Roman coronagraph instrument optical design description

The coronagraph instrument for the Nancy Grace Roman Space Telescope is a complex instrument developed to directly image an exoplanet orbiting a nearby star. To do so, the light from the host star must be blocked to reveal the light from the planet. To accomplish this task, the instrument leverages many key technologies including hybrid-Lyot coronagraphs, shaped-pupil coronagraphs, electric field conjugation, Zernike wavefront sensing, deformable mirrors, precision alignment mechanisms, and precision fabrication of masks based on the development of microdevices. This large, baby grand piano-sized instrument has been delivered to the Roman Payload for integration. The flight instrument optical subsystem was fully aligned and tested prior to delivery. Besides the successful alignment of the optical subsystem, a few issues involving optical elements were revealed and addressed during the integration and test process. We present the final optical design and layout of the instrument, discuss key performance metrics, and discuss issues and lessons learned.