A display comprises: a transmissive pixellated spatial light modulator (21); and a backlight (22). The backlight has a light-transmissive waveguide (26), with a first face of the waveguide being opposed to the spatial light modulator (21). The first face of the waveguide comprises a plurality of regions that are not totally internally reflective for at least one polarisation of light propagating within the waveguide, and the remainder of the first face of the waveguide is totally internally reflective for light propagating within the waveguide. Light is extracted from the waveguide at the regions where first face of the waveguide is not totally internally reflective. The pitch of the regions where first face of the waveguide is not totally internally reflective is substantially an integer multiple of the pitch of the pixels of the spatial light modulator.