in movie projection screens and non coherent light head up displays laser projection viewing etc as the present invention produces much sharper images than those afforded by traditional holographic optical diffusers application_number US 201414469277 A description the present invention a composite holographic optical diffuser and method of fabrication thereof comprises a composite surface relief structure which acts as a suppressor to visible optical artifacts u2014 in particular undesirable ones the present invention does this by overlaying smaller higher spatial frequency microstructures on top of lower frequency ones by either of the following performing a first exposure with larger microstructure projections about 5 100 microns upon a target substrate coated with photoresist recording media followed by a second exposure with smaller microstructures about 0 5 3 microns projected upon the same substrate i e on top of the larger microstructures the photoresist can be either developed or left undeveloped between these two exposures placing a partial mirror between the mid diffuser and the target substrate coated with photoresist recording media with the partial mirror close less than 4 inches and preferably 0 25 inches to 3 inches to the target substrate so as to produce a substantial i e recordable re reflection of the part of the original recording light that is reflected from the recording media referring to fig3 the present invention is retrofittable to existing equipment 300 used to fabricate planar holographic optical diffuser masters by introducing.