  Current scalar coronagraph focal plane mask designs are performance-limited
by chromaticity. We investigate the effects of adding central Roddier and dual
zone phase dimples to scalar vortex masks to improve broadband performance by
suppressing the chromatic stellar leakage. We present hybrid designs with
radial phase dimples integrated with the sawtooth vortex, wrapped vortex, and
cosine phase mask. We show that using these dimples, it is possible to
substantially improve the broadband contrast performance of scalar phase masks.
We also show that although adding a phase dimple does not increase the
sensitivity to low-order aberrations, suppressing the central leakage of scalar
vortex coronagraphs does not restore the aberrations sensitivities to their
notional state.
