Preparation Of The Film Filter With Properties Of Combining Multi-wavelength Laser Beam

The optical film is an important part of optical elements, but film itself is easily fragile and prone to be damaged under high power laser. For high-power and high-energy laser systems, the laser damage resistance ability of films is always one of the bottlenecks of the development of the systems. So, the design and preparation of the thin film are particularly important. As a result, a kind of color laser film is designed and prepared in this thesis, which is applied in the laser damage of the system.In this thesis, single-layer thin films such as TiO2 and SiO2 are prepared by thermal evaporation on K9 glass and double-side polishing substrate, and the process parameters during the preparation was investigated systematically. The experimental results show the best process of TiO2 thin films:2.3×10-3Pa of working vacuum degree,5mA of revolution feedback current and 145-150mA of beam; based on 1-on-1 damaged testing method, by image method and phase contrast microscopy method damage evaluation standard, the laser-damage threshold of the film were tested and the film were made laser pretreatment. The results showed that: LIDTTiO2=12.3J/cm2, LIDTSiO2,=16.4J/cm2, laser irradiation can improve the morphology of thin film, which enhances the thin film laser-damage resistance ability. When the laser energy is thin films of LIDT 60%, the improvement of film laser-induced damage capability is most obvious.The designed structure is G|(HL)8L|A, the multilayer laser films is designed at 532nm of high-reflection and 1064nm of high-transmission,with 565nm of the center wavelength, and were prepared by using Nan Guang Group ZZS500-2/G-box-type vacuum coating machine. Transmittance and damage threshold test were done for preparation films. The test results show that:the transmittance of the sample was 95.7% at 1064nm, the reflectance of the sample was 99.4% at 532nm, LIDT is 7.4J/cm2, which all meet the demand of design. In order to study better the damage properties of thin film, the research of pretreatment has been done, LIDT=7.5 J/cm2 after pretreatment, the film damage performance after pretreatment unincreased. Laser pretreatment can improve the laser-induced damage threshold of the films.