In the ERC StG project FALCONER we have developed novel coronagraphic components and optical systems based on patterned liquid-crystal technology. The overall aim is to enable direct imaging of exoplanets, and moreover the characterization of the atmospheres of exoplanets through spectroscopy and polarimetry. We mainly focus on the so-called vector-APP coronagraph, which is a pupil-plane phase mask that delivers two complementary point-spread functions with dark holes in which exoplanets can be observed. During this project, we have designed, tested, and implemented new coronagraphic masks with unprecedented contrast performance over large spectral bandwidths. Specifically, we have developed vAPP coronagraphs for Subaru/SCExAO, LBT/LMIRcam, WHT/LExI, MagAO-X, VLT/ERIS and the balloon experiment HiCIBaS. Moreover, we have designed vAPP coronagraphs for the ELT instruments MICADO and METIS. With our novel multiple-grating technique we have invented a generic solution for the polarization-leakage problem of such devices, with promising applications also for focal-plane coronagraphs like the Vector Vortex Coronagraph, particularly for space-based implementation for future direct observations of potentially habitable exoplanets orbiting solar-type stars. With the complex phase patterns enabled by the liquid-crystal technology, we have fully incorporated wavefront sensing from the focal plane.
Moreover, we have applied the same liquid-crystal technology to develop the optimal vector-Zernike wavefront sensor, Holographic Aperture Masking spectroscopic interferometry (installed at Keck/OSIRIS), and novel polarimetric approaches for remote-sensing of life.
In addition, the FALCONER team has provided the first 3-4 um spectra of HR8799 c,d,e with the vAPP360 at LBT, has provided the first direct discovery of a polarization signal of a substellar companion (DH Tau b; due to the presence of a circumplanetary disk), and has contributed to the direct detections of exoplanets YSES1b&c and YSES2b. Finally, FALCONER researchers have developed new polarimetric techniques and instrumentations for the unambiguous discovery of life through the circular polarization signatures of homochiral biomolecules, and are building instruments for the ISS and a lunar lander to test these techniques on planet Earth.
