Zhang Xuejun, Hu Haixiang, Wang Xiaokun, Luo Xiao, Zhang Ge, Zhao Wenxing, Wang Xiaoyi, Liu Zhenyu, Xiong Ling, Qi Erhui, Cui Congcong, Wang Yanchao, Li Yingjie, Wang Xu, Li Longxiang, Bai Yang, Cheng Qiang, Zhang Zhiyu, Li Ruigang, Tang Wa, Zeng Xuefeng, Deng Weijie, Zhang Feng
Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 130033, Changchun, Jilin, China.
University of Chinese Academy of Sciences, 100049, Beijing, China.
Light Sci Appl. 2022 Oct 26;11(1):310. doi: 10.1038/s41377-022-00994-3.
In the process of manufacturing the world's largest silicon carbide (SiC) aspheric mirror, the primary difficulties are mirror blank preparation, asphere fabrication, and testing, as well as cladding and coating. Specifically, the challenges include the homogeneity of the complicated structure casting, accuracy and efficiency of the fabrication process, print-through effect, fidelity and precision of test procedure, stress and denseness of cladding process, the dynamic range of interferometric measurement, and air turbulence error due to the long optical path. To break through such a barrier of difficulties, we proposed the water-soluble room temperature vanishing mold and gel casting technology, homogeneous microstructure reaction-formed joint technology, nano-accuracy efficient compound fabrication, gravity unloading technology, high-denseness low-defect physical vapor deposition (PVD) Si-cladding technology, test data fusion method, and time-domain averaging method, etc. Based on the proposed technologies and methods, we have accomplished the world's largest SiC aspheric mirror with a size of ⌀4.03 m. The impressive performance of the SiC aspheric mirror is validated by the characteristics of the fabricated SiC aspheric mirror. The aerial density of the SiC blank is less than 120 kg/m, surface shape test accuracy is better than 6 nm RMS, thickness inhomogeneity of the cladding layer is less than 5%, and the final surface figure error and roughness are 15.2 nm RMS and 0.8 nm RMS, respectively.
在制造世界上最大的碳化硅（SiC）非球面镜的过程中，主要困难在于镜坯制备、非球面加工、测试以及包层和镀膜。具体而言，挑战包括复杂结构铸造的均匀性、制造过程的精度和效率、透印效应、测试程序的保真度和精度、包层过程的应力和致密性、干涉测量的动态范围以及由于光程长导致的空气湍流误差。为突破这些困难障碍，我们提出了水溶性室温消失模和凝胶铸造技术、均匀微观结构反应成型连接技术、纳米精度高效复合加工、重力卸载技术、高密度低缺陷物理气相沉积（PVD）硅包层技术、测试数据融合方法和时域平均方法等。基于所提出的技术和方法，我们完成了尺寸为⌀4.03 m的世界上最大的SiC非球面镜。所制造的SiC非球面镜的特性验证了其令人印象深刻的性能。SiC镜坯的面密度小于120 kg/m，表面形状测试精度优于6 nm RMS，包层厚度不均匀性小于5%，最终表面面形误差和粗糙度分别为15.2 nm RMS和0.8 nm RMS。
