Computation of the diffracted field of a toothed occulter by the semi-infinite rectangle method.

To observe the solar corona, stray light in the coronagraph, arising primarily from an external occulter and diaphragm illuminated directly by the Sun, should be strongly suppressed. A toothed occulter and diaphragm can be used to suppress stray light because they diffract much less light in the central area than a circular disk. This study develops a method of computing the light diffracted by a toothed occulter and diaphragm, obtaining the optimum shape using this method. To prove the method's feasibility, the diffracted fields of circular and rectangular disks are computed and compared with those calculated by a conventional method.