US Patent 9804396 Head-mounted display with an eyeball-tracker integrated system

Head-mounted display with an eye-tracking system and including a light-transmitting substrate (20) having two major surfaces and edges, optical means for coupling light into said substrate (20) by total internal reflection, partially-reflecting surfaces (22a-22c) carried by the substrate (20) that are not parallel with the major surfaces of the substrate (20), a near-infrared light source (78) and a display source (92) projecting within the photopic spectrum, wherein light from the light source (78) and light from the display source (92) are coupled into the substrate (20) by total internal reflection.