The Pupil‐swapping Coronagraph

A new coronagraph that performs destructive interference between copies of the telescope pupil in which "slices" have been swapped is studied in this paper. A fourth‐order "pupil‐swapping coronagraph" is particularly attractive for direct imaging of extrasolar terrestrial planets: it achieves 100% throughput at 1.4 λ/d on a square pupil (72.5% at 1.77 λ/d on a circular pupil), is compatible with a central obstruction and spiders, and delivers sharp images of off‐axis sources. Direct detection of extrasolar terrestrial planets appears theoretically feasible on a 2 to 3 m visible‐wavelength telescope in space.