日冕仪是在像面人工制造日全食影像的日冕观测仪器，其具备的杂光遮拦结构可使得日冕仪像面具有黑暗的背景。其中Lyot光阑可遮拦日冕仪入射口径边缘衍射光所形成的衍射环。其结构参数根据衍射光波长的不同而有区别。为完全遮拦衍射环并保证到达像面的日冕辐射能量，需确定Lyot光阑合理参数，结合内掩式透射日冕仪，建模分析衍射环的成因,确定Lyot光阑的设计方法及对应参数，通过实验确认衍射环的实际尺寸和Lyot光阑设计参数的正确匹配关系， 且其具有较好的杂光遮拦效果，进而提高了日冕仪设计中杂散光的抑制能力。

Coronagraph is a device used to observe the corona by making a total solar eclipse-like image on the image plane. The dark background of the image plane is provided by the structures used to suppress the stray light in the coronagraph. The structure named Lyot stop is used to remove the diffracted ring formed by diffracted light from the edge of the front aperture. The structure parameters of the Lyot stop are adjusted based on the diffracted light of different wavelengths. The parameters of the Lyot stop are confirmed for removing the diffracted light entirety and enhancing the energy on the image plane radiated by solar corona. The cause of the diffraction rings is analyzed by the simulation of the internally occulting refractive coronagraph. The design and the parameters of the Lyot stop are determined by theoretical analysis. The feature size of the diffracted ring is matched with the parameters of the Lyot stop by the processing of the imaging. The effect of the stray-light suppression based on Lyot stop is achieved by the experiments. The capability of the stray-light suppression of coronagraph is improved.