# Phase-Apodized-Pupil Lyot Coronagraphs for Arbitrary Telescope Pupils

**Authors:** Emiel H. Por  
**arXiv:** [1908.02585](https://arxiv.org/abs/1908.02585)  
**Date:** 2019-08-07  
**Summary page:** https://www.summarizepaper.com/en/arxiv-id/1908.02585v1/

## Key points

- The Phase-Apodized-Pupil Lyot Coronagraph (PAPLC) combines two coronagraphs to improve imaging of exoplanets.
- A numerical optimization method is presented to obtain globally-optimal solutions for the phase apodizers for arbitrary telescope pupils.
- PAPLCs with annular focal-plane masks and point-symmetric dark zones perform similarly to their corresponding APLCs.
- With a knife-edge focal-plane mask and one-sided dark zones, PAPLC yields inner working angles as close as $1.4\lambda/D$ at contrasts of $10^{-10}$ and maximum post-coronagraphic throughput of more than 75% for telescope apertures with central obscurations up to 30%.
- Designs optimized for the VLT/SPHERE instrument and LUVOIR-A aperture demonstrate that even realistic telescope pupils can retain performance when using knife edge PAPLCs.
- This research provides an important step towards improving our ability to detect exoplanets by enhancing imaging capabilities through advanced coronagraph technology.

## Summary

The Phase-Apodized-Pupil Lyot Coronagraph (PAPLC) combines the apodized-pupil Lyot coronagraph (APLC) and the apodizing phase plate (APP) coronagraph to improve imaging of exoplanets. In this study, a numerical optimization method is presented to obtain globally-optimal solutions for the phase apodizers for arbitrary telescope pupils. The method is based on the linear map between complex-amplitude transmission of the apodizer and the electric field in the post-coronagraphic focal plane. PAPLCs with annular focal-plane masks and point-symmetric dark zones perform similarly to their corresponding APLCs. However, with a knife-edge focal-plane mask and one-sided dark zones, PAPLC yields inner working angles as close as $1.4\lambda/D$ at contrasts of $10^{-10}$ and maximum post-coronagraphic throughput of more than 75% for telescope apertures with central obscurations up to 30%. The authors present designs optimized for the VLT/SPHERE instrument and LUVOIR-A aperture that demonstrate that even realistic telescope pupils with struts, segments, and noncircular outer edges can retain performance when using knife edge PAPLCs. This research provides an important step towards improving our ability to detect exoplanets by enhancing imaging capabilities through advanced coronagraph technology.