4m-order high-precision SiC aspheric mirror integrated manufacturing system has been accepted

[ China Instrument Network Instrument Development ] On August 21, 2018, the Conditional Support and Finance Bureau of the Chinese Academy of Sciences organized the acceptance meeting of the "4m high-precision SiC aspheric mirror integrated manufacturing system" project in Changchun. More than 50 people including Zheng Xiaonian, director of the Chinese Academy of Sciences, the relevant departments of the institution, the acceptance expert group, the user representative, the project supervision team, and the project research and development team attended the acceptance meeting.

4m diameter high precision silicon carbide aspheric mirror. Photography: Zhang Yixin

The National Major Scientific Research Equipment Development Project “The 4m High-Precision SiC Aspherical Mirror Integrated Manufacturing System” undertaken by the Changchun Institute of Optics and Fine Mechanics and Physics of the Chinese Academy of Sciences (hereinafter referred to as the Changchun Institute of Optics and Mechanics, Chinese Academy of Sciences) passed the project acceptance. The Changchun Institute of Optics and Fine Mechanics of the Chinese Academy of Sciences has completed the manufacture of high-precision silicon carbide (SiC) aspherical mirrors with a diameter of 4.03 meters (the largest reported in the public). Its core manufacturing equipment and manufacturing process have completely independent intellectual property rights. The successful development of this project marks the technical level of China's large-diameter silicon carbide aspheric optical mirror manufacturing field has been ranked first in the world.

Manufacturing is the mainstay of the national economy and the main battlefield for technological innovation. Since the reform and opening up, China's manufacturing industry has continued to develop rapidly, which has effectively promoted the process of industrialization and significantly enhanced its overall national strength. In recent years, the emergence of new technological trends in the future, disruptive technologies, emerged in an endless stream, will urge the major changes in the production industry, and become a breakthrough in the new leap in social productivity.

The large-caliber high-precision aspheric optical mirror is the core component of high-resolution spatial Earth observation, deep space exploration and astronomical observation system. Its manufacturing technology level is of great significance to a country's national defense security, national economic construction and basic scientific research capabilities. It is also an important indicator to measure the development level of a national high-performance optical system.

Silicon carbide ceramic materials are recognized as high-stability optical mirror materials in the international optical world. The use of silicon carbide materials can greatly improve the performance of large-caliber imaging systems. European and American countries have long been in a monopoly position in the manufacturing technology of large-diameter silicon carbide optical mirrors. There is a big gap between China's large-caliber optical manufacturing technology and the world's advanced level. It is extremely urgent to develop large-caliber silicon carbide optical manufacturing technology.

Facing the country's strategic demand for large-scale optical instruments, it is urgent to develop a "4m-scale high-precision silicon carbide aspheric mirror integrated manufacturing system with independent intellectual property rights". At the end of 2009, with the support of the Chinese Academy of Sciences and the Ministry of Finance, the Chinese Academy of Sciences Changchun The "4m-order high-precision SiC aspheric mirror integrated manufacturing system" project started by the optical machine, independently developed a large-caliber high-precision aspheric mirror manufacturing system, occupying the commanding heights of the international high-end manufacturing field, and will be towed through the project forward-looking layout. It has promoted a series of related technological developments in the country. The project research has important scientific value and clear application background, and is in line with the development strategy of the National Medium- and Long-Term Science and Technology Development Plan.

Under the leadership of researcher Zhang Xuejun, the project leader of Changchun Institute of Optics, Chinese Academy of Sciences, the project research and development team has completed eight years of technical research and completed the research and manufacturing process of manufacturing equipment for silicon carbide mirror blank preparation, aspheric surface processing and silicon carbide surface modification coating. The company has formed a "4m high-precision silicon carbide aspheric integrated manufacturing platform with independent intellectual property rights" and completed the development of 4m high-precision silicon carbide aspheric surface products based on the integrated manufacturing platform.

Large-diameter, high-precision silicon carbide aspheric mirrors are extremely difficult to manufacture. The main key technical bottlenecks are three aspects: silicon carbide material preparation, aspheric surface processing and high performance modified coating.

In the preparation technology of silicon carbide materials: Since the preparation process of large-diameter silicon carbide mirror blanks is accompanied by complex physical phase transitions and chemical reactions, it has been recognized internationally that 1.5 meters is a single silicon carbide reflection for a long time. The limit of the mirror. The project R&D team has gone through hundreds of experimental explorations and process validations, and has worked hard to break through the key technologies of series mirror blank preparation, established a large-diameter silicon carbide mirror blank manufacturing platform, and successfully developed 2m, 3m single silicon carbide mirrors. Billet, 4m diameter monolithic silicon carbide mirror blank (public report of the largest caliber), indicating that China has realized large-diameter silicon carbide optical materials have achieved independent controllable.

In the aspect of large-diameter silicon carbide aspheric processing technology: the first non-spherical CNC machining center successfully applied to high-precision manufacturing of large-diameter silicon carbide in China, breaking through the bottleneck of high-precision and high-efficiency processing technology of large-diameter silicon carbide aspheric surface, and solved The series restricts the key issues of high-precision detection of large-diameter aspheric surfaces. The high-precision machining of 4m-scale silicon carbide aspheric surface has been completed, and the machining accuracy is better than 20nm (RMS value). The high-precision machining and detection technology of 4m-scale silicon carbide is fully controllable.

In the aspect of large-diameter silicon carbide modified coating technology: the project R&D team has successfully developed an integrated SiC mirror modification and reflective film plating equipment for the first time, with 4m-level mirror modification and coating capability. In combination with the sputtering process, the technical problems of stress control, defect reduction and uniformity optimization of the modified layer were overcome. The surface modification of 4m-scale silicon carbide was completed by magnetron sputtering for the first time to meet the polishing requirements of high-quality optical surfaces. Through the multi-parameter combination optimization of the magnetron sputtering process, the high-reflectivity film coating on the surface of the 4m silicon carbide mirror is realized, and the full-wavelength reflectance of the long-wave infrared is better than 95%.

The successful development of "4m-order high-precision SiC aspheric mirror integrated manufacturing system" has broken the monopoly position of foreign large-aperture aspheric manufacturing technology and formed the development capability of 4m-scale large-caliber mirror with independent intellectual property rights. It has filled a number of domestic gaps and greatly improved the development level of high-performance large-scale optical instruments in China, with obvious direct economic and social benefits.

The acceptance expert group gave a high evaluation to the completion of the project. It believed that the project team completed the development of a 4m-order high-precision SiC aspheric mirror integrated manufacturing system, and all technical indicators met or exceeded the project approval requirements. The assessment indicators require that the system performance is internationally leading. This project is a major technological breakthrough in the field of large-caliber optical manufacturing in China, and has formed a large-diameter series of mirrors. The 1.5m caliber and 2m caliber SiC mirrors have been successfully applied to major national model tasks. The 4m caliber SiC mirror engineering products will soon be applied to the national large-scale photovoltaic system, and also solve the core technical problems for the development of space large-caliber optical systems.

The research results of the project will be applied to a series of major national engineering projects, which have important strategic significance for China's basic scientific research, disaster prevention and mitigation, public safety, and national security.

(Original title: National Major Scientific Research Equipment Development Project "4m-order high-precision SiC aspheric mirror integrated manufacturing system" passed the acceptance test)