Elastography can be used as a diagnostic method for quantitative characterization of tissue hardness information and thus, differential changes in pathophysiological states of tissues. In this study, we propose a new method for shear wave elastography (SWE) based on laser-excited shear wave, called photoacoustic shear wave elastography (PASWE), which combines photoacoustic (PA) technology with ultrafast ultrasound imaging. By using a focused laser to excite shear waves and ultrafast ultrasonic imaging for detection, high-frequency excitation of shear waves and noncontact elastic imaging can be realized. The laser can stimulate the tissue with the light absorption characteristic to produce the thermal expansion, thus producing the shear wave. The frequency of shear wave induced by laser is higher and the frequency band is wider. By tracking the propagation of shear wave, Young’s modulus of tissue is reconstructed in the whole shear wave propagation region to further evaluate the elastic information of tissue. The feasibility of the method is verified by experiments. Compared with the experimental results of supersonic shear imaging (SSI), it is proved that the method can be used for quantitative elastic imaging of the phantoms. In addition, compared with the SSI method, this method can realize the noncontact excitation of the shear wave, and the frequency of the shear wave excited by the laser is higher than that of the acoustic radiation force (ARF), so the spatial resolution is higher. Compared to the traditional PA elastic imaging method, this method can obtain a larger imaging depth under the premise of ensuring the imaging resolution, and it has potential application value in the clinical diagnosis of diseases requiring noncontact quantitative elasticity.

建筑物轮廓线是各类应用的数据源，但散乱、不规则激光点云数据给轮廓线提取带来了难度。针对上述问题，提出一种基于多层级最小外包矩形规则建筑物轮廓线提取方法，首先使用迭代区域增长算法对轮廓点进行分组，根据点数最多的一组确定初始最小外包矩形。再对初始最小外包矩形进行多层级分解，使轮廓点与不同层级最小外包矩形重合，最后根据不同层级最小外包矩形生成轮廓线。使用Vaihingen城区中规则建筑物进行实验，实验结果表明：与最小面积方法与最大重叠度方法相比，所提方法能准确确定初始最小外包矩形，且提取效率得到略微提高。提取的轮廓线角点均方根误差为0.71 m，优于其他4种方法。所提方法可快速提取规则建筑物轮廓线，有利于后续三维重建。

针对基于旁瓣光束衍射反演的强激光远场焦斑测量无法提取旁瓣图像更外围最小可测信号的问题，笔者提出了基于邻域向量主成分分析（NVPCA）图像增强的旁瓣弱光信号区域波峰参数检测方法。采取的主要优化措施为：首先，将旁瓣图像中的每个像素和它的8邻域像素看作一个列向量，构建一个9维数据立方体，选择主成分分析变换后的第1维数据为NVPCA图像；其次，通过角度变换转化检测对象，检测所有方向上一维旁瓣曲线的各个波峰参数，获得旁瓣弱光信号区域能量的量化分布；然后，搜索每个旁瓣波峰在所有方向上的极大值位置点，连接对应位置点生成每个旁瓣波峰的极大值圆环，计算各极大值圆环的灰度均值；最后，选择大于局域对比度方法（LCM）目标分离阈值且最小的极大值圆环的灰度均值作为整个旁瓣光束的最小可测信号。实验结果表明，采用基于NVPCA图像增强的旁瓣弱光信号检测方法能够从旁瓣图像的第5波峰环分离和提取最小可测信号，动态范围比值提升至原来的1.528倍，各旁瓣波峰参数满足精度要求，为未来大型激光装置强激光远场的精确测量奠定了基础。

采用基于梯度和形状因子的网格优化方法适配能量分布并提升映射关系的可积性，在光源投影单位圆和目标面内分别进行等量初始四边形网格划分，使节点一一对应，并构建网格面积和映射关系可积性的权重评价函数。在保证所有节点位置拓扑关系不变的条件下，通过面积差场梯度和形状因子迭代调整网格分布，使映射关系满足能量分布要求同时优化可积性。基于网格优化的映射关系求解自由曲面并生成透镜，仿真所得非均匀光斑满足设计要求。该方法简化了平滑映射关系的求解过程，可以作为一种高效设计方法用于非均匀自由曲面透镜设计。

在基于光参量啁啾脉冲放大的拍瓦级超短超强飞秒激光装置中，光参量相位是阻碍脉冲时域压缩的关键因素。对中国工程物理研究院的数拍瓦全光参量啁啾脉冲放大装置（SILEX-II）的光参量相位演化进行了详细研究。研究结果表明，通过光参量放大过程累积的群延迟色散高达532 fs²，三阶色散高达5782 fs³，在未补偿光参量相位的情况下，压缩脉冲的时域峰值强度仅为傅里叶变换极限脉冲的43%。通过调节压缩器光栅间距，补偿了光参量相位的群延迟色散，将压缩脉冲的时域峰值强度增加至傅里叶变换极限脉冲的94%。研究结果为SILEX-II激光装置的脉冲时域压缩提供了有效指导，同时也为未来基于全光参量啁啾脉冲放大技术的10~100 PW高峰值功率激光器的设计提供了依据。

在光学俘获和操控单原子的实验中, 激光的低频强度噪声通常会加热原子, 从而缩短其存储时间并破坏其内态相干性。我们采用了一种基于电光振幅调制器(EOAM)的单级反馈环路来抑制激光低频噪声, 实现了0～1MHz的强度噪声的有效抑制, 100 kHz以下的噪声可降低20 dB, 500 kHz以下的噪声可降低10 dB。噪声抑制的频率范围涵盖了光学偶极阱的典型参量加热频率。将该装置用于单个铯原子实验将单个原子在偶极阱中的存储时间延长两个数量级, 测量的退相干时间也增加了5倍。

近年来，随着弹载电子设备集成度越来越高，内部热耗不断增加，如何实现设备的高效热管理，成为制约弹载电子设备进一步发展的重大难题。该文提出了一种应用于大功率弹载微波组合的相变储热模块，通过仿真分析手段研究了储热模块主体结构对储热模块整体储热性能的影响。综合考虑可制造性、质量、储热能力等多方面因素后，确认了储热模块的结构形式和最终选用的相变介质材料。利用增材制造技术加工出储热模块样品，并搭建热测试平台完成了该样品的散热效果评估。实验表明，在60 ℃环境下，模块总热耗为211 W，工作10 min后，模块表面最高温度为104.1 ℃，满足组合使用要求。该储热设计技术有效地解决了模块短时大功率下温升过高的问题，在弹载电子设备热管理领域有着广阔的应用前景。

Power-conversion-efficiencies (PCEs) of organic solar cells (OSCs) in laboratory, normally processed by spin-coating technology with toxic halogenated solvents, have reached over 19%. However, there is usually a marked PCE drop when the blade-coating and/or green-solvents toward large-scale printing are used instead, which hampers the practical development of OSCs. Here, a new series of N-alkyl-tailored small molecule acceptors named YR-SeNF with a same molecular main backbone are developed by combining selenium-fused central-core and naphthalene-fused end-group. Thanks to the N-alkyl engineering, NIR-absorbing YR-SeNF series show different crystallinity, packing patterns, and miscibility with polymeric donor. The studies exhibit that the molecular packing, crystallinity, and vertical distribution of active layer morphologies are well optimized by introducing newly designed guest acceptor associated with tailored N-alkyl chains, providing the improved charge transfer dynamics and stability for the PM6:L8-BO:YR-SeNF-based OSCs. As a result, a record-high PCE approaching 19% is achieved in the blade-coating OSCs fabricated from a green-solvent o-xylene with high-boiling point. Notably, ternary OSCs offer robust operating stability under maximum-power-point tracking and well-keep > 80% of the initial PCEs for even over 400 h. Our alkyl-tailored guest acceptor strategy provides a unique approach to develop green-solvent and blade-coating processed high-efficiency and operating stable OSCs, which paves a way for industrial development.

针对传统混合区域振幅自由度（MRAF）算法衍射效率低、非信号区域有散斑等问题，提出一种改进的MRAF算法。该算法引入球面相位作为初始相位，使用动态振幅限制，利用基于全域振幅限制的迭代方案确定最佳Z值，并使用爬山邻域算法对得到的相位进行分段式迭代优化，从而改善了非信号区域由于完全无振幅限制有散斑的问题。具体地，在全区域振幅限制阶段所提算法确保了目标光斑的匹配性并可以抑制散斑效应，而在混合区域振幅限制阶段则减小了误差。通过在三角形上进行数值仿真，对最终获得的结果进行光学实验仿真，结果表明，改进后的MRAF算法有97.77%高的衍射效率和0.09%低的均方根误差，并且峰值背景比（PBR）由0.0079提高至2.0357，相比基础的MRAF算法，对目标区域外围的散斑抑制效果更好，具有更高的应用价值。