  We report on the Achromatic Interfero Coronagraph, a focal imaging device
which aims at rejecting the energy contribution of a point-like source set
on-axis, so as to make detectable its angularly-close environment (applicable
to stellar environment: circumstellar matter, faint companions, planetary
systems, but also conceivably to Active Galatic Nucleii and multiple
asteroids). With AIC, starlight rejection is based on destructive interference,
which allows exploration of the star's neighbouring at angular resolution
better than the diffraction limit of the hosting telescope. Thanks to the focus
crossing property of light, rejection is achromatic thus yielding a large
spectral bandwidth of work. Descriptions and comments are given regarding the
principle, the device itself, the constraints and limitations, and the
theoretical performance. Results are presented which demonstrate the
close-sensing capability and which show images of a companion obtained in
laboratory and 'on the sky' as well. A short pictorial description of
alternative AIC concepts, CIAXE and Open-Air CIAXE, currently under study, is
given.
