A near eye display assembly comprising: (a) an image source; and (b) a combiner as a first reflective surface and a secondary mirror optically coupled to the combiner as a second reflective surface, or a waveguide optically coupled to the image source; wherein the combiner or the waveguide are adapted to convey image information from outside a field of view of a viewer into the field of view of the viewer; wherein the combiner and the secondary mirror are in an off-axis folded geometry; wherein at least one of the combiner, the secondary mirror, and the waveguide includes a freeform nanostructured surface having a meta-grating at least partially defined by a unit cell having a plurality of meta-atoms, whereby each of the meta-atoms in the unit cell has a different length to width ratio; wherein the freeform property of the nanostructured surface is either configured to correct optical aberrations induced by tilting and decentering of the first reflective surface and the second reflective surface, or aspects of the nanostructured surface are used to couple light into or out of the waveguide; and wherein the meta-grating is further configured to provide at least 50% +1 diffraction order Transverse Electric polarized absolute grating efficiency at a desired wavelength of the visible light spectrum in reflection, within a range of operation of an angle of incidence that spans about 20°. (a) an image source; and (b) a combiner as a first reflective surface and a secondary mirror optically coupled to the combiner as a second reflective surface, or a waveguide optically coupled to the image source; wherein the combiner or the waveguide are adapted to convey image information from outside a field of view of a viewer into the field of view of the viewer; wherein the combiner and the secondary mirror are in an off-axis folded geometry; wherein at least one of the combiner, the secondary mirror, and the waveguide includes a freeform nanostructured surface having a meta-grating at least partially defined by a unit cell having a plurality of meta-atoms, whereby each of the meta-atoms in the unit cell has a different length to width ratio; wherein the freeform property of the nanostructured surface is either configured to correct optical aberrations induced by tilting and decentering of the first reflective surface and the second reflective surface, or aspects of the nanostructured surface are used to couple light into or out of the waveguide; and wherein the meta-grating is further configured to provide at least 50% +1 diffraction order Transverse Electric polarized absolute grating efficiency at a desired wavelength of the visible light spectrum in reflection, within a range of operation of an angle of incidence that spans about 20°. wherein the combiner or the waveguide are adapted to convey image information from outside a field of view of a viewer into the field of view of the viewer; wherein the combiner and the secondary mirror are in an off-axis folded geometry; wherein at least one of the combiner, the secondary mirror, and the waveguide includes a freeform nanostructured surface having a meta-grating at least partially defined by a unit cell having a plurality of meta-atoms, whereby each of the meta-atoms in the unit cell has a different length to width ratio; wherein the freeform property of the nanostructured surface is either configured to correct optical aberrations induced by tilting and decentering of the first reflective surface and the second reflective surface, or aspects of the nanostructured surface are used to couple light into or out of the waveguide; and wherein the meta-grating is further configured to provide at least 50% +1 diffraction order Transverse Electric polarized absolute grating efficiency at a desired wavelength of the visible light spectrum in reflection, within a range of operation of an angle of incidence that spans about 20°.