Visible nulling coronagraph testbed results

Richard G. Lyon; Mark Clampin; Robert A. Woodruff; Gopal Vasudevan; Patrick Thompson; Peter Petrone; Timothy Madison; Maxime Rizzo; Gary Melnick; Volker Tolls

doi:10.1117/12.827423

25 August 2009 Visible nulling coronagraph testbed results

Richard G. Lyon, Mark Clampin, Robert A. Woodruff, Gopal Vasudevan, Patrick Thompson, Peter Petrone, Timothy Madison, Maxime Rizzo, Gary Melnick, Volker Tolls

Author Affiliations +

Proceedings Volume 7440, Techniques and Instrumentation for Detection of Exoplanets IV; 744011 (2009) https://doi.org/10.1117/12.827423
Event: SPIE Optical Engineering + Applications, 2009, San Diego, California, United States

Abstract

We report on our recent laboratory results with the NASA/Goddard Space Flight Center (GSFC) Visible Nulling Coronagraph (VNC) testbed. We have experimentally achieved focal plane contrasts of 1 x 10⁸ and approaching 10⁹ at inner working angles of 2 * wavelength/D and 4 * wavelength/D respectively where D is the aperture diameter. The result was obtained using a broadband source with a narrowband spectral filter of width 10 nm centered on 630 nm. To date this is the deepest nulling result with a visible nulling coronagraph yet obtained. Developed also is a Null Control Breadboard (NCB) to assess and quantify MEMS based segmented deformable mirror technology and develop and assess closed-loop null sensing and control algorithm performance from both the pupil and focal planes. We have demonstrated closed-loop control at 27 Hz in the laboratory environment. Efforts are underway to first bring the contrast to > 10⁹ necessary for the direct detection and characterization of jovian (Jupiter-like) and then to > 10¹⁰ necessary for terrestrial (Earth-like) exosolar planets. Short term advancements are expected to both broaden the spectral passband from 10 nm to 100 nm and to increase both the long-term stability to > 2 hours and the extent of the null out to a ~ 10 * wavelength / D via the use of MEMS based segmented deformable mirror technology, a coherent fiber bundle, achromatic phase shifters, all in a vacuum chamber at the GSFC VNC facility. Additionally an extreme stability textbook sized compact VNC is under development.

Citation Download Citation

Richard G. Lyon, Mark Clampin, Robert A. Woodruff, Gopal Vasudevan, Patrick Thompson, Peter Petrone, Timothy Madison, Maxime Rizzo, Gary Melnick, and Volker Tolls "Visible nulling coronagraph testbed results", Proc. SPIE 7440, Techniques and Instrumentation for Detection of Exoplanets IV, 744011 (25 August 2009); https://doi.org/10.1117/12.827423

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