In recent years, much progress has been made on the development of metal mirrors based on additive manufacturing (AM). The sandwich mirror is well known for its excellent mechanical properties and challenging machining. Now, AM can be used to fabricate this complex structure and reduce the processing time and cost. In addition, with the aid of some new design methods for additive manufacturing, such as lattice, topology optimization (TO), and Voronoi, the freedom of mirror structure design is enormously improved. The common materials of mirrors include ceramics (SiC), glasses (glass ceramics, fused silica), and metals (aluminum, beryllium). Among them, the AM technology of metals is the most mature and widely used. Researchers have recently extensively developed the new-generation metal mirror to improve performance and lightweight rate. This review focuses on the following topics: (1) AM technologies and powder materials for metal mirrors, (2) recent advances in optomechanical design methods for AM metal mirrors, (3) challenges faced by AM metal mirrors in fabricating, and (4) future trends in AM metal mirrors.

Additive manufacturing (AM)—layer-by-layer printing—completely changes the conventional manufacturing method. The design freedom for mirrors is increased without the limits of the manufacturing process. Advanced lightweight mirrors (ALM), new-type mirrors designed using the generative method and lattice technologies, have emerged as the times require. Contrasting with conventional lightweight mirrors (CLM), the performances of ALM are drastically improved. This paper took the Voronoi mirrors as an ALM case study and introduced a design flow. In addition, a conventional honeycomb mirror was designed using the analytical method as the control. The optomechanical performances of the two were further compared through finite element analysis (FEA). Finally, ALM’s optomechanical performances outperformed CLM’s, including the area density, structural stiffness, surface stability, and quilting deflection.

Microsatellites have a great attraction to researchers due to their high reliability, resource utilization, low cost, and compact size. As the core component of the optical payload, the mirror directly affects the system package size. Therefore, the structural design of mirrors is critical in the compact internal space of microsatellites. This study proposes a closed-back mirror with composite surfaces based on additive manufacturing (AM). Compared with the open-back mirror, it provides excellent optomechanical performance. In addition, AM significantly reduces the intricate mechanical parts’ manufacturing difficulty. Finally, the roughness was better than 2 nm. The surface shape of the AM aluminum mirror reached RMS 1/10λ (λ = 632.8 nm) with the aid of ultra-precision machining technologies such as single-point diamond turning (SPDT), surface modification, and polishing, and the maximum deviation of the surface shape was about RMS 1/42λ (λ = 632.8 nm) after the thermal cycle test, which verified the optical grade application of AM.

Since the atmosphere has a strong scattering effect on ultraviolet light, the transmission of non-line-of-sight (NLOS) signals can be realized in the atmosphere. In previous articles, ultraviolet (UV) light atmospheric scattering has been characterized by many scattering models based on spot light sources with uniformly distributed light intensity. In order to explore the role of light sources in atmospheric transmission, this work proposed a UV light atmospheric transport model under different types of light source, including light-emitting diode (LED), laser, and ordinary light sources, based on the Monte Carlo point probability method. The simulation of the light source in the proposed model is a departure from the use of a light source with uniform intensity distribution in previous articles. The atmospheric transmission efficiency of different light sources was calculated and compared with the data of existing models. The simulation results showed that the type of light source can significantly change the shape of the received signal and the received energy density. The Monte Carlo (MC) point probability method dramatically reduced the calculation time and the number of photons. The transmission characteristics of different ultraviolet light sources in the atmosphere provide a theoretical foundation for the design of ultraviolet detection and near-ultraviolet signal communication in the future.

A novel multiregion structure apodized photon sieve is proposed. The number of regions, the apodization window values, and pinhole sizes of each pinhole ring are all optimized to enhance the energy efficiency and enlarge the pinhole sizes. The design theory and principle are thoroughly proposed and discussed. Two numerically designed apodized photon sieves with the same diameter are given as examples. Comparisons have shown that the multiregion apodized photon sieve has a 25.5% higher energy efficiency and the minimum pinhole size is enlarged by 27.5%. Meanwhile, the two apodized photon sieves have the same form of normalized intensity distribution at the focal plane. This method could improve the flexibility of the design and the fabrication the apodized photon sieve.

In this paper, we investigate the relationship between open-ring zones of the Fresnel zone plate and the pinhole rings of photon sieves (PSs). Numerical simulations show that the normalized diffraction fields near the focal point of an individual pinhole ring and the circular open-ring zone are the same. It is confirmed that the maximum diffraction efficiency of an open-ring zone is higher than that of the traditional pinhole ring. Meanwhile, pinhole rings have more flexibility for apodization filtering. Based on these key findings, we propose the design theory of an apodized diffractive optical element comprised of open-ring zones and pinholes. To validate the theory, we developed a design example. Compared with traditional apodized PSs, the new apodized diffractive element has a 50.19% higher energy efficiency, and the minimum pinhole size is enlarged by 30.77%.