  The challenge for optical detection of terrestial planet is the 25 magnitude
brightness contrast between the planet and its host star. This paper introduces
a new pupil design that produces a very dark null along its symmetry axis. By
changing the shape of the pupil, we can control the depth and location of this
null. This null can be further enhanced by combining this pupil with a rooftop
nuller or cateye nuller and an aperture stop. The performance of the optical
system will be limited by imperfections in the mirror surface. If the star is
imaged with and without the nuller, then we can characterize these
imperfections and then correct them with a deformable mirror. The full optical
system when deployed on a 6 $\times$ 10 m space telescope is capable of
detecting Earthlike planets around stars within 20 parsecs. For an Earthlike
planet around a nearby stars (10 parsecs), the telescope can characterize its
atmosphere by measuring spectral lines in the 0.3 - 1.3 micron range.
