锗和一氧化硅是中波红外区域通常使用的薄膜材料, 研究这些材料的特性, 找到最佳制备工艺并拟合出材料的光学常数, 是设计制备中波红外光学薄膜的关键。最佳工艺条件下, 选用以上两种材料, 以蓝宝石为基底, 设计并制备出中心波长为3.5 μm, 相对带宽4.8%的三腔带通滤光片, 其通带透过率可达80%。经光谱测试和环境可靠性实验结果表明, 该中波红外带通滤光片满足工程使用要求。

Germanium and silicon monoxide are two kinds of optical thin film materials used frequently in medium-wave infrared band. Study on their optical properties is the key to design and fabricate medium-band thin film. Germanium and silicon monoxide are selected as high and low refractive index materials respectively and the substrate is synthetic sapphire. Triple cavity band-pass filter of which the center wavelength is 3.5 μm, relative bandwidth is 4.8%, and transmittance of pass-band is about 80%, was designed and fabricated. Spectrum measurement and environment reliability experiment show that the infrared band-pass filter is competent for engineering application.