Over the last decade, the vector-apodizing phase plate (vAPP) coronagraph has been developed from concept to on-sky application in many high-contrast imaging systems on 8mclass telescopes. The vAPP is a geometric-phase patterned coronagraph that is inherently broadband, and its manufacturing is enabled only by direct-write technology for liquid-crystal patterns. The vAPP generates two coronagraphic point spread functions (PSFs) that cancel starlight on opposite sides of the PSF and have opposite circular polarization states. The efficiency, that is, the amount of light in these PSFs, depends on the retardance offset from a half-wave of the liquid-crystal retarder. Using different liquid-crystal recipes to tune the retardance, different vAPPs operate with high efficiencies (>96%) in the visible and thermal infrared (0.55 μmto 5 μm). Since 2015, seven vAPPs have been installed in a total of six different instruments, includingMagellan/MagAO,Magellan/MagAO-X, Subaru/SCExAO, and LBT/LMIRcam. Using two integral field spectrographs installed on the latter two instruments, these vAPPs can provide lowresolution spectra (R∼30) between 1 μmand 5 μm.We review the design process, development, commissioning, on-sky performance, and first scientific results of all commissioned vAPPs. We report on the lessons learned and conclude with perspectives for future developments and applications.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Engineering (miscellaneous)
- Electrical and Electronic Engineering