The invention relates to a space-
ray-tracing-based method for designing a
secondary mirror hood and a square-tapered
extinction cone. The method comprises: step one, establishing a Cartesian rectangular coordinate
system used during a
design process; step two, establishing auxiliary light in a
meridian plane and a sagittal surface and carrying out calculation to obtain a boundary of a square-tapered main mirror central-hole
extinction cone; step three, determining the position and configuration of the
tail end of the square-tapered main mirror central-hole
extinction cone; step four, definingan initial structure of a
secondary mirror hood; step five, constructing a spatial auxiliary
ray and carrying out calculation to obtain the position and configuration of the front end of a square-tapered extinction cone; step six, setting a
point light source set at the edge of a
conical surface, carrying out
ray tracing, carrying out statistics of
light source numbers with light leakage possibility, and increasing the size of the
conical surface correspondingly; step seven, determining final spatial positions and three-dimensional configuration of the
tail end and the front end of the square-tapered main mirror central-hole extinction cone; and step eight, carrying out calculation to obtain three-dimensional configuration of the
secondary mirror hood.