  One of the main challenges for the direct imaging of planets around nearby
stars is the suppression of the diffracted halo from the primary star.
Coronagraphs are angular filters that suppress this diffracted halo. The
Apodizing Phase Plate coronagraph modifies the pupil-plane phase with an
anti-symmetric pattern to suppress diffraction over a 180 degree region from 2
to 7 {\lambda}/D and achieves a mean raw contrast of 10^-4 in this area,
independent of the tip-tilt stability of the system. Current APP coronagraphs
implemented using classical phase techniques are limited in bandwidth and
suppression region geometry (i.e. only on 1 side of the star). In this paper,
we show the vector-APP (vAPP) whose phase pattern is implemented by the
orientation of patterned liquid crystals. Beam-splitting according to circular
polarization states produces two, complementary PSFs with dark holes on either
side. We have developed a prototype vAPP that consists of a stack of 3 twisting
liquid crystal layers with a bandwidth of 500-900 nm. We characterize the
properties of this device using reconstructions of the pupil-plane pattern, and
of the ensuing PSF structures. By imaging the pupil between crossed and
parallel polarizers we reconstruct the fast axis pattern, transmission, and
retardance of the vAPP, and use this as input for a PSF model. This model
includes aberrations of the laboratory set-up, and matches the measured PSF,
which shows a raw contrast of 10^-3.8 between 2 and 7 {\lambda}/D in a 135
degree wedge. The vAPP coronagraph is relatively easy to manufacture and can be
implemented together with a broadband quarter-wave plate and Wollaston prism in
a pupil wheel in high-contrast imaging instruments. The manufacturing
techniques permit the application of phase patterns with deeper contrasts
inside the dark holes and enables unprecedented spectral bandwidths for
phase-manipulation coronagraphy.

Instrumentation and Methods for Astrophysics