We report the design and performance of narrowband transmission filters employing the rapidly changing extinction coefficient that is characteristic of BaF2 and SiO2 films within certain wavelength intervals in the vacuum ultraviolet. We demonstrate the design concept for two filters centered at 135 nm for BaF2 and at 141 nm for SiO2. It is found that these filters provide excellent narrowband spectral performance when combined with narrowband reflection filters. The filter centered at 135 nm has a peak transmittance of 24% and a bandwidth of 4 nm at full width at half-maximum for collimated incident light. The transmittance for λ0 ≤ 130 nm is <0.1% and for 138 ≤ λ0 ≤ 230 nm the average transmittance is <3%. Another filter centered at 141 nm has a peak transmittance of 25% and a bandwidth of 3.5 nm.
Muamer Zukic, Douglas G. Torr, James F. Spann, and Marsha R. Torr, "Vacuum ultraviolet thin films. 2: Vacuum ultraviolet all-dielectric narrowband filters," Appl. Opt. 29, 4293-4302 (1990)