Estimating non-common path aberrations with an adaptive coronagraph

Context. The focal-plane contrast of exoplanet imagers is affected by non-common path aberrations (NCPAs) that the adaptive optics system cannot correct for because they occur after wavefront has been measured. NCPA estimation commonly based on long-exposure science image. Phase retrieval algorithms are often used, and mostly assume residual phase error right averaged over integration time zero. This assumption not always correct, instance when controlling to maximize at location an exoplanet, say in coronagraph. For such cases, we present a method calculate using information derived from sensor (WFS) data Aims. We aim accurately estimate presence (residual) atmospheric turbulence with nonzero average wavefront. then take into account coronagraph controller achieve higher contrast. Methods. WFS measures throughout combine recorded phases remove effects Point Spread Function (PSF) averaging time. Then applying phase-diversity-based algorithm resulting images. Our currently limited pupil-plane coronagraphs. Results. able recover setting 0.01 radian RMS residuals approximately 0.4 RMS. When accounted contrast-control scheme, correction leads order magnitude improvement 50% increase Strehl ratio, numerical simulations.