Wide field performance of a phased array telescope

Abstract

A phased array telescope is an array of optical telescopes whose images are coherently combined so as to achieve the resolution of a single but much larger telescope. Phased array telescopes deliver the resolution of very large telescopes without the difficulties and expenses associated with very large optics. To achieve this resolution, a wide field of view (FOV) phased array imaging system must accurately control phase and must superimpose the images from all telescopes to within a fraction of a resolution element over the whole FOV simultaneously. We built a test bed called the Multipurpose Multiple Telescope Testbed (MMTT). It consists of four 20-cm-aperture telescopes phased together with a ± 15-arcmin FOV. It has no mount and is designed for laboratory use only. We present a brief description of the MMTT and then describe performance tests and results. The phasing and image superpositioning accuracy of the array were measured using star tests. Several of the resulting point spread functions were recorded simultaneously at three different field angles to determine the wide FOV performance of this phased array. These images were analyzed and compared to theoretical predictions.