High-Contrast Aperture Masking Interferometry Predicts 10x Contrast Gain Inside 2 λ/D for Close Companions

The arXiv preprint outlines a hybrid architecture that places a non-redundant mask downstream of a coronagraph to suppress on-axis starlight while preserving interferometric baselines. Preliminary modeling shows that the combined system can reach contrasts of 10^-5 to 10^-6 at 0.5–1.5 λ/D under photon-limited conditions, exceeding standard NRM performance by roughly an order of magnitude. Wavefront stability requirements are estimated at 10–20 nm rms over 10-second integrations, a threshold already demonstrated on current extreme-AO systems at Keck and VLT.

Existing high-contrast surveys using SPHERE, GPI, and JWST NIRCam coronagraphs routinely exclude the inner 2 λ/D region; this gap has left most temperate rocky planets around nearby M dwarfs inaccessible to direct imaging. The new approach re-opens that zone without requiring larger apertures or space-based platforms. It also inherits NRM’s model-independent closure-phase observables, reducing sensitivity to residual speckle noise that limits kernel-phase or reference-differential imaging inside the control radius.

The study remains purely theoretical; no on-sky data or end-to-end simulations with realistic detector noise and segment phasing errors are presented. A next-step demonstration on an 8-m telescope with an existing coronagraph and mask would falsify or confirm the predicted contrast floor within 18 months. If achieved, the technique could be retrofitted to ELT first-light instruments and inform the design of future space coronagraphs targeting exo-Earths.