Optimization Design & Technical Study On Antireflection Coating System

The design, optimization and growth technics of antireflection coatings were systematically studied in this paper. Using the simplex method, the antireflection coatings based on K9 glass were designed by a computer program. Growth parameters on the monolayer SiO₂ and Ta₂O₅ coatings were studied, and the multi-layer SiO₂/Ta₂O₅ antireflection coatings with high transmittance in visible light wave band were gained.In the first part of the paper, the application and develop status of antireflection coatings were analysed.In the design of multi-layer coating system, according to the theory of optical thin film, it had been given all design results of multi-layer antireflection coatings and corresponding spectrum characteristic curves, using advanced computer language MATLAB. In order to improve the antireflection effect, the author optimized multi-layer system by simplex method. As a result, a multi-layer antireflection coating system with higher transmittance was gained, whose theorial transmittance could universally reach 99% in visible light band. According to optimized theorial coating system, the specimen was produced and the optical transmittance could be over 96%⁹7%.According to the optimized results, K9 glass whose n=1.52 was selected as substrate. SiO₂/Ta₂O₅ multi-layer coatings were deposited by RF reactive magnetron sputtering. Influence of deposition parameters on monolayer SiO₂ and Ta₂O₅ were studied, respectively, on which that deposition of multi-layer coatings were based.In the technical research, the influence of various growth parameters, including oxygen content, substrate temperature, work pressure, etc., on the optical properties and structures of the coatings were studied. The deposition rates of monolayer SiO₂ and Ta₂O₅ were gained, respectively. The results showed that oxygen content strongly affected the refractive index of the film: the film grown in the Ar/O₂ sputtering gaseous mixture of oxygen content higher than 13% had steady refractive index used in design, while over 80% in Ta₂O₅ film growth.