New Pupil Masks for High-Contrast Imaging

Motivated by the desire to image exosolar planets, recent work by us and others has shown that high-contrast imaging can be achieved using specially shaped pupil masks. To date, our masks have been symmetric with respect to a cartesian coordinate system but were not rotationally invariant, thus requiring that one take multiple images at different angles of rotation about the central point in order to obtain high-contrast in all directions. In this talk, we present two new classes of masks that have rotational symmetry and provide high-contrast in all directions with just one image. These masks provide the required 10 ^-10 level of contrast to within 4λ/D of the central point. They are also well-suited for use on ground-based telescopes, and perhaps NGST as well, since they can accommodate central obstructions and associated support spiders.