SPIE 9605, Techniques and Instrumentation for Detection of Exoplanets VII, 96050K (11 September 2015); https://doi.org/10.1117/12.2189101

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