A new interferometer architecture combining nulling with phase closure measurements

TL;DR

This paper proposes a novel interferometer design that combines nulling and phase closure techniques using integrated optics to improve direct exoplanet imaging by mitigating photon noise and optical aberrations.

Contribution

It introduces a new optical architecture that synthesizes nulling interferometry with closure phase measurements within a single integrated device.

Findings

The proposed design can achieve high dynamic range limited by readout or photon noise.

It is optimal for space-based or bright star ground-based observations.

The architecture leverages integrated optics and photonics technology.

Abstract

Imaging the direct light signal from a faint exoplanet against the overwhelming glare of its host star presents one of the fundamental challenges to modern astronomical instrumentation. Achieving sufficient signal-to-noise for detection by direct imaging is limited by three basic physical processes: aberration of the wavefronts (both instrumental and atmospheric), photon noise, and detector noise. In this paper, we advance a novel optical setup which synthesizes the advantages of two different techniques: nulling interferometry to mitigate photon noise, and closure phase to combat optical aberrations. Our design, which employs technology from integrated optics and photonics, is intended to combine the advantageous aspects of both a coronagraph and a non-redundant interferometer inside a single optical device. We show that such an instrument would have a dynamic range limited either by i) the readout noise (if perfect co-phasing), or ii) the photon noise due to stellar flux leakage (in the case of imperfect nulling). This concept is optimal when the readout noise is not the main limitation, ie, for space interferometry or for ground based observations of bright stellar hosts (apparent magnitude brighter than 10).