精密高效的脉冲波形调控是大型激光装置满足惯性约束聚变实验需求的重要技术之一。脉冲波形生成原理是通过编辑任意波形发生器中每个子脉冲的电压值，经电光调制器转换为光脉冲强度形成任意形状的激光脉冲轮廓。在电光转换过程中，各子束响应过程并非线性且子束间存在个性差异。为实现此条件下精密高效的脉冲波形调控，制定并开发了基于闭环迭代思路的激光脉冲波形快速调控方法。实验结果表明，算法可在10 min内实现任意脉冲波形整形，并具备23∶1高对比度脉冲波形调控能力，调控精度均优于10% (rms)，满足常规物理实验运行条件下对激光参数调控的精度和效率需求。

A recently proposed octahedral spherical hohlraum with six laser entrance holes (LEHs) is an attractive concept for an upgraded laser facility aiming at a predictable and reproducible fusion gain with a simple target design. However, with the laser energies available at present, LEH size can be a critical issue. Owing to the uncertainties in simulation results, the LEH size should be determined on the basis of experimental evidence. However, determination of LEH size of an ignition target at a small-scale laser facility poses difficulties. In this paper, we propose to use the prepulse of an ignition pulse to determine the LEH size for ignition-scale hohlraums via LEH closure behavior, and we present convincing evidence from multiple diagnostics at the SGIII facility with ignition-scale hohlraum, laser prepulse, and laser beam size. The LEH closure observed in our experiment is in agreement with data from the National Ignition Facility. The total LEH area of the octahedral hohlraum is found to be very close to that of a cylindrical hohlraum, thus successfully demonstrating the feasibility of the octahedral hohlraum in terms of laser energy, which is crucially important for sizing an ignition-scale octahedrally configured laser system. This work provides a novel way to determine the LEH size of an ignition target at a small-scale laser facility, and it can be applied to other hohlraum configurations for the indirect drive approach.

提出了基于激光脉冲波形精密调控和能量稳定性控制的双回路同步闭环设计方法，进而在任意波形发生器与预放大系统输出处建立脉冲波形闭环控制系统，在保偏大模场光纤放大器和再生放大器间建立能量稳定性闭环系统。依托大口径高通量实验平台，实现了激光脉冲波形的快速高稳定精密调控，脉冲波形闭环精度优于2%（RMS），脉冲能量稳定性优于5%（PV）。该技术成功应用到物理实验正式发射中，常规整形脉冲波形的功率准确度优于2%，相关结果有力支撑了ICF激光驱动器激光参数精密调控设计。

We propose a method for retrieving a beam wavefront from its near-field intensity distribution after a 4f system by simply inserting a benchmark at the Fourier plane. Through a convolution of the mark-blocked spatial frequency component and the original optical field with the 4f system, the separation between the focus of any sub-aperture and the benchmark can be determined to reconstruct the beam wavefront. Theoretical and experimental studies demonstrate the validity of this method, which has potential applications in real-time wavefront sensing.

在惯性约束聚变（ICF）领域，为了满足物理实验需求，需要采用短波长的紫外激光打靶。目前，国内外高功率固体激光装置普遍采用谐波转换的方式来获得三倍频紫外激光。高效的频率转换必须满足相位匹配条件，而晶体的反射面形畸变过大对准直精度和倍频效率均匀性都会产生不利影响。通过实验验证了晶体准直光斑的质量退化主要来源于晶体因夹持和重力导致的反射面形畸变，证明了改进晶体的夹持方式可以有效改善晶体面形，提高准直精度和准直光斑质量，并显著提升三倍频转换效率。

光束精密调控是惯性约束聚变(ICF)研究对激光驱动器的基本需求，它是一项装置层面的系统工程。主要介绍了中国工程物理研究院激光聚变研究中心近年来在靶面光强控制、脉冲波形控制、光束近场控制以及在新型光束探索方面所取得的重要进展。

Fifth harmonic generation (5th HG) of a Nd:glass laser is an effective way to acquire high-energy coherent deep-ultraviolet radiation near 200 nm. In this work, cascade generation of the fifth harmonic of a Nd:glass laser in a 5 mm ammonium dihydrogen phosphate (ADP) crystal was investigated, and maximum conversion efficiency of 14% and large angular acceptance of 45 mrad were demonstrated at a noncritical phase-matching temperature of 75.1°C. However, as the results reveal, the temperature sensitivity and nonlinear absorption would hinder its high-energy application. As for that, based on the complementary relationship of the angle and temperature in the phase-matching condition, an upgraded focusing 5th HG design coupled with the cylindrical temperature distribution scheme was proposed. By this upgraded focusing design, more than the improvement of the conversion efficiency, the output 5ω near-field intensity distribution turns out to be insensitive to the temperature gradient. Potentially, this idea can be applied for many other frequency conversion schemes such as high-repetition frequency lasers, which have similar temperature gradient problems.

Optics surface phase defects induced intensity modulation in high-power laser facility for inertial confinement fusion research is studied. Calculations and experiments reveal an exact mapping of the modulation patterns and the optics damage spot distributions from the surface phase defects. Origins are discussed during the processes of optics manufacturing and diagnostics, revealing potential improvements for future optics manufacturing techniques and diagnostic index, which is meaningful for fusion level laser facility construction and its operation safety.