Abstract: An optical filter (10) has a radiation receiving surface, the filter including a rugate reflection filter having a reflection wavelength characteristic varies along an axis of the radiation receiving surface. The optical filter includes a plurality of serially disposed rugate coatings (10b, 10c) and has a wavelength rejection gradient that exhibits a linear, logarithmic, or power function of wavelength rejection as a function of position on the radiation receiving surface. Two or more rugate subfilms may overlap one another, or none of the rugate subfilms may overlap. The filter has a first optical density associated with a first one of the subfilms, a second optical density associated with a second one of the subfilms, and, for overlapping spectral ranges, a third optical density within a region wherein at least two subfilms overlap one another. The third optical density is a summation of the first optical density and the second optical density.