There has been significant progress in the research and development of Far Ultraviolet (FUV) thin film devices, driven by growing demands in astrophysics, geophysics, and other fields. However, most materials exhibit strong absorption in the FUV region, posing challenges for optical element design due to the limited material options. To address this issue, extensive research has been conducted on materials, structures, and fabrication processes.Aluminum (Al) mirrors are the primary components in FUV devices, and fluorides are commonly employed as protective layers to prevent Al from oxidizing. Al+LiF and Al+MgF? mirrors have already been used in space telescopes like Far Ultraviolet Spectroscopic Explorer (FUSE) and Hubble Space Telescope (HST). The influence of deposition rate, substrate temperature, and protective layer thickness on the performance of these mirrors has been investigated. High-performance Al+eLiF (enhanced LiF) and Al+eMgF? (enhanced MgF?) mirrors were prepared by QUJIADA M A et al. using a three-step deposition method, which is currently considered a reliable approach to enhance the reflectivity of Al mirrors effectively. The absorption edge of LiF is about 105 nm, making it the transparent material with the shortest absorption edge known in nature, and a commonly used material for FUV short-wavelength band protective layers. However, LiF is hygroscopic, leading to poor time stability in Al+LiF mirrors. ANGEL D W et al. suggested that MgF? could effectively slow down the aging of Al+LiF, which led to the development and validation of protected Al+LiF mirrors. Al+LiF+MgF? and Al+LiF+AlF? mirrors have significantly improved time stability compared to Al+LiF films.Fluoride materials known for their low absorption and high stability, such as MgF?, AlF?, and LaF?, have become prevalent in FUV reflective filters. By utilizing a multi-periodic dielectric structure with alternating high and low refractive index materials, (LaF?/MgF?)? reflective filters have been successfully fabricated, centered at wavelengths of 135.6 nm and 121.6 nm. Higher reflectivity and narrower bandwidths were achieved by optimizing the design and fabrication processes. The successful fabrication of narrowband mirrors, such as Al+LiF+SiC+LiF and Al+LiF+B?C, has achieved the goal of suppressing the H Lyman α line in the solar spectrum. Furthermore, based on the (Al/MgF?)? structure, a transmission filter with a central wavelength of 121.6 nm has been realized. Optimization of the design and fabrication processes holds the promise of achieving higher transmittance and narrower bandwidths.The optical constants of thin films are fundamental for characterizing their performance, but they vary significantly under different conditions, especially in the FUV region. Optical constants for materials in the FUV range are relatively scarce. Conventional measurement methods, such as photometry, least squares fitting, and Kramers-Kronig analysis, have yielded optical constants for certain materials, such as MgF?, LaF?, and others.Despite these advancements, significant limitations still exist in FUV materials, and research on thin-film devices remains insufficient. More systematic and in-depth investigations into precise thin-film fabrication and environmental stability are needed. The field of FUV thin films holds vast potential for future development. Future research will focus on exploring new materials, optimizing structures, and innovating fabrication processes to broaden their applications.New materials with features such as higher optical performance, greater environmental stability, and broader operating wavelengths are sought to overcome the limitations of current materials. Further optimization of deposition methods, such as incorporating Atomic Layer Deposition (ALD) technology and other advanced fabrication techniques, is to develop efficient and precise manufacturing processes, obtaining more accurate optical constants through extensive measurements and establishing a comprehensive database of FUV optical constants. The design of more rational multilayer structures utilizing the properties of different materials, coupled with precise characterization and control, achieves wider bandwidths and higher reflectivity mirrors. Conducting in-depth studies on the impact of various environmental conditions on performance and developing effective protective measures, thereby enhance both performance and stability.A more comprehensive regulating of thin-film optical properties can be achieved by continuously exploring new materials, optimizing structural designs, and innovating fabrication processes. This will provide more precise data and theoretical guidance for optical element design, enabling the fabrication of more efficient FUV optical elements and driving advancements in optical device technology. Driven by increasing demands for astronomical observation, FUV thin-film devices are poised for significant performance improvements. It is anticipated that FUV reflective thin films will find broader applications in fields such as space exploration, lithography, and medical diagnostics.