| タイトル | Demonstrating Broadband Billion-to-One Contrast with the Visible Nulling Coronagraph |
| 著者（英） | Bolcar, Matthew R.; Helmbrecht, Michael A.; Miller, Ian J.; Petrone, Peter, III; Mallik, Udayan; Hicks, Brian A.; Lyon, Richard G.; Clampin, Mark |
| 著者所属（英） | NASA Goddard Space Flight Center |
| 発行日 | 2015-09-11 |
| 言語 | eng |
| 内容記述 | 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 1 109 contrast at 2/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. |
| NASA分類 | Instrumentation and Photography |
| レポートNO | GSFC-E-DAA-TN35251 |
| 権利 | Copyright |
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