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Future searches for biomarkers on habitable exoplanets will rely on telescopeinstruments that achieve extremely high contrast at small planet-to-starangular separations. Coronagraphy is a promising starlight suppressiontechnique, providing excellent contrast and throughput for off-axis sources onclear apertures. However, the complexity of space- and ground-based telescopeapertures goes on increasing over time, owing to the combination of primarymirror segmentation, secondary mirror, and support structures. Thesediscontinuities in the telescope aperture limit the coronagraph performance. Inthis paper, we present ACAD-OSM, a novel active method to correct for thediffractive effects of aperture discontinuities in the final image plane of acoronagraph. Active methods use one or several deformable mirrors that arecontrolled with an interaction matrix to correct for the aberrations in thepupil. However, they are often limited by the amount of aberrations introducedby aperture discontinuities. This algorithm relies on the recalibration of theinteraction matrix during the correction process to overcome this limitation.We first describe the ACAD-OSM technique and compare it to the previous activemethods for the correction of aperture discontinuities. We then show itsperformance in terms of contrast and off-axis throughput for static aperturediscontinuities (segmentation, struts) and for some aberrations evolving overthe life of the instrument (residual phase aberrations, artifacts in theaperture, misalignments in the coronagraph design). This technique can nowobtain the earth-like planet detection threshold of 10^(-10) contrast on anygiven aperture over at least a 10% spectral bandwidth, with several coronagraphdesigns.

Active correction of aperture discontinuities - optimized stroke minimization I: a new adaptive interaction matrix algorithm