Novel Space Coronagraphs: METIS, a flexible optical design for multi-wavelength imaging and spectrography

This presentation outlines a general optical design for coronagraphs working in both the visible-light (VL) and UV/EUV wavelength ranges by combining the use of reflective, multilayer-coated or interference-coated optics with Lyot stops. This design has been successfully applied to a sub-orbital coronagraph. Another version of this novel design for visible-light/EUV coronagraphs uses an inverted-occultation design in order to minimize the solar flux entering the instrument. This design has been used for the coronagraph - METIS - on board the ESA Solar Orbital mission. The current optical configuration of METIS adopted for the Solar Orbiter mission includes Visible-light and UV imaging. However, the innovative inverted-occultation concept is flexible enough that it can also accommodate a EUV spectrograph maintaining the same basic optical layout. The paper also describes the potential capabilities of the inverted-occulter coronagraph as a VL/UV imager and EUV spectrograph for future solar missions.