Patent ID: 7751662

Claim:
An optical display device comprising: a) an essentially planar light guide; b) an image-generating system; c) a first diffraction grating by which light that comes from the image-generating system can be coupled into the light guide; and d) a second diffraction grating by which the light can be coupled out again from the light guide; wherein e) at least one of the two diffraction gratings is a binary-blazed grating having a multiplicity of diffraction structures, which essentially extend mutually parallel, have a width g perpendicular to their lengthwise direction which is greater than the effective wavelength of the light that comes from the image-generating system, and are composed of a multiplicity of individual substructures that ensure a blaze effect and have a maximum dimension p in the lengthwise direction of the diffraction structures which at least on average over a diffraction structure is less than the wavelength of the light, and wherein the diffraction structures respectively include a row of individual substructures along a lengthwise direction, which in plan view have the shape of a closed geometrical surface whose dimension directed parallel to the lengthwise direction of the diffraction structures varies in a direction perpendicular to the lengthwise direction of the diffraction structures, and which have a maximum dimension in the direction perpendicular to the lengthwise direction of the diffraction structures, which is greater than the wavelength of the light.