金刚石因其卓越的力学、热学和光学性能，被认为是高功率激光器输出窗口和红外光学窗口等领域的理想材料，然而金刚石较高的表面反射损耗限制了其作为光学材料的应用范围。在金刚石表面镀制增透膜和构造减反射微结构是提高金刚石透过率的2种有效方法。首先，介绍了2种金刚石增透方法的基本原理，金刚石表面增透膜方法可以通过调整膜的成分、厚度和结构等，使金刚石表面的反射光相互干涉抵消，达到减反射的效果;减反射微结构通过在金刚石表面形成亚波长微结构，无法分辨入射光，其结构层可等效为折射率渐变的薄膜，可减少折射率突变引起的反射，实现增透。然后，重点综述了近年来金刚石表面增透膜和减反射微结构等技术的研究进展，详细阐述了单层、双层、多层增透膜及减反射微结构对金刚石实际透过率的影响规律，分析了不同增透技术的影响因素，其中增透膜的材料和结构对增透效果的影响较大，微结构的增透效果主要取决于尺寸、周期和占空比。同时，总结了增透膜和微结构的各类制备技术特点，对比了2种增透技术的优缺点。最后，展望了金刚石表面增透膜和减反射微结构技术的应用前景和未来发展趋势。

With exceptional thermal conductivity, wear resistance, and chemical stability, diamond exhibits excellent optical transmittance across a broad spectrum from 0.3 to 2.5 μm and over 6 μm. Consequently, it is considered an ideal material for high-power laser output windows and infrared optical windows. However, due to the high refractive index (n=2.42), the surface reflection loss is high on diamonds, which leads to the actual transmittance of diamonds falling short of theoretical expectations. Therefore, the high surface reflection restricts the application and prevalence of diamond as an optical window material. Coating anti-reflection film and constructing anti-reflection microstructure on diamond surfaces are two effective methods to improve diamond transmittance. Firstly, the basic principles of the two diamond transmittance enhancement methods are introduced. The anti-reflection film on the diamond surface makes the reflected light on the diamond surface interfere and cancel each other by adjusting the composition, thickness, and structure of the film, to achieve the anti-reflection effect. On the other hand, the anti-reflection microstructure forms a subwavelength microstructure on the diamond surface, which can not be distinguished by incident light, and the structure layer can be equivalent to a graded refractive index film, which can reduce the reflection caused by the sudden change of refractive index and achieve anti-reflection effect. Then, the common preparation methods of anti-reflection film and anti-reflection microstructure on the diamond surface are described. The deposition methods of the anti-reflection film are classified into physical and chemical vapor deposition, mainly including evaporation, magnetron sputtering and chemical vapor deposition (CVD), and the preparation methods of anti-reflection microstructure include silicon replication, laser processing, and ion etching and the advantages and disadvantages of the above preparation methods are also summarized. Then, the research progress of the two transmittance enhancement methods is further discussed, and the transmittance enhancement effects of the two methods are reviewed. The effects of single-layer, double-layer, and multi-layer antireflection films and anti-reflection microstructure on the transmittance of diamonds are analyzed in detail. The single-layer anti-reflection film can achieve transmission in a fixed wavelength band, and the double-layer anti-reflection film can further enhance the transmittance in the target wavelength band, but the transmittance on both sides of the target wavelength band is not as effective as that of the single-layer film. The multi-layer anti-reflection film can achieve high transmittance, wide band transmission, and wide angle of incidence, and has the best anti-reflection effect, but with the increase of the number of layers, the problem of poor adhesion between the film systems becomes more and more serious, and the performance of multi-layer anti-reflection transmission film will be seriously limited. The anti-reflection microstructure also has the advantages of a good anti-reflection effect and wide anti-reflection band, but it is difficult to process and the actual optical transmittance is low. Therefore, increasing the adhesion between the multi-layer anti-reflection film system and accurately processing the designed anti-reflection microstructure will be key development directions in the future. At present, based on the anti-reflection film and anti-reflection microstructure technology, the optical transmittance of diamonds has been effectively improved, but many problems need to be solved to realize the practical application of diamonds in optical windows and other fields, including the preparation process, performance, durability, and damage resistance of anti-reflection film and anti-reflection microstructure, so the path to optimization is still challenging. Therefore, optimizing the preparation process, improving the adhesion and stability of the anti-reflection film system, and enhancing the actual transmittance of the anti-reflection microstructure are the key development trends of diamond anti-reflection research in the future.