Multilayer edge filter for the 3.2-4.9-microm range

The design and manufacture of a Ge/SiO multilayer edge filter matched to air by MgF(2) are presented. The design is based on the equivalent layers theory and numerical optimization of the analytical structure. The filter has an average transmission of 96% in the 3.2-4.9-microm region, and its rejection zone covers the visible and uv regions.