Design and performance analysis of a PIAACMC coronagraph on a segmented aperture

Abstract

To directly image and characterize exoplanets, starlight suppression systems rely on coronagraphs to optically remove starlight while preserving planet light for spectroscopy. The Phase-Induced Amplitude Apodization Complex Mask Coronagraph (PIAACMC) is an attractive coronagraph option for the next generation of large space telescopes optimized for habitable exoplanet imaging: PIAACMC offers high throughput, small inner working angle (IWA) with little loss in image quality. PIAACMC is also compatible with segmented apertures, preserving much of the throughput and resolution of a full pupil. 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 way to inform the 2020 decadal survey. We present a design of PIAACMC for a segmented aperture, using the segmented aperture currently considered for LUVOIR as a representative case. This design is optimized to be resilient to tip/tilt jitter and large stellar angular sizes. This also enables it to have improved tolerance to polarization-specific aberrations, which are dominated by low-order modes such as tip-tilt and astigmatism. We simulate and study the performance of this design using a simplified instrument model. These simulations include wavefront control and tip-tilt errors. We characterize the performance of our design in monochromatic as well as broadband light in terms of throughput, inner working angle, contrast, area of the dark zone, and sensitivity to low-order aberrations.