Vol 15, No 3

A high-contrast coronagraph for direct imaging of Earth-like exoplanets: design and test

Cheng-Chao Liu, De-Qing Ren, Jiang-Pei Dou, Yong-Tian Zhu, Xi Zhang, Gang Zhao, Zhen Wu, Rui Chen


Abstract A high-contrast coronagraph for direct imaging of an Earth-like exoplanet at the visible band needs a contrast of 10−10 at a small angular separation of 4λ/D or less. Here we report our recent laboratory experiment that approaches these limits. Our test of a high-contrast imaging coronagraph is based on our step-transmission apodized filter. To achieve this goal, we use a liquid crystal array as a phase corrector to create a dark hole based on our dedicated algorithm. We have suppressed the diffraction and speckle noise near the point image of a star to a level of 1.68 × 10−9 at 4λ/D, which can be used for direct imaging of Jupiter-like exoplanets. This demonstrates that a telescope incorporating a high-contrast coronagraph in space has the potential to detect and characterize Earth-like planets.


Keywords instrumentation: coronagraph, liquid crystal array — techniques: apodization — methods: laboratory

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