The Phase-Induced Amplitude Apodization (PIAA) technique represents a family of high performance coronagraphs with high throughput, aggressive inner working angles (IWAs), and compatible with obstructed apertures. This is particularly important because Large UV / Optical/ Infrared (LUVOIR) and HabEx B concepts currently considered for the 2020 decadal survey are based on obstructed and/or segmented apertures. Higher throughputs and IWAs enable significant science gains, or significant savings in size and cost of a mission without reducing science. Historically, however, PIAA-based designs on segmented apertures (PIAACMC) were also sensitive to low order aberrations such as tip/tilt jitter, as well as large stellar angular sizes.
In this paper, we show a classic PIAA design for the segmented aperture of LUVOIR B that features high tolerance to low-order aberrations. It can gain arbitrarily good sensitivity to low order aberrations at the expense of IWA, by varying the size of the focal plane mask. Missions can either commit to a single mask, or have several masks, selecting the one best suited for each target’s stellar size, which can further increase science yield. We find that in order to maintain 1e-10 contrast for stellar diameters of 0.1 l/D, the IWA needs to be enlarged to 3 l/D. Finally, we show that in theory, it is possible for coronagraphs to have much better inner working angles while being tolerant to 0.1 l/D diameter stars, so there is still a lot of opportunity to improve the science yield of a given mission by developing even better coronagraphs.
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