Aragoscope

An Aragoscope is a telescope design based on diffraction around the edge of an occluding disc, named after French scientist François Arago.

Concept
The light diffracted around the edge of a perfectly circular occluder interferes constructively at the central axis, and the resolution at that point would be equal to the resolution of conventional lens with the same size as the occluder. Only light intensity would be lower. On this basis it would be possible to create a telescope by placing a suitable disc in space accompanied by a separate telescope some distance away along its axis. This concept has been explored by NASA and received Phase One funding in June 2014 by the NASA Innovative Advanced Concepts (NIAC) program.

It is important to note that this is a very different approach from that taken by another NASA project, the New Worlds Mission, which aims to use an occluder with "petals", otherwise known as a starshade, specifically designed to avoid diffraction onto the central axis.