For many years, the development of the key component of large aperture telescopes - the large aperture reflector - has been a focus of competition among countries. The laboratory of the Advanced Manufacturing Center for Optical Systems of the Chinese Academy of Sciences, Chunguang Institute of Mechanical Mechanics, has now fully mastered the core technology of manufacturing large aperture mirrors, which has played an important role in promoting China's space exploration and development. A series of reports titled "Entering the Laboratory to See New Quality Productivity", today we enter the Key Laboratory of Advanced Manufacturing of Optical Systems to see how the largest "cornea" of China's "thousand mile eye" is manufactured. The reporter introduced that if an optical telescope is compared to the human "thousand mile eye", then the main reflector in the optical telescope can be called the "cornea". The larger the aperture of the primary reflector, the higher the spatial resolution of the optical telescope. Simply put, it means you can see more clearly. Now, among the global optical telescopes, the main mirror made of silicon carbide with the largest aperture was born in the laboratory of Chunguang Institute, President of Chinese Science. The giant silicon carbide reflector you are seeing now has a diameter of 4.03 meters. Assuming this reflector is installed on a space camera, even at altitudes of several hundred kilometers, it can clearly capture the outline of a car on the ground, including details such as the sunroof and rearview mirror. Large aperture optical reflectors are the core components of high-resolution space Earth observation, deep space exploration, and astronomical observation systems. Their manufacturing technology level is an important indicator of a country's development level of high-performance optical systems. The Key Laboratory of Advanced Manufacturing of Optical Systems has long been committed to the development of large aperture optical reflectors. Zhang Ge, deputy director of the Key Laboratory for Advanced Manufacturing of Optical Systems (Chinese Academy of Sciences) and researcher of Chunguang Institute of Mechanical Mechanics, president of Chinese Academy of Sciences, said that compared with traditional materials, silicon carbide has a specific stiffness of more than 4 times, so under the same deformation condition, its weight is only a quarter of that of traditional materials. In addition, its thermal conductivity is more than two orders of magnitude higher than that of traditional materials, greatly reducing its temperature control difficulty. However, although silicon carbide has excellent performance, it belongs to ceramic materials with high hardness. Once the diameter increases, it is easy to crack or even break during the billet making process. In the garden of Changchun Institute of Optics and Fine Mechanics, there is still an experimental mirror that used to be a large aperture reflector. Upon closer inspection, there are several hair sized cracks on it, which witness the repeated experimental processes of the research team. The preparation of mirror blanks is a crucial step in manufacturing silicon carbide reflectors. How did the research team achieve the transformation of micrometer sized silicon carbide powder into mirror blanks? Zhang Ge, deputy director of the Key Laboratory of Advanced Manufacturing of Optical Systems (Chinese Academy of Sciences) and researcher of Chunguang Institute of Mechanical Engineering, president of Chinese Academy of Sciences, introduced that this process is like making tofu at home. First, silicon carbide powder is put into water to form water-based slurry, then it is like making tofu bittern, and finally, various chemical reagents are added. This flowing slurry forms a gel, thus forming a lightweight structure that meets different scenarios and design needs. With a mirror blank, to become a true reflector, multiple processes such as optical processing, modification, and coating are required. In order to ensure the resolution and imaging quality of optical telescopes, optical systems have strict requirements for the surface shape accuracy of mirrors. For large aperture mirrors, the requirement for surface accuracy is even more extreme. At present, Zhang Ge, deputy director of the Key Laboratory for Advanced Manufacturing of Optical Systems (Chinese Academy of Sciences) and researcher of the Spring Institute of Machinery, President of the Chinese Academy of Sciences, introduced, for example, the manufacturing of a 4-meter aperture mirror, whose accuracy requirements reached 15 nanometers. If we make it on a small caliber, it is relatively easy, but for a large caliber like 4 meters, the difficulty is quite high. It's like leveling the ground within the 5th Ring Road in Beijing, where the ups and downs cannot exceed one millimeter. After more than 20 years of dedicated research, the laboratory's research team has broken through multiple key technologies in the manufacturing of large-diameter silicon carbide mirrors, achieving full chain manufacturing of large-diameter silicon carbide mirrors. At present, the large aperture silicon carbide reflector developed by the Key Laboratory of Advanced Manufacturing of Optical Systems has been applied to multiple major national engineering tasks. (New Society)