  Sparse Aperture Masking (SAM) allows for high-contrast imaging at small inner
working angles, however the performance is limited by the small throughput and
the number of baselines. We present the concept and first lab results of
Holographic Aperture Masking (HAM) with extreme liquid-crystal geometric phase
patterns. We multiplex subapertures using holographic techniques to combine the
same subaperture in multiple non-redundant PSFs in combination with a
non-interferometric reference spot. This way arbitrary subaperture combinations
and PSF configurations can be realized, giving HAM more uv-coverage, better
throughput and improved calibration as compared to SAM, at the cost of detector
space.
