Finding Terrestrial Planets Using Eighth-Order Image Masks

We offer a new series of image masks for coronagraphy that are insensitive to pointing errors and other low-spatial-frequency optical aberrations. For a modest cost in throughput, these “eighth-order” band-limited masks would allow the Terrestrial Planet Finder (TPF) to operate with a pointing accuracy no better than that of the Hubble Space Telescope. We also provide eighth-order notch filter masks that offer the same robustness to pointing errors and should be relatively easy to construct: binary masks and graded masks with moderate optical density requirements. Subject headings: astrobiology — circumstellar matter — instrumentation: adaptive optics — planetary systems