Significance In high-power infrared laser systems, monocrystalline silicon reflectors are widely used, and the reflectors need to achieve high-precision, high-stability beam transmission under high-power laser irradiation for long durations. The high accuracy of components and laser load capacity are both highly desired. With the continuous development of high-energy laser technology, the performance of existing monocrystalline silicon components has been unable to support the further improvement of system output power and performance, which has become a technical shortcoming. A high-energy laser system requires optimum reflector performance in systems, i.e., precision and laser load capacity. The pursuit of full-frequency spatial error restraint and reduction of laser energy absorption rate depends on fabrication quality. However, at present, fabrication technology inherits from traditional optical processing, and it is difficult to achieve both precision and laser load capability. Accordingly, it is necessary to investigate manufacturing methods and processes and combine innovative manufacturing techniques with application characteristics. By discussing the present situation and key technology of monocrystalline silicon component manufacturing, we hope technical support for realizing nanoprecision shape control manufacturing of monocrystalline silicon can be provided.

Progress This article summarizes the current status of and difficulties in manufacturing high-energy laser aspheric components and reveals the typical processing defect morphology and generation mechanism that reduce the laser load capacity. Based on the realization of high-precision processing of aspherical components, the role of new methods of controllable flexible body processing based on immersion smooth polishing, ion beam sputtering cleaning, and other methods in controlling defects is discussed to realize the formation of high-energy laser aspherical components. The specific research includes the following aspects:

(1) Nanoprecision surface shape control manufacturing technology. With continuous improvement in energy transmission ratio and irradiation distance of laser systems, the quality of optical parts has also increased. Nanoprecision manufacturing requires the full-frequency band error to converge to the nanometer order of magnitude. At this time, the surface shape error and the medium- and high-frequency roughness at the macroscopic scale will be in the same order of magnitude, and the correlation between them will be obviously enhanced. In recent years, our research group has vigorously developed ultraprecision cutting (Fig.1), magnetorheological methods (Fig.2), ion beam techniques, and cylindrical smoothing techniques (Fig.3) to obtain full-band subnanoprecision optical surfaces.

(2) Nanoprecision intrinsic surface controllability generation method. The surface of monocrystalline silicon generally leads to some typical damage precursors such as absorbable impurities, cracks, and scratches during mechanical polishing. The types and densities of these damage precursors seriously restrict the damage resistance of optical components. As a new form of subsurface defect, the body before nanodamage can be divided into mechanical, pollution, and structure types. Our research group has conducted a series of investigations on the monocrystalline silicon intrinsic surface processing method and the craft. It removes the optical component surface defect (Fig.5) and obtains the nanoprecision intrinsic surface through immersion polishing (Fig.4) and ion beam technology (Fig.6 and Fig.7), which enhances the loading ability of monocrystalline silicon.

(3) Nanoprecision shape control combination process. To achieve the goal of nanoprecision surface shape control, our research group has realized a combination process of high precision and low defect (Fig.8), which is different from the simple connection conversion of traditional machining processes. The combined process reasonably distributes all the indexes to the entire process and realizes the high-precision and low-defect control manufacturing of monocrystalline silicon components (Fig.11). Immersion smooth, ion beam modification, and postprocessing are used to optimize the defect restraint strategy and develop monocrystalline silicon substrates. Compared with the traditional process, the advantages of the combined process in improving the accuracy, reducing the absorption, and achieving good adaptability on paraboloid and cylindrical elements are verified. Full-frequency subnanoscale-accuracy manufacturing is realized on small-diameter planar components. Full-band error convergence and absorption precursor restraint are realized on large-aperture planar, parabolic, and cylindrical components and high-precision, low-absorption, and high-power laser monocrystalline silicon is processed component substrate.

Conclusion and Prospect The main achievements of high-precision and low-defect control manufacturing technology in the Precision Engineering Laboratory of National University of Defense Technology in recent years are reviewed. The high-precision and low-defect combination processing technology developed by our research group has been applied to the processing of monocrystalline silicon, which supports the development of high-power laser systems.