Exoplanet explorer: optical design of a single spacecraft nulling interferometer

The optical design layout of a single-spacecraft nulling interferometer is presented here as part of an ESA-initiated study to explore the design parameters and performance of an interferometric concept based on a single spacecraft with multiple sub-apertures. Launch constraints drive the ray-traced model to cover the entire optical chain, from the telescope entrance to the null output after the recombination scheme. A trade-off among several telescope architectures led to the choice of a compact two-mirror solution consisting of four 2.5m diameter telescopes arranged in a linear configuration with an extended baseline. Optical performance at the null output is evaluated, confirming compatibility with starlight suppression targets and establishing the key figures of merit for the interferometer. This work presents the first integrated optical design of the mission concept, laying the groundwork for future iterations that include mechanical, thermal, and control aspects.