US Patent 8665178 Partially-reflective waveguide stack and heads-up display using same

An apparatus that includes a waveguide comprising a front surface, a back surface and an embedded structure between the front surface and the back surface. A reflective array is formed by at least part of the embedded structure. The reflective array includes a plurality of wedges, each wedge having a primary facet, a secondary facet, and a plateau facet wherein at least one of the plurality of primary facets is at least partially reflective. Other implementations are disclosed and claimed.