  The vector vortex coronagraph (VVC) performance in the laboratory and in
ground-based observatories has earned it a spot on the NASA mission concepts
HabEx and LUVOIR. The VVC induces a phase ramp through the manipulation of the
polarization state. Left- and right-circular polarizations get imprinted a
phase ramp of opposite signs, which prevents model-based focal plane wavefront
sensing and control strategies in natural light. We thus have to work with a
polarization state than ensures circularly polarized light at the VVC mask.
However, achieving this polarization state can be non trivial if there are
optics that add phase retardance of any kind between the circular polarizer and
the focal plane mask. Here we present the method currently used at the Caltech
high contrast spectroscopy testbed (HCST) to achieve the proper circular
polarization state for a VVC, which only uses the deformable mirror and
appropriate rotation of the circular polarizer and analyzer optics. At HCST we
achieve raw contrast levels of \tentoe~for broadband light with a VVC.
