Design optimization of the forward baffle of the ESA Vigil heliospheric imager

Vigil is an upcoming ESA satellite mission designed to monitor space weather, with a particular focus on the solar corona and the interplanetary space between the Sun and Earth. This paper introduces the basic design of a Forward Baffle (FB), currently being developed for the Heliospheric Imager (HI) instrument included in the Vigil spacecraft’s payload to observe very faint coronal mass ejections (CME) across a wide field of view. The presented wide-angle FB is one of the key optical components of the HI designed to suppress direct stray-light from the solar disk. It consists of a multi-stage diffractive vanes (MSDV) module involving multi-wedge structures with a highreflectivity surface coating and a dedicated thermo-mechanically stabilized FB supporting assembly providing the required spatial and angular position of the MSDV relative to two observation cameras of the HI instrument. The FB supporting assembly is designed to meet the accommodation constraints of the HI instrument.