A cm1PARISON OF THE DETERMINATION OF CLOSL'RE PHASE IN OPTICAL :NTERFEROMETRY WITH FL1.LY FILLED APERTURES AND NON-REDUNDANT APERTURE MASKS

The recent successes in diffraction limited optical imaging from · the ground by Weigelt et al. <1986> and Baldwin et al. <1986> rely on the use of the closure phase i.e. the sum of the visibility phases around a closed loop of baselines . The closure phase has been used for the last dozen years in VLBI for making diffraction limited images in situations where the observed phase of the the incoming wavefront is badly corrupted by propagation and instrumental effects .