Abstract
The detection and characterization of extra-solar planets is a major theme driving modern astronomy. Direct imaging of exoplanets allows access to a parameter space complementary to other detection methods, and potentially the characterization of exoplanetary atmospheres and surfaces. However achieving the required levels of performance with direct imaging from ground-based telescopes (subject to Earth's turbulent atmosphere) has been extremely challenging. Here we demonstrate a new generation of photonic pupil-remapping devices which build upon the Dragonfly instrument, a high contrast waveguide-based interferometer. This new generation overcomes problems caused by interference from unguided light and low throughput. Closure phase measurement scatter of only ∼ 0.2° has been achieved, with waveguide throughputs of > 70%. This translates to a maximum contrast-ratio sensitivity between star and planet at 1λ/D (1σ detection) of 5.3 × 10(-4) (with a conventional adaptive-optics system) or 1.8 × 10(-4) (with 'extreme-AO'), improving even further when random error is minimized by averaging over multiple exposures. This is an order of magnitude beyond conventional pupil-segmenting interferometry techniques (such as aperture masking), allowing a previously inaccessible part of the star to planet contrast-separation parameter space to be explored.
Highlights
Ever since the beginning of the modern era of extra-solar planet discovery [1], the detection and characterisation of exoplanets has been one of the most active areas in contemporary astronomy
This observable has been the key to successful high resolution, high contrast studies with conventional aperturemasking interferometry [15], and becomes significantly more powerful when implemented with Dragonfly
The reflected beam is re-imaged by beam-reducing optics onto a hexagonal microlens array (MLA) with 30 μm pitch, such that there is a one-toone correspondence between MEMS mirror segments and individual MLA lenslets
Summary
Ever since the beginning of the modern era of extra-solar planet discovery [1], the detection and characterisation of exoplanets has been one of the most active areas in contemporary astronomy. Coronagraphs fed by AO systems represent the most developed class of high contrast imaging techniques, and they have demonstrated exceptionally high contrast at large separation, performance is more limited at spatial scales of order 1λ /D (corresponding to the Earth-Sun separation at a distance of ∼30 parsecs), even with the most advanced refinements [4] To some extent this problem of the most productive search space lying within the so-called inner working angle of the coronagraph is inherent to the basic design of the instrument, and in practice is compounded by residual phase-aberrations present in the imaging system (largely from imperfect AO correction). Neither is possible for the case of masking interferometry, which fundamentally limits the precision attainable by this technique
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