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Proceedings Paper

FIB machining of occulting masks for imaging of extrasolar planets
Author(s): Shilpa N. Raja; Michael J. Aziz; James W. Foley; Volker Tolls
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Paper Abstract

We are developing the ability for Focused Ion Beam (FIB) machining of occulting masks for use in coronagraphs. These masks will be used as soft-edged Lyot stops to suppress light from stars and allow direct imaging of extrasolar planets. The FIB approach is attractive because it has the potential for higher precision than mechanical machining and for larger volumes than electron-beam lithography. The mask fabrication process is trifold: 1) a transparent material-currently, poly(methyl methacrylate) (PMMA)-is doped with dyes; 2) the mask shape is FIB milled into the material; and 3) the mask is coated with another layer of index-matching transparent absorber. Using a Zeiss NVision 40 FIB system, we have fabricated conical-shaped masks of various slopes in dye-doped PMMA. Inherent in this process is the advantage of control of the features through programming the ion beam track. We have also optically characterized these masks as well as the dye-doped absorbing material. We have found that the dye-doped PMMA has a very high absorbance, >1 OD.

Paper Details

Date Published: 19 August 2009
PDF: 7 pages
Proc. SPIE 7440, Techniques and Instrumentation for Detection of Exoplanets IV, 744018 (19 August 2009); doi: 10.1117/12.828515
Show Author Affiliations
Shilpa N. Raja, Harvard Univ. (United States)
Michael J. Aziz, Harvard Univ. (United States)
James W. Foley, Rowland Institute at Harvard (United States)
Volker Tolls, Harvard-Smithsonian Ctr. for Astrophysics (United States)

Published in SPIE Proceedings Vol. 7440:
Techniques and Instrumentation for Detection of Exoplanets IV
Stuart B. Shaklan, Editor(s)

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