An apparatus (3, 4L, 4R) for use in a near eye display device comprising: a first pair of in-coupling diffraction gratings (30a, 40a) having a first repeated diffraction spacing, d 1; a second pair of in-coupling diffraction gratings (30b, 40b) having a second repeated diffraction spacing, d 2; a first out-coupling diffraction grating and a second out-coupling diffraction grating, wherein each of the first and second out-coupling diffraction gratings (10, 20) comprises: a first region (12a, 22a) having the first repeated diffraction spacing, d 1, configured to out-couple light of a first wavelength to a user's eye, and a second region (12b, 22b) adjacent to the first region and having the second repeated diffraction spacing, d 2, different from the first spacing, d 1, configured to out-couple light of a second wavelength to the user's eye; wherein the first region of the first out-coupling diffraction grating is superposed on and aligned with the second region of the second out-coupling diffraction grating; wherein the second region of the first out-coupling diffraction grating is superposed on and aligned with the first region of the second out-coupling diffraction grating; wherein the first pair of in-coupling diffraction gratings (30a, 40a) are configured to direct light to the first region (12a, 22a) of respective ones of the first and second out-coupling diffraction gratings (10, 20); and wherein the second pair of in-coupling diffraction gratings (30b, 40b) are configured to direct light to the second region (12b, 22b) of respective ones of the first and second out-coupling diffraction gratings (10, 20). a first pair of in-coupling diffraction gratings (30a, 40a) having a first repeated diffraction spacing, d 1; a second pair of in-coupling diffraction gratings (30b, 40b) having a second repeated diffraction spacing, d 2; a first out-coupling diffraction grating and a second out-coupling diffraction grating, wherein each of the first and second out-coupling diffraction gratings (10, 20) comprises: a first region (12a, 22a) having the first repeated diffraction spacing, d 1, configured to out-couple light of a first wavelength to a user's eye, and a second region (12b, 22b) adjacent to the first region and having the second repeated diffraction spacing, d 2, different from the first spacing, d 1, configured to out-couple light of a second wavelength to the user's eye; a first region (12a, 22a) having the first repeated diffraction spacing, d 1, configured to out-couple light of a first wavelength to a user's eye, and a second region (12b, 22b) adjacent to the first region and having the second repeated diffraction spacing, d 2, different from the first spacing, d 1, configured to out-couple light of a second wavelength to the user's eye; wherein the first region of the first out-coupling diffraction grating is superposed on and aligned with the second region of the second out-coupling diffraction grating; wherein the second region of the first out-coupling diffraction grating is superposed on and aligned with the first region of the second out-coupling diffraction grating; wherein the first pair of in-coupling diffraction gratings (30a, 40a) are configured to direct light to the first region (12a, 22a) of respective ones of the first and second out-coupling diffraction gratings (10, 20); and wherein the second pair of in-coupling diffraction gratings (30b, 40b) are configured to direct light to the second region (12b, 22b) of respective ones of the first and second out-coupling diffraction gratings (10, 20).