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：To improve the resistance of long wave infrared (LWIR) band antireflective films on Ge in harsh environments, film design and fabrication technology have been discussed using LaF 3 as a low refractive index material. We fabricated high-performance multilayer antireflection (AR) coatings in an LWIR band (8-12 m) via an optimized film structure and sectional preparation of LaF 3 layer on Ge substrate. The peak transmittance was 98.3%, and the average transmittance increased from 48.4% to 96.2% when double-sided coating was used. This LWIR AR coating with LaF 3 passed various environmental, durability, and mechanical properties tests while maintaining good optical properties. Key words：LaF 3 ，long wave infrared band，high performance antireflective film