Design And Preparation Of Grid Films On Infrared Substrates With Metal Materials

At present,almost all optical element surfaces need to be plated with various films to improve their optical performance.In some optical systems,it is necessary to achieve efficient transmission of infrared signals in specific bands and good shielding of electromagnetic signals in certain frequency bands.Based on the principle theory of optical films and the electromagnetic shielding properties of metal mesh films,the paper aims to meet the actual demand by designing and preparing high-efficiency anti-reflection coatings in the 3?5?m infrared band.A metal mesh film with a certain electromagnetic shielding effectiveness in the12?18 GHz band was studied.By optimizing the infrared antireflection film system and the metal mesh structure,an electromagnetic shielding-compatible infrared antireflection film capable of efficiently infiltrating the infrared and effectively blocking electromagnetic interference was prepared on the double-sided polished Si substrate.The CST STUDIO SUITE electromagnetic simulation software was used to design and simulate grid structures with various line widths and periodic structures.The influence of the structural parameters of the metal mesh film on the electromagnetic shielding effectiveness in the 2?18 GHz band was analyzed.Metal mesh microstructures with different structural parameters were prepared on double-sided polished Si substrates by using photolithography mask and vacuum thermal evaporation and deposition.Metal mesh films whose plating cycle on silicon substrates is g=550?m and line width 2a=30?m were obtained.The electromagnetic shielding effectiveness of it is SE?12 d B.And the overall electromagnetic shielding effectiveness of metal meshes prepared on two Si substrates of different resistivity is compared and studied.After the optimization,the overall electromagnetic shielding effectiveness is better than 28 d B and reaches 28.6 d B at 15 GHz.The Zn Se and Ba F₂films were prepared on single-sided polished silicon by using ion beam assisted thermal evaporation deposition technology,and the preparation process and optical constants of the films were obtained.Based on the optical film theory,TFCale,the film system simulation software,was used to design an efficient anti-reflection infrared film within3?5?m,whose film structure is S|3.5H3.5L|A and the designed wavelength is 1064 nm.Meanwhile,vacuum thermal evaporation with ion beam assisting is used.Finally,the sample of infrared anti-reflection film was prepared with the peak transmittance and average transmittance reaching 99.8%and 99.3%respectively within 3?5?m.In order to further improve the transmittance of the metal mesh,an infrared antireflection film was deposited on the metal mesh film with a periodic structure of g=550?m and a line width of 2a=30?m.Finally,an infrared anti-reflection film was prepared with its overall electromagnetic shielding effectiveness in the band of 12?18 GHz greater than 28 d B.Within3?5?m,its peak transmittance reaches 86.3%,and the average transmittance 86.1%.