The enduring technique of aperture masking interferometry, now more than 150 years old, is still widely practised today for it opens a window of high angular resolution astronomy that remains difficult to access by any competing technology. However, the requirement to apodise the pupil into a non-redundant array dramatically limits the throughput, typically to 10% or less. This in turn has a dramatic impact on the sensitivity so that only bright classes of science have been targeted. This paper presents “Jewel masks”, a novel technology that leverages the gains in signal fidelity conferred by non-redundant Fizeau beam combination without the sensitivity penalty incurred by traditional aperture masks. Our approach fragments the pupil with a set of phase wedges, producing several sets of sparse-array tilings. After extensive searching, solutions were found where all individual sets are fully non-redundant. Each set is assigned a common phase wedge which diverts that pattern onto a defined region of the sensor. We describe transmissive and reflective implementations, as well as a case study of a VAMPIRES mask with realistic fabrication errors.
|