2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/10130Recent adaptive optics systems in astronomy achieve high-angular resolution. With the extreme stability of the images, detection at very low fluxes can be reached using a coronograph at the diffraction limit of the telescopes. This paper is an overview of the issues of stellar coronography used at the diffraction limit. Image formation through such a system is illustrated by numerical simulations. The description of a coronograph implemented on the VLT adaptive optics prototype, COME-ON, is presented as well as the first observations.23 pages including figures and tables, uuencoded gz-compressed postscriptAstrophysicstext