"We propose to develop high contrast coronagraphic techniques for segmented telescopes, providing an integrated solution for wavefront control and starlight suppression on complex aperture geometries. Developing this technology will enable direct imaging of exoplanets from space with significant cost savings relative to monolithic mirrors.
Searching for nearby habitable worlds with direct imaging is one of the top scientific priorities established by the Astro2010 Decadal Survey. Achieving this ambitious goal will require 1010 contrast on a telescope large enough to provide angular resolution and sensitivity to planets around a significant sample of nearby stars. Lightweight segmented mirror technology allows larger diameter optics to fit in any given launch vehicle as compared to monolithic mirrors, making it a compelling option for future space telescopes. But until recently, it was believed that internal coronagraphs were incapable of yielding very high contrast on segmented telescopes.
Recent developments now show that there is in fact a clear path to high contrast coronagraphy on segmented apertures. The key advances are (1) the demonstration of precision wavefront shaping with amplitude control using multiple deformable mirrors, and (2) improvements in coronagraph mask design that dramatically reduce transmission of segment-gap-scattered light.
We propose a plan that will mature these technologies for coronagraphy with on-axis segmented mirror telescopes to TRL 4 by mid-decade with the following elements:
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Numerical studies for coronagraph optimization and wavefront shaping to yield high-contrast point spread function dark zones.
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Precision segment phasing concepts and algorithms that will improve the state of the art by one order of magnitude, and will be applicable to any segmented telescope.
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A system-level demonstration integrating segment precision phasing, wavefront control and shaping, together with advanced coronagraphy.
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