A prism is a very simple and elegant way to create a hologram. It takes in white light, and sends out light of different colors into different direction. This is exactly the property that one would need to create a holographic screen, i.e. a screen which shows different pictures when viewed from different directions.
A pixel in a normal screen sends out a certain color of light into every direction. A pixel in a holographic screen needs to be able to send out specific colors of light into specific directions. There are some ways to do this, but none that I know are elegant and compact.

What we need is a sort of hyperprism: A component that takes in white light and depending on how we apply current to it sends different colors of this light into different directions.
Therefore I'm asking if anyone knows of physical components which have refractive properties that we can easily change by applying current, similarly to piezocrystals.