  In this paper are reviewed various designs of advanced, multi-aperture
optical systems dedicated to high angular resolution imaging or to the
detection of exo-planets by nulling interferometry. A simple Fourier optics
formalism applicable to both imaging arrays and nulling interferometers is
presented, allowing to derive their basic theoretical relationships as
convolution or cross correlation products suitable for fast and accurate
computation. Several unusual designs, such as a super-resolving telescope
utilizing a mosaicking observation procedure or a free-flying, axially
recombined interferometer are examined, and their performance in terms of
imaging and nulling capacity are assessed. In all considered cases, it is found
that the limiting parameter is the diameter of the individual telescopes. The
entire study is only valid in the frame of first-order geometrical optics and
scalar diffraction theory. Furthermore, it is assumed that all entrance
sub-apertures are optically conjugated with their associated exit pupils, a
particularity inducing an instrumental behavior comparable with those of
diffraction gratings.
