Super-Resolving Toraldo Pupils for Radio Astronomical Applications: current status and future prospects

More than half a century ago, in 1952, Giuliano Toraldo di Francia suggested
that the resolving power of an optical instrument could be improved using a
filter consisting of finite-width concentric coronae of different amplitude and
phase transmittance, now known as Toraldo Pupils (TPs). The concept of ’super-
resolution’ was born, and in the cur- rent literature it is generally associated
with various meth- ods for improving the angular resolution of an optical imag-
ing system beyond the classical diffraction limit. In the mi- crowave range,
the first successful laboratory test of TPs was performed in 2003. These first
results suggested that TPs could represent a viable approach to achieve super-
resolution in Radio Astronomy. We have therefore started a project devoted
to an exhaustive study of TPs and how they could be implemented on a radio
telescope. In this work we present a summary of the status of this project, and
then we will describe our future plans.