A display system comprising: an optical waveguide having an incoupling grating, an intermediate grating formed by modulations on a first surface of the optical waveguide, and an exit grating; and a light engine (13, 15) configured to generate multiple input beams, each beam corresponding to a respective active image point and being substantially collimated and directed to the incoupling grating in a unique inward direction, whereby the multiple input beams form a virtual image; wherein the intermediate and exit grating have widths substantially larger than the beams' diameters; wherein the incoupling grating is arranged to couple each beam into the intermediate grating, in which that beam is guided onto multiple splitting regions of the intermediate grating in a direction along the width of the intermediate grating; wherein the intermediate grating is arranged to split that beam at the splitting regions to provide multiple substantially parallel versions of that beam which are coupled into the exit grating, in which the multiple versions are guided onto multiple exit regions of the exit grating, the exit regions lying in a direction along the width of the exit grating; wherein the exit grating is arranged to diffract the multiple versions of that beam outwardly, the multiple input beams thus causing multiple exit beams to exit the waveguide which form a version of the virtual image; and characterized in that: a polarization state of each beam interacting with the modulations forming the intermediate grating on the first surface of the optical waveguide is controlled by a retarder film on a second surface of the optical waveguide opposing the first surface, and a retardation pattern of the retarder film is dynamically variable. an optical waveguide having an incoupling grating, an intermediate grating formed by modulations on a first surface of the optical waveguide, and an exit grating; and a light engine (13, 15) configured to generate multiple input beams, each beam corresponding to a respective active image point and being substantially collimated and directed to the incoupling grating in a unique inward direction, whereby the multiple input beams form a virtual image; wherein the intermediate and exit grating have widths substantially larger than the beams' diameters; wherein the incoupling grating is arranged to couple each beam into the intermediate grating, in which that beam is guided onto multiple splitting regions of the intermediate grating in a direction along the width of the intermediate grating; wherein the intermediate grating is arranged to split that beam at the splitting regions to provide multiple substantially parallel versions of that beam which are coupled into the exit grating, in which the multiple versions are guided onto multiple exit regions of the exit grating, the exit regions lying in a direction along the width of the exit grating; wherein the exit grating is arranged to diffract the multiple versions of that beam outwardly, the multiple input beams thus causing multiple exit beams to exit the waveguide which form a version of the virtual image; and characterized in that: a polarization state of each beam interacting with the modulations forming the intermediate grating on the first surface of the optical waveguide is controlled by a retarder film on a second surface of the optical waveguide opposing the first surface, and a retardation pattern of the retarder film is dynamically variable.