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Proceedings Paper

Performance of an achromatic focal plane mask for exoplanet imaging coronagraphy
Author(s): Kevin Newman; Ruslan Belikov; Eugene Pluzhnik; Kunjithapatham Balasubramanian; Dan Wilson
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Paper Abstract

Coronagraph technology combined with wavefront control is close to achieving the contrast and inner working angle requirements in the lab necessary to observe the faint signal of an Earth-like exoplanet in monochromatic light. An important remaining technological challenge is to achieve high contrast in broadband light. Coronagraph bandwidth is largely limited by chromaticity of the focal plane mask, which is responsible for blocking the stellar PSF. The size of a stellar PSF scales linearly with wavelength; ideally, the size of the focal plane mask would also scale with wavelength. A conventional hard-edge focal plane mask has a fixed size, normally sized for the longest wavelength in the observational band to avoid starlight leakage. The conventional mask is oversized for shorter wavelengths and blocks useful discovery space. Recently we presented a solution to the size chromaticity challenge with a focal plane mask designed to scale its effective size with wavelength. In this paper, we analyze performance of the achromatic size-scaling focal plane mask within a Phase Induced Amplitude Apodization (PIAA) coronagraph. We present results from wavefront control around the achromatic focal plane mask, and demonstrate the size-scaling effect of the mask with wavelength. The edge of the dark zone, and therefore the inner working angle of the coronagraph, scale with wavelength. The achromatic mask enables operation in a wider band of wavelengths compared with a conventional hard-edge occulter.

Paper Details

Date Published: 19 August 2014
PDF: 7 pages
Proc. SPIE 9151, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation, 91515O (19 August 2014); doi: 10.1117/12.2055354
Show Author Affiliations
Kevin Newman, The Univ. of Arizona (United States)
NASA Ames Research Ctr. (United States)
Ruslan Belikov, NASA Ames Research Ctr. (United States)
Eugene Pluzhnik, NASA Ames Research Ctr. (United States)
Kunjithapatham Balasubramanian, Jet Propulsion Lab. (United States)
Dan Wilson, Jet Propulsion Lab. (United States)


Published in SPIE Proceedings Vol. 9151:
Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation
Ramón Navarro; Colin R. Cunningham; Allison A. Barto, Editor(s)

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