Have you ever thought about making fresnel lenses out of rippling fluid? Like, sound in water or whatever. Making fine ripple pattern for lens or diff grate.
I don't know if anyone has used ripples in a liquid, but LCD's without polarizers are used in tomography to dynamically configure a diffraction or phase-shift pattern. https://en.m.wikipedia.org/wiki/Spatial_light_modulator
It would be kinda programmable too.