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Proceedings Paper

Demonstration of high contrast in 10% broadband light with the shaped pupil coronagraph
Author(s): Ruslan Belikov; Amir Give'on; Brian Kern; Eric Cady; Michael Carr; Stuart Shaklan; Kunjithapatham Balasubramanian; Victor White; Pierre Echternach; Matt Dickie; John Trauger; Andreas Kuhnert; N. Jeremy Kasdin
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Paper Abstract

The Shaped Pupil Coronagraph (SPC) is a high-contrast imaging system pioneered at Princeton for detection of extra-solar earthlike planets. It is designed to achieve 10-10 contrast at an inner working angle of 4λ/D in broadband light. A critical requirement in attaining this contrast level in practice is the ability to control wavefront phase and amplitude aberrations to at least λ/104 in rms phase and 1/1000 rms amplitude, respectively. Furthermore, this has to be maintained over a large spectral band. The High Contrast Imaging Testbed (HCIT) at the Jet Propulsion Lab (JPL) is a state-of-the-art facility for studying such high contrast imaging systems and wavefront control methods. It consists of a vacuum chamber containing a configurable coronagraph setup with a Xinetics deformable mirror. Previously, we demonstrated 4x10-8 contrast with the SPC at HCIT in 10% broadband light. The limiting factors were subsequently identified as (1) manufacturing defects due to minimal feature size constraints on our shaped pupil masks and (2) the inefficiency of the wavefront correction algorithm we used (classical speckle nulling) to correct for these defects. In this paper, we demonstrate the solutions to both of these problems. In particular, we present a method to design masks with practical minimal feature sizes and show new manufactured masks with few defects. These masks were installed at HCIT and tested using more sophisticated wavefront control algorithms based on energy minimization of light in the dark zone. We present the results of these experiments, notably a record 2.4×10-9 contrast in 10% broadband light.

Paper Details

Date Published: 19 September 2007
PDF: 11 pages
Proc. SPIE 6693, Techniques and Instrumentation for Detection of Exoplanets III, 66930Y (19 September 2007); doi: 10.1117/12.734976
Show Author Affiliations
Ruslan Belikov, Princeton Univ. (United States)
Amir Give'on, Jet Propulsion Lab. (United States)
Brian Kern, Jet Propulsion Lab. (United States)
Eric Cady, Princeton Univ. (United States)
Michael Carr, Princeton Univ. (United States)
Stuart Shaklan, Jet Propulsion Lab. (United States)
Kunjithapatham Balasubramanian, Jet Propulsion Lab. (United States)
Victor White, Jet Propulsion Lab. (United States)
Pierre Echternach, Jet Propulsion Lab. (United States)
Matt Dickie, Jet Propulsion Lab. (United States)
John Trauger, Jet Propulsion Lab. (United States)
Andreas Kuhnert, Jet Propulsion Lab. (United States)
N. Jeremy Kasdin, Princeton Univ. (United States)

Published in SPIE Proceedings Vol. 6693:
Techniques and Instrumentation for Detection of Exoplanets III
Daniel R. Coulter, Editor(s)

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