DESIGN OF ULTRAVIOLET NEUTRAL DENSITY FILTERS USING METAL-INSULATOR INHOMOGENEOUS LAYERS

We propose the use of metal-insulator films as neutral density filters for spectrophotometric calibration in the UV and visible ranges. We present a theoretical approach to the design of such filters and show that the correct selection of starting metallic material as well as filling fraction and filter thickness is important in obtaining the required profile. A comparison between theoretical and experimental Ni/SiO2 films show the suitability of this approach to designing neutral density filters for the 200-800-nm wavelength range and beyond.