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 coronagraphic instrument that makes artificial total solar eclipse images on an image surface. The stray coronagraphic structure allows the coronagraphic image to have a dark background. The Lyot diaphragm can block the diffraction ring formed by diffracted light from the edge of the coronal instrument’s entrance aperture. The structural parameters are differentiated according to the wavelength of diffracted light. In order to completely obscure the diffraction ring and ensure the coronal radiant energy reaching the image plane, the reasonable parameters of the Lyot aperture should be determined. Combined with the inner-mask transmission coronagraph, the origin of the diffraction ring was analyzed and the Lyot aperture design method and its corresponding parameters were determined. The correct match between the actual size of the diffract ring and the design parameters of the Lyot diaphragm is confirmed through experiments, and it has good effect of stray light obscuration, thereby improving the inhibitory ability of the stray light in the design of the coronagraph.