In this regard the reported concept is a nulling interferometer designed for work with a single aperture. Two features are specific to our coronagraph, namely achromaticity and close-sensing.
Achromaticity allows flexible choice of a working wavelength and of a large spectral bandwidth.
Close-sensing provides the ability to explore around the central source significantly closer than can be achieved by existing coronographs. The essential limitation regarding detection originates in residual wavefront distortions whose effects are described here using the formalism of adaptive optics. In this paper the principle, the generic set-up and the limitations are briefly recalled. Algebraic derivations regarding the effect of atmospheric seeing and the use of adaptive optics are given. On-going progress in adaptive optics, make it conceivable to reach magnitude differences of 12 under similar conditions.