| Sapphire is an ideal material with excellent physical and chemical properties. However, with the infrared window to the high mach or higher mach, the strength of sapphire decreases dramatically at elevated temperature and the optical transmittance cannot satisfy the demand of application and design. In order to improve the high-temperature strength and transmittance, the best way is to coat the anti-reflective and protective films. Silicon dioxide (SiO2) are promising anti-reflective films with good physical,chemical properties and good adhesion to sapphire. Compared with the refractive of SiO2 films , Y2O3 has an higher refractive, and both of them can compose anti-reflective films. However, this subject has not been researched in domestic. This work researches are the design of anti-reflective films on sapphire, technical process of SiO2 and Y2O3 as a function of films structure and properties, and evaluation of SiO2 / Y2O3 films.With the help of Essential Macleod software, anti-reflective and protective films of SiO2 / Y2O3 films are designed on the sapphire substrate and analysis of structure sensitive factor and variation are done. The result of design explains that the average transmittance of SiO2 / Y2O3 films deposited on the surface of sapphire can exceed 99% in 35um waveband, which can meet the requirements of design and application of windows.The designed films of SiO2 / Y2O3 are prepared on sapphire by RF-refractive magnetron sputtering, and research the main technical parameters as a function of deposit speed. According to analysis technical parameters with Orthogonal design software, we will find out the technical parameter on the highest speed deposition.The prepared SiO2 and Y2O3 films are analysed by XPS, XRD, AFM, SEM,SE . The results show that Si, O, Y nearly compounds SiO2 and Y2O3 respectively and the deposited SiO2 films are amorphous compound. Y2O3 films are crystal compound which can transform during 600℃.The high temperature transmittance of both coated and uncoated sapphires is measured. The transmittance of coated films is improved. Micro-scratch test result shows that the interfacial adhesion of SiO2 / Y2O3 composite antireflective film is enhanced.
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