OPTICAL ENGINE FOR HEAD-MOUNTED DISPLAY APPARATUS

A display apparatus has a display to emit image-bearing light to a prism assembly that defines an optical path between an incident surface of the prism assembly and an output surface that is orthogonal to within +/−30 degrees relative to the incident surface, wherein the prism assembly has a curved reflective surface opposite the incident surface. The prism assembly encases a beam splitter at an oblique angle to the defined optical path and to both the incident and the output surface of the prism assembly. A shim, in contact against the display surface and against the incident surface of the prism assembly, defines a sealed air gap for light between the display surface and the incident surface. A frame houses the display, the shim, and the incident surface of the prism assembly, wherein the frame further provides connection features for coupling the apparatus to a head-worn article.