Authors

Sandrine J Thomas, Amir A. Give’on, Daren Dillon, Bruce Macintosh, Donald Gavel, Remi Soummer

Affiliations

UCO/Lick Observatory JPL Laurence Livermore National Space Telescope Science Institute

Abstract

High contrast imaging is an ongoing theme in the domain of astronomy, both for ground-based and space-based telescopes. Achieving 10^6 − 10^7 contrasts expected with GPI and SPHERE or 10^10 contrast for space projects, requires extreme wavefront correction as well as good coronagraphic systems. We use the Electric Field Conjugation (EFC) as the extreme wavefront correction. EFC is a formalism of the correction problem that computes the actuator commands for the deformable mirror (DM) to correct for both amplitude and phase in a pre-defined region in the final image plane. Already successfully tested for space-based telescopes, we are here adapting this method to ground-based observations. We also use the EFC high contrast solution to record new reference centroids for a Shack-Hartmann wavefront sensor, which in turn can be used to recreate the far-field image. This paper shows results of the first use of the EFC method with an APLC. We achieved 4.10^8 contrast on a [4-9] λ/d square region. We also show how it can be applied to ground based adaptive optics, using Shack-Hartmann wavefront sensors.