Phase apodization coronagraphs are implemented in a pupil plane to create a
dark hole in the science camera focal plane. They are successfully created as
"Apodizing Phase Plates" (APPs) using classical optical manufacturing, and as
"vector-APPs" using liquid-crystal patterning with essentially achromatic
performance. This type of coronagraph currently delivers excellent broadband
contrast (∼10−5) at small angular separations (few λ/D) at
ground-based telescopes, owing to their insensitivity to tip/tilt errors.Comment: Invited chapter, to be published in the "Handbook of Astronomical
Instrumentation", Vol. 3, eds. A. Moore and D. Burrows, WSPC (2018). 9 pages,
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