title: Scaled-model guidelines for formation-flying solar coronagraph missions.
abstract: Stray light suppression is the main concern in designing a solar coronagraph. The main contribution to the stray light for an externally occulted space-borne solar coronagraph is the light diffracted by the occulter and scattered by the optics. It is mandatory to carefully evaluate the diffraction generated by an external occulter and the impact that it has on the stray light signal on the focal plane. The scientific need for observations to cover a large portion of the heliosphere with an inner field of view as close as possible to the photospheric limb supports the ambition of launching formation-flying giant solar coronagraphs. Their dimension prevents the possibility of replicating the flight geometry in a clean laboratory environment, and the strong need for a scaled model is thus envisaged. The problem of scaling a coronagraph has already been faced for exoplanets, for a single point source on axis at infinity. We face the problem here by adopting an original approach and by introducing the scaling of the solar disk as an extended source.
authors.forename: Federico
authors.initials: F
authors.lastname: Landini
authors.forename: Marco
authors.initials: M
authors.lastname: Romoli
authors.forename: Cristian
authors.initials: C
authors.lastname: Baccani
authors.forename: Mauro
authors.initials: M
authors.lastname: Focardi
authors.forename: Maurizio
authors.initials: M
authors.lastname: Pancrazzi
authors.forename: Damien
authors.initials: D
authors.lastname: Galano
authors.forename: Volker
authors.initials: V
authors.lastname: Kirschner