Array designs for imaging

Summary form only given. Two techniques have been used to design telescope arrays for imaging applications. The first technique is applicable to arrays with a relatively small (~10), number of apertures and is essentially an exhaustive search with a simple inline test that allows the search space to be pruned by an order of magnitude. In the second technique, arrays of a large number of apertures are designed by combining the results from several arrays with fewer apertures. The criteria is that the best array would maximize the distance from the origin to the position of the first zero in the transfer function (TF). This criterion has been selected to accommodate reconstruction of image phases from phase-difference averages, a process that is sensitive to zeros in the TF. For telescopes with a large number of individually steerable mirrors, the dominant cost moves away from the fabrication of a mirror and towards the cost of beam combination systems and civil engineering. In order to reduce these costs, a fractal-based approach that encourages modular and replicated subsystems has been adopted