US Patent 10120194 Wide field personal display

A display apparatus has an image generator that generates image-bearing light from a f surface and a lens spaced apart from the image generator and having an aspheric incident refractive surface concave to the image generator and having an aspheric reflective surface concave to the image generator, wherein a principal axis of the reflective surface is normal to the image generator. A beam splitter plate disposed in free space between the image generator and the lens has first and second parallel surfaces that are oblique to a line of sight of a viewer. The lens and the beam splitter plate define a viewer eye box for the image-bearing light along the line of sight of the viewer.