Design of two-dimensional waveguide head-up display

The strive for the small volume and light weight in head-up displays has made the conventional configuration combining relay optics and combiner unpractical any more. In this paper, a compact and light-weight head-up display with a large eyebox is designed, with two orthogonal geometrical waveguides adopted to extend the exit pupil in both directions. This two-dimensional waveguide acts as a pupil expander, which can also save the whole system from the trouble of severe aberrations. A triangular prism serves as the input-coupling and the partially reflective mirrors array is used as the output-coupling. Parameters to shape the combined waveguide are derived. The spherical surface based coaxial projection system to match the combined waveguide are designed to project and magnify the virtual image onto a surface at infinity. The compact head-up display integrating projection optics and the combined waveguide has a horizontal field of 20°, with an eyebox of 80 mmx80 mm.