# Broadband Vector Vortex Coronagraph Testing at NASA's High Contrast Imaging Testbed Facility

**Authors:** Garreth Ruane, A J Eldorado Riggs, Eugene Serabyn, Wesley Baxter, Camilo Mejia Prada, Dimitri Mawet, Matthew Noyes, Phillip K. Poon, Nelson Tabiryan  
**arXiv:** [2207.13742](https://arxiv.org/abs/2207.13742)  
**Date:** 2022-07-27  
**Summary page:** https://www.summarizepaper.com/en/paper/2207.13742v1/

## Key points

- The study discusses the potential of vector vortex coronagraphs for directly imaging exoplanets with off-axis space telescopes.
- Achieving the required image contrast to observe light reflected from Earth-sized planets in a laboratory setting has been challenging.
- Recent advances in liquid crystal vector vortex waveplate manufacturing and system-level performance improvements have enabled researchers to achieve raw contrast levels of 1.57$\times10^{-9}$ and 5.86$\times10^{-9}$ in 10% and 20% optical bandwidths, respectively, representing a factor of ten improvement over previously reported performance levels.
- The authors provide experimental comparisons of achieved contrast as a function of spectral bandwidth and estimate limiting error terms while discussing necessary improvements to close the gap in contrast performance required for future exoplanet imaging space telescopes.
- The study highlights the potential of vector vortex coronagraphs as promising technologies for directly imaging exoplanets with off-axis space telescopes, provided that further advancements can be made to improve image contrast levels.

## Summary

In a recent study titled "Broadband Vector Vortex Coronagraph Testing at NASA's High Contrast Imaging Testbed Facility," Garreth Ruane and colleagues discuss the potential of vector vortex coronagraphs for directly imaging exoplanets with off-axis space telescopes. While the theoretical performance of an ideal vector vortex coronagraph is unparalleled, achieving the required image contrast to observe light reflected from Earth-sized planets ($\sim10^{-10}$) in a laboratory setting has been challenging. However, recent advances in liquid crystal vector vortex waveplate manufacturing and system-level performance improvements have enabled the researchers to achieve raw contrast levels of 1.57$\times10^{-9}$ and 5.86$\times10^{-9}$ in 10% and 20% optical bandwidths, respectively, averaged over 3-10$\lambda/D$ separations on one side of the pseudo-star. These results represent a factor of ten improvement over previously reported performance levels. The authors provide experimental comparisons of achieved contrast as a function of spectral bandwidth and estimate limiting error terms while discussing necessary improvements to close the gap in contrast performance required for future exoplanet imaging space telescopes. The study highlights the potential of vector vortex coronagraphs as promising technologies for directly imaging exoplanets with off-axis space telescopes, provided that further advancements can be made to improve image contrast levels. With these advancements, it may be possible to bridge the gap between theoretical performance and laboratory results, allowing for more accurate observation of exoplanets through off-axis space telescopes.