Fully broadband vAPP coronagraphs enabling polarimetric high contrast imaging
Abstract
We present designs for fully achromatic vector Apodizing Phase Plate (vAPP) coronagraphs, that implement low polarization leakage solutions and achromatic beam-splitting, enabling observations in broadband filters. The vAPP is a pupil plane optic, inducing the phase through the inherently achromatic geometric phase. We discuss various implementations of the broadband vAPP and set requirements on all the components of the broadband vAPP coronagraph to ensure that the leakage terms do not limit a raw contrast of 10-5. Furthermore, we discuss superachromatic QWPs based of liquid crystals or quartz/MgF2 combinations, and several polarizer choices. As the implementation of the (broadband) vAPP coronagraph is fully based on polarization techniques, it can easily be extended to furnish polarimetry by adding another QWP before the coronagraph optic, which further enhances the contrast between the star and a polarized companion in reflected light. We outline several polarimetric vAPP system designs that could be easily implemented in existing instruments, e.g. SPHERE and SCExAO.
- Publication:
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Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation III
- Pub Date:
- July 2018
- DOI:
- 10.1117/12.2312798
- arXiv:
- arXiv:1811.09775
- Bibcode:
- 2018SPIE10706E..5MB
- Keywords:
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- Astrophysics - Instrumentation and Methods for Astrophysics
- E-Print:
- 11 pages, 5 figures, presented at SPIE Astronomical Telescopes and Instrumentation 2018