Diffraction efficiency control in holographic elements.

摘要

A method for precisely controlling the diffraction efficiency of a hologram including the steps of (a) defining a mask having opaque and transparent areas wherein the proportion of the opaque areas relative to the transparent areas is selected pursuant to the desired diffraction efficiency, the opaque and transparent areas being sufficiently small so as to have little noticeable effect when the resulting hologram is played back, (b) applying the mask to a hologram recording medium, (c) exposing the hologram recording medium to non-coherent illumination whereby only the areas exposed by the apertures are exposed to the non-coherent illumination, (d) removing the mask, and (e) exposing the hologram recording medium to hologram forming illumination at an effective exposure that yields maximum hologram efficiency. Such effective exposure can be in the saturated region of the efficiency vs. exposure curve wherein changes in efficiency as a function of parameter variation are small. <IMAGE>