US Patent 10983338 Exit-pupil expander used distribute light over a liquid-crystal variable retarder

An optical device includes a liquid-crystal variable retarder. An exit-pupil expander is optically coupled to the liquid-crystal variable retarder, the exit-pupil expander includes: at least one optical input feature that receives reference light from a reference light source; and one or more optical coupling elements coupled to receive the reference light from the reference light source and expand the reference light to one or more spatially-separated regions of the liquid-crystal variable retarder.