Optimal design of petal-shaped occulters for extra-solar planet detection

One of the proposed methods for directly imaging extrasolar planets is via a free-flying occulter for blocking the starlight. The occulter would fly between a conventional telescope and the target star. It has long been known that a solid occulting disk does not produce a deep shadow; diffraction effects result in a bright spot in the center that would mask a planet. However, utilizing recent results in shaped pupil optimization, we have developed designs for an occulter with a shape that does effectively block the light from the star, allowing the planet light to be seen even at a small angular separation. The shadow created by the occulter is wavelength-dependent and quite sensitive to the shape of the outer edge. We present an optimization approach for producing these occulter designs to meet contrast requirements over multiple wavelengths and also discuss tolerancing requirements on the shade manufacture and control.