空间大口径望远镜紫外到长波红外超宽谱段高反射膜研究

目前空间望远镜正朝着大口径、宽工作谱段方向发展，口径越大分辨率就越高，谱段越宽获得的信息就越丰富，大口径宽谱段则意味着空间望远镜能够看得更清、更远、更多。由于大口径空间望远镜光学系统多采用反射式结构，反射镜表面的反射膜决定了其工作谱段。虽然金属膜具有宽谱段高反射、可低温镀制等优点，是大口径空间反射膜的首选，但是无法实现从紫外到长波红外超宽谱段内高反射。本项目提出薄银膜/厚铝膜双层金属膜和紫外反射增强多层介质膜组成的复合膜系结构设计思想，设计出从紫外（250纳米）到长波红外（12微米）超宽谱段内都具有高反射率的反射膜。并采用大口径（直径2.5米）镀膜设备研究复合膜系结构低温镀膜工艺，实验上获得从紫外到长波红外超宽谱段内的高反膜。本项目还将研究连接层对膜层牢固度的影响以及复合多层膜的抗环境能力，获得满足空间环境应用的复合多层膜，为实现我国空间大口径超宽谱段反射镜镀膜提供设计思想和关键技术储备。

Now space-based telescope is developing toward large aperture and wide working band. The larger the aperture is, the higher the resolution becomes. The wider the working band is, the more abundant information telescope can get. Therefore, large aperture and wide working band mean that space-based telescope can observe more abundant objects under a higher resolution. Because most of the optical systems of space-based large-aperture telescope adopt reflecting configuration, reflecting films coated on mirror substrate determine the working band of telescopes. Metal films are the preferred materials for space-based large-aperture reflecting film coating due to their merits such as high reflection in wideband spectra and low-temperature coating process. However, metal films cannot realize a high reflection in an ultra-wideband spectra from ultraviolet (UV) to long-wavelength infrared (LWIR) region. In this project we propose a design concept of double metal films consisted of thin silver films and thick aluminum films, and multiple UV reflecting-enhanced dielectric films, by which an ultra-wideband optical reflector from UV (250nm) to LWIR (12um) can be achieved through a theoretical design. We will investigate the low-temperature coating processes of proposed compound film structures by using a large-size (2.5m diameter) coating machine, and attempt to prepare the compound films with a high reflection in an ultra-wideband spectra. Furthermore, we will explore the influence of adhesion and protection layers, and promote the environment durability of coated compound films to satisfy the applications under space environment. This project is promising to provide both design concept and key technical reserve for realizing space-based large-aperture and ultra-wideband reflecting film coatings.