PIAA Coronagraph designs for segmented apertures, robust to low-order aberrations
Abstract
To directly image and characterize exoplanets, internal starlight suppression systems rely on coronagraphs to optically remove starlight while preserving planet light for spectroscopy. The Phase-Induced Amplitude Apodization family of coronagraphs (PIAA) represent an attractive option for the next generation of large space telescopes optimized for habitable exoplanet imaging, offering high throughput and small inner working angle (IWA). A version of PIAA called PIAACMC (complex-valued mask coronagraph) is also compatible with segmented apertures, preserving much of the throughput and resolution of a monolithic pupil, at least for small stellar sizes. Coronagraph compatibility with segmented apertures is essential for the success of habitable planet characterization with future large apertures, such as the Large UV / Optical/ Infrared (LUVOIR) concept currently under consideration by the 2020 astrophysics decadal survey. The high performance of PIAA can 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 large stellar angular sizes. In this paper, we show a family of classic PIAA designs for LUVOIR B that feature high tolerance to stellar angular sizes. In particular, we show a design where 1e-10 contrast can be maintained for stellar diameters of 0.1 l/D, and IWA of 3 l/D. We also show that current coronagraph performance is limited by engineering and not physics, and that with further development, it is possible for coronagraphs to have much better inner working angles while being tolerant to 0.1 l/D diameter stars, resulting in science yield increases of a factor of 2 or 3 for missions like LUVOIR and HabEx. Thus, although there are relatively mature coronagraphs today which already result in compelling missions, the technology in general is still far from fundamental physics limits.
- Publication:
-
American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23513007B