Optimal shaped pupil coronagraphs for extrasolar planet finding

We examine several different approaches to achieving high contrast imaging of extrasolar planets. Rather than controlling the diffracted light by masking the star's image as in a classical coronagraph, we use the pupil's transmission function to focus the starlight. There are two broad classes of pupil coronagraphs examined in this paper: apodized pupils with spatially varying transmission functions and shaped pupils, whose transmission values are either 0 or 1. The latter are much easier to manufacture to the needed tolerances. This paper introduces several new shaped pupils and applies integration time and other metrics to them as well as to apodized pupils. These new designs can achieve nearly as high a throughput as the best apodized pupils and perform significantly better than the apodized square aperture design. The new shaped pupils enable searches of 50% - 100% of the detectable region, suppress the star's light to below 10^-10 of its peak value and have inner working distances as small as 2.8 λ/D.