车载主动式红外夜视系统中带通滤光膜工艺研究
Fabrication of Thin Film Band-Pass Filter for Automotive Active Infrared Night Vision System
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摘要: 在车载主动式红外夜视系统中, 为满足光学系统对滤光膜的要求, 提出一种800~1000 nm带通滤光膜, 以实现夜间大视觉范围、降低背景中杂散光干扰以及提高成像质量的要求。针对车载主动式红外夜视系统中带通滤光膜的参数要求, 以薄膜材料应用技术为基础, 优化、设计带通滤光膜系结构。采用OTFC-1300镀膜机制备薄膜, 建立评价函数, 通过牛顿迭代法优化薄膜结构, 调节敏感膜层厚度, 优化工艺, 解决了实际镀制的薄膜通带中心区域透过率低, 以及光谱曲线边缘起伏震荡大的问题, 最终制作了光学性能好的滤光膜。测试表明:在800~1000 nm波段平均透过率大于99%, 在380~780 nm波段平均透过率小于3%, 在1064~1270 nm波段平均透过率小于2%, 该滤光膜可以满足车载主动式红外夜视系统环境使用要求。Abstract: We reported the fabrication of thin film band-pass filter (800~1000 nm) for automotive active infrared night vision system.First, the thin films, comprising the low/high index SiO2/Ta2O5 multi-layers and designed with software Macleod, were deposited on quartz substrate in OTFC-1300 reactor under the optimized deposition conditions.Next, the influence of the precision of films' thickness on the filter's transmittance was investigated in Newton iteration algorithm with MATLAB software and by experimentally evaluation.Two major problems, including low transmittance at band-pass center and large concussion on both spectral edges, were solved by optimizing the thickness of sensitive layers.Finally, the prototyped filter, fabricated with the optimized layer thickness, was experimentally tested.The results show that the band-pass filter meets the environmental requirements.For instance, its properties included:a transmittance over 99% in 800~1000 nm range, an average reflectance below 3% (2%) in 380~780 nm (1064~1270 nm) range.