基于LIGA技术的Wolter型空间X射线成像元件球面弯曲微缝光学的研制和性能研究

微孔光学（MPO）是目前有效面积质量比最大的X射线成像手段，是实现轻重量、大视场空间X射线探测的首选。而微缝光学（MSO）由弧形长缝阵列构成，相比正方形孔阵列的MPO结构上更适合在Wolter型聚焦光学上的应用。本项目使用LIGA技术并配合球面弯曲电镀技术，研制弯曲面形的MSO成像元件，并进行X射线反射率和平行光聚焦成像性能的测试分析。采用SU8胶线段阵列的独特工艺，制备大面积孤立胶结构阵列，配合弯曲电镀工艺，直接电镀成球面弯曲面形的金属镜片，避免后期对平片的压弯处理；利用离子束抛光技术对MSO微狭缝侧壁进行抛光，实现超光滑的目标；研究元件侧壁反光层材料、表面粗糙度、弯曲面形对X光反射率和聚焦斑形状、均匀性、集光效率等性能的影响，为提高成像质量提供技术优化方向与实验数据积累，评估现有LIGA技术可实现的MSO集光效率与探空需求的关系，并提高LIGA技术在X射线光学元件领域的加工能力

X-ray optics for planetary applications are so far prohibitive due to the mass constraint, since the space X-ray telescopes used for astrophysical missions include long and heavy parts as mirrors. Much effort has been put into light-weight and high-resolution X-ray optics exploration for such application. Micro-Pore Optics (MPO) as a form of X-ray optics with evident advantages attracts increasing interest in recent years. The sidewall surfaces of the micro-pore with very low roughness can be used as mirrors reflecting X-rays with a possible total external reflection due to the less-than-unity refractive index of X-ray, making it ideal for focusing application. Micro-Slot Optics (MSO) fabricated by LIGA technique has more advantages than MPO monopolized by foreign company in terms of fabrication technique in application of Wolter-type imaging optics. The most important parameters of a MSO mirror are the sidewall surface roughness and the aspect ratio of the micro-slot. Ion beam etching technique is chosen considering its non-contact polishing mode and the ability for removing materials in an atomic level. In order to improve the aspect ratio of the micro-slot of MSO, a new process is invented. SU8 segment array is used as cover layer which can fasten the PMMA columns together to prevent them from falling, which can basically improve the aspect ratio of the PMMA column array, resulting in the improvement of the micro-slot aspect ratio of MSO. Spherically curved MSO mirror is formed after electroforming process. Platinum coating on the sidewall of the MSO plate is explored using atomic layer deposition technique to increase X-ray reflection. The dependence of the X-ray imaging shape, uniformity and focusing efficiency on the material and the surface roughness of the mirror and the curvature will be studied, aiming at improving the imaging quality. The achievement of this project will accumulate experimental data for providing the direction for optimizing fabrication process and enhance the fabrication capacity of LIGA technique on the field in X-ray optics.