A display system having a viewing window, wherein the display system comprises: a pair of surfaces (1002, 1005) arranged to form a waveguide, wherein a first surface of the pair of surfaces (1002, 1005) is transmissive-reflective and the second surface is reflective; a circular polarizer arranged in cooperation with the first surface wherein the circular polarizer is arranged to apply a circular polarization to incident ambient light, before it enters the waveguide via the first surface; wherein the waveguide is arranged to guide the circularly polarized ambient light by internal reflection between the pair of surfaces (1002, 1005) and to partially transmit the circularly polarized ambient light via the first surface, towards the circular polarizer; wherein the circular polarizer is arranged to block onward transmission of said circularly polarized ambient light, when it is transmitted to the circular polarizer from the first surface of the waveguide; the display system characterised by: further comprising a picture generating unit arranged to display a hologram of a picture and inject spatially-modulated light formed from the hologram into the waveguide such that the spatially-modulated light is partially guided along the waveguide by internal reflection between the pair of surfaces (1002, 1005) and partially transmitted by the first surface at a plurality of locations thereon in order to form a substantially continuous viewing window, via which a viewer may receive the spatially-modulated light; wherein the spatially-modulated light injected into the waveguide is circularly polarized and the display system is configured such that the circularly polarized spatially modulated light is transmitted by the circular polarizer after partial transmission through the first surface at each location of the plurality of locations. a pair of surfaces (1002, 1005) arranged to form a waveguide, wherein a first surface of the pair of surfaces (1002, 1005) is transmissive-reflective and the second surface is reflective; a circular polarizer arranged in cooperation with the first surface wherein the circular polarizer is arranged to apply a circular polarization to incident ambient light, before it enters the waveguide via the first surface; wherein the waveguide is arranged to guide the circularly polarized ambient light by internal reflection between the pair of surfaces (1002, 1005) and to partially transmit the circularly polarized ambient light via the first surface, towards the circular polarizer; wherein the circular polarizer is arranged to block onward transmission of said circularly polarized ambient light, when it is transmitted to the circular polarizer from the first surface of the waveguide; the display system characterised by: further comprising a picture generating unit arranged to display a hologram of a picture and inject spatially-modulated light formed from the hologram into the waveguide such that the spatially-modulated light is partially guided along the waveguide by internal reflection between the pair of surfaces (1002, 1005) and partially transmitted by the first surface at a plurality of locations thereon in order to form a substantially continuous viewing window, via which a viewer may receive the spatially-modulated light; wherein the spatially-modulated light injected into the waveguide is circularly polarized and the display system is configured such that the circularly polarized spatially modulated light is transmitted by the circular polarizer after partial transmission through the first surface at each location of the plurality of locations. further comprising a picture generating unit arranged to display a hologram of a picture and inject spatially-modulated light formed from the hologram into the waveguide such that the spatially-modulated light is partially guided along the waveguide by internal reflection between the pair of surfaces (1002, 1005) and partially transmitted by the first surface at a plurality of locations thereon in order to form a substantially continuous viewing window, via which a viewer may receive the spatially-modulated light; wherein the spatially-modulated light injected into the waveguide is circularly polarized and the display system is configured such that the circularly polarized spatially modulated light is transmitted by the circular polarizer after partial transmission through the first surface at each location of the plurality of locations.