US Patent 10962787 Waveguide display device

An optical waveguide includes an input diffractive optical element arranged for being aligned with an optical projector for diffracting light beams therefrom, a waveguide substrate n, and an output diffractive optical element. Light beams diffracted by the output diffractive optical element are coupled out of the waveguide substrate towards users' eyes. The output diffractive optical element has an effective area arranged to maintain a constant output flux per unit area therein for providing an uniform image in brightness when the image is being projected out of the waveguide substrate.