In this letter, using mult-half-wave structure and some chosen films optimized method, the long-wave infrared (LWIR) narrow-band pass filter is investigated, meanwhile the opposite of the substrate coated with long-wavelength pass film. The transmittance of design spectrum is more than 80% at wavelength region of 8.05–8.35 \mu m, and the average transmittance is less than 0.5% at wavelength region of less than 7.95 and 8.45–14 \mu m. The filter is prepared by thermal evaporation method, and plas
