A polarization rotator is provided for rotating the polarization direction of linearly polarized light by any arbitrary angle other than 90. The device comprises a layer of liquid crystal material disposed between alignment surfaces. In one mode, a 90 twist is induced in the liquid crystal director. An expression is provided for relating the retardation of the layer to the amount of polarization rotation and the angle between the polarization direction of incident light and the alignment direction at the input side of the liquid crystal layer.