Compact Head-Up Display and Waveguide Therefor

A waveguide comprising:

• a pair of opposing surfaces arranged to guide a light field therebetween by internal reflection, the light field comprising light rays having a plurality of different light ray angles;
• an input port arranged to receive the light field from a display system, wherein the input port comprises a first transmissive-reflective element disposed on a first surface of the pair of opposing surfaces, the first transmissive-reflective element comprising a partially transmissive and partially reflective surface coating having a transmissivity of between 0.1 to 0.5, the first transmissive-reflective element configured to partially transmit and partially reflect at least a portion of the light field from the display system;
• a reflective element disposed on the first surface of the pair of opposing surfaces adjacent to the first transmissive-reflective element, wherein one of the first transmissive-reflective element or the reflective element is configured to internally reflect within the waveguide light rays of the light field that are incident thereon after being reflected from a second surface of the pair of opposing surfaces;
• and
• an output port formed by a second transmissive-reflective element disposed on the second surface of the pair of opposing surfaces, wherein the second transmissive-reflective element is such that the light field is divided at each internal reflection and a plurality of replicas of the light field are transmitted out of the waveguide through the output port.