  Liquid crystals allow for the real-time control of the polarization of light.
We describe and provide some experimental examples of the types of general
polarization transformations, including universal polarization transformations,
that can be accomplished with liquid crystals in tandem with fixed waveplates.
Implementing these transformations with an array of liquid crystals, e.g., a
spatial light modulator, allows for the manipulation of the polarization across
a beam's transverse plane. We outline applications of such general spatial
polarization transformations in the generation of exotic types of vector
polarized beams, a polarization magnifier, and the correction of polarization
aberrations in light fields.
