Method of manufacturing a height-modulated optical diffractive grating

Abstract

The invention concerns a method of manufacturing a height-modulated optically diffractive grating. The method comprises providing a substrate and manufacturing a plurality of temporary elements of first material onto the substrate, the elements being separated by gaps and arranged as a periodic structure comprising at least two periods having different element heights. A coating layer of second material is deposited on the plurality of temporary elements such that the coating layer fills said gaps and covers said temporary elements. Then, a uniform layer of the second material is removed in order to expose said temporary elements and the first material is removed in order to form a height modulated pattern of the second material onto the substrate as the optically diffractive grating. The invention relaxes manufacturing constraints when manufacturing gratings with locally varying diffraction efficiency.

Dependencies are inferred from the claim text.