Optical design of the Lyman alpha coronagraph for the LYOT microsatellite

The LYOT (LYman Orbiting Telescope) solar mission (proposed for a CNES micro-satellite) is composed of a disk imager and a coronagraph, both working at Lyman-α (121.6 nm). The coronagraph is internally occulted and all-reflective with a field-of-view of 1.2 R up to 2.5 R and high spatial resolution (2 pixels) amounts to 5 arcsec. The optical design is driven by the requirement to use a superpolished spherical mirror to minimize the scattered light into the instrument. The LYOT mission will observe the Lyman-α corona at high cadence (1 image/5 minutes) over a period of two years.