US Patent 11391870 Height-modulated diffractive master plate and method of manufacturing thereof

The invention relates to a method of fabricating a master plate for producing diffractive structures and a master plate obtainable therewith. The method comprises providing a substrate having a periodic surface profile, filling the surface profile uniformly at least partly with filling material, and partially removing the filling material in order to produce a master plate having a periodic height-modulated surface profile formed by said substrate and said filling material. The invention allows for producing master plates capable of further producing gratings with variable diffraction efficiency.