# Design and Fabrication Technology of Metal Mirrors Based on Additive Manufacturing: A Review
[PERSON]  
1 Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China; [EMAIL_ADDRESS] (K.Z. ); [EMAIL_ADDRESS] (H.Q. ); [EMAIL_ADDRESS] (H.G. ); [EMAIL_ADDRESS] (X.Z. ); [EMAIL_ADDRESS] (X.X. ); [EMAIL_ADDRESS] (L.Y. ); [EMAIL_ADDRESS] (C.W.) [PERSON]  
1 Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China; [EMAIL_ADDRESS] (K.Z. ); [EMAIL_ADDRESS] (H.Q. ); [EMAIL_ADDRESS] (H.G. ); [EMAIL_ADDRESS] (X.Z. ); [EMAIL_ADDRESS] (X.X. ); [EMAIL_ADDRESS] (L.Y. ); [EMAIL_ADDRESS] (C.W.) [PERSON]  
1 Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China; [EMAIL_ADDRESS] (K.Z. ); [EMAIL_ADDRESS] (H.Q. ); [EMAIL_ADDRESS] (H.G. ); [EMAIL_ADDRESS] (X.Z. ); [EMAIL_ADDRESS] (X.X. ); [EMAIL_ADDRESS] (L.Y. ); [EMAIL_ADDRESS] (C.W.) [PERSON]  
1 Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China; [EMAIL_ADDRESS] (K.Z. ); [EMAIL_ADDRESS] (H.Q. ); [EMAIL_ADDRESS] (H.G. ); [EMAIL_ADDRESS] (X.Z. ); [EMAIL_ADDRESS] (C.X.X. ); [EMAIL_ADDRESS] (L.Y. ); [EMAIL_ADDRESS] (C.W.) [PERSON]  
1 Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China; [EMAIL_ADDRESS] (K.Z. ); [EMAIL_ADDRESS] (H.Q. ); [EMAIL_ADDRESS] (H.G. ); [EMAIL_ADDRESS] (X.Z. ); [EMAIL_ADDRESS] (X.X. ); [EMAIL_ADDRESS] (L.Y. ); [EMAIL_ADDRESS] (C.W.) [PERSON]  
1 Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China; [EMAIL_ADDRESS] (K.Z. ); [EMAIL_ADDRESS] (H.Q. ); [EMAIL_ADDRESS] (H.G. ); [EMAIL_ADDRESS] (X.Z. ); [EMAIL_ADDRESS] (X.X. ); [EMAIL_ADDRESS] (L.Y. ); [EMAIL_ADDRESS] (C.W.) [PERSON]  
1 Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China; [EMAIL_ADDRESS] (K.Z. ); [EMAIL_ADDRESS] (H.Q. ); [EMAIL_ADDRESS] (H.G. ); [EMAIL_ADDRESS] (X.Z. ); [EMAIL_ADDRESS] (C.X. ); [EMAIL_ADDRESS] (L.Y. ); [EMAIL_ADDRESS] (C.W.) [PERSON]  
1 Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China; [EMAIL_ADDRESS] (K.Z. ); [EMAIL_ADDRESS] the optical accuracy range [6; 7; 8; 9; 10; 11; 12]. Currently, beryllium and aluminum are two kinds of materials that are widely used in metal mirrors. The 6.6 m aperture primary mirror of the James Webb Space Telescope (JWST) consists of 18 beryllium sub mirrors [13], and the Widefield Infrared Survey Explorer (WISE) [14; 15] adopts an all-aluminum design scheme, with aluminum mirrors mounted to an aluminum structure, as shown in Figure 1. Furthermore, a lot of research has been done to develop metal mirrors with a lighter weight and better structural rigidity to meet the requirements of optical systems. The variants of lightweight mirror design include arched mirrors, open-back mirrors, and sandwich mirrors (Figure 2) [16; 17; 18; 19]. [PERSON] found that the sandwich mirror has the best mirror efficiency in 1989 (Figure 3). The mirror efficiency is defined as the total mirror height divided by the mechanical deflection; a high efficiency is desirable [20]. However, the high-precision welding techniques adopted in the fabricating process of metal sandwich mirrors greatly raises costs and risks. In recent years, AM technologies for metal fabrication have been developed rapidly. It provides an effective way to reduce the difficulty of manufacturing complex structures [16]. AM can offer a complete process chain (Figure 4) for the direct production of these complex lightweight mirrors such as sandwich mirrors [21; 22].