Closed-loop wavefront correction for high-contrast imaging: the 'peek-a-boo' algorithm

摘要

High contrast imaging from space must overcome photon noise of the diffracted star light and scattered light from optical components defects. The very high contrast required (up to 10-10 for terrestrial planets) puts severe requirements on the wavefront control system, as the achievable contrast is limited by the quality of the wavefront. The "Peak-a-boo" correction algorithm, presented here, is a closed loop correction method for the shaped pupil coronagraph to minimize the energy in a pre-defined region in the image where terrestrial planets would be found. The reconstruction part uses three intensity measurements in the image plane with a pinhole added to the shaped pupil for diversity. This method has been shown in simulations to converge to the nominal contrast in 2-3 iterations. In addition, the "peak-a-boo" has shown to be effective in broadband conditions.