Abstract
There has been proposed the Starshade that enables direct observation of exoplanet orbiting around the host star by arranging membrane called occulter of several tens of meters radius between the space telescope and the star so that it blocks the light from the stars to the telescope. This paper derives the electric field of the diffracted light when the occulter blocks the light of the star, and calculates the optimal shape of the occulter to minimize the contrast. In the calculation, two patterns of apodization functions are employed, and the results are compared with each other. The shape of the occulter is like a flower petal, and the optimal shape and the contrast at the pupil plane are obtained by assuming the number of the petals.
