Simulations of stray light from the surface scattering of the Solar Corona Imager primary mirror

摘要

The Solar Corona Imager is an internally occulted coronagraph on board the ASO-S mission, which has the advantage of imaging the inner corona in H I Lyman-α (Lyα) and white-light (WL) wavebands. However, scattering of solar disk light by the primary mirror (Ml) becomes the main source of stray light. To study the methods of stray light suppression, three scattering models are used to model Ml scattering in Zemax OpticStudio. The ratio of coronal emission to predicted stray light decrease along field of view in both channels. The stray light in Ly αchannel is generally lower than coronal emission, but the stray light in WL channel tends to be one order of magnitude higher than coronal signal at 2.5 R⊙. Optimized parameter combinations that suppress the stray light to required level are obtained, which put some limitations on the Ml manufacture. Besides, K-correlation model is recommended to simulate surface scattering.