Folded optical path heads-up display system

A heads-up display (HUD) system comprising:

• a display employed to emit light rays;
• a first reflective interface arranged obliquely along an optical path of the light rays emitted from the display;
• a second transparent interface obliquely oriented with respect to the optical path of the light rays reflected from the first reflective interface, wherein the light rays, after reflection from the first reflective interface, are incident on the second transparent interface from within a first optical medium, the second transparent interface being a boundary between the first optical medium having a first refractive index (n1) and a second optical medium having a second refractive index (n2) that is smaller than the first refractive index, and wherein the light rays are incident on the boundary at angles greater than a critical angle for the first optical medium and the second optical medium, whereby the light rays undergo total internal reflection;
• and
• a third semi-reflective interface arranged obliquely along the optical path of the light rays reflected from the second transparent interface, the third semi-reflective interface being oriented to reflect the light rays toward an eyebox of the HUD system, while optically combining the light rays with a real-world light field,
• wherein the first reflective interface, the second transparent interface and the third semi-reflective interface are integrated into a single optical structure.