Study Of Deep Ultraviolet To Near-Infrared Broadband Anti-Reflective Coating

With the deeply serious problem of atmospheric environmental pollution,it is very important to accurately monitor and obtain the information of environmental components.At present,spectral detection technology is an effective method of atmospheric detection,and develops towards various band fusion and multi-field application.The requirements of detection accuracy and response sensitivity of spectral detectors are stringent.As the key component of the ultraviolet-infrared integrated detector,the high performance optical thin film is an important guarantee to realize the function.In this paper,a broadband from deep ultraviolet to near infrared antireflective coating was developed.According to the optical properties,physical and mechanical properties and refractive index matching of the material,coating materials and substrates were selected reasonably.Al2O3 and AlF3 were selected as high and low refractive index materials,and JGS1 as substrate.Based on the design theory of antireflective coating,the relationship between the initial iteration times and the average transmittance was analyzed by using the design software,and the iteration times were selected logically.On the basis of tolerance evaluation,the requirements of coating thickness and spectral performance were considered,and a new evaluation function was established.A combination of variable-scale method and tunnel method was adopted.By changing the thickness of the sensitive layer,the problem of thin layer in the coating structure could be solved and the difficulty of preparation could be reduced.In the coating preparation process,the electron beam evaporation process was optimized to study the effect of spectral properties and refractive index of the materials by ion source working gas.The quartz crystal monitor system was selected to monitor the coating thickness,and the coating thickness was modified under different process conditions to study the high temperature annealing technology.The method could improve the coating aggregation density,stoichiometric ratio and the coating stability.The reverse inversion analysis based the measured spectral curve results,the cause of the spectral curve deviation was analyzed,the thickness of high sensitivity layer was modified alone,and the impact of residual evaporation was reduced on the spectrum.The causes of absorption was analyzed in the deep ultraviolet range,the actual preparation results of different iterations were compared,and the process parameter was determined ultimately.According to the spectral test,in the 200~900nm band,the average transmittance of the double-sided thin coating was 95.8%,which achieved broadband effect of anti-reflection.After environmental testing,the coating performance was stable and meet the requirements for use.