We report tensorial tomographic Fourier ptychography (T²oFu), a nonscanning label-free tomographic microscopy method for simultaneous imaging of quantitative phase and anisotropic specimen information in 3D. Built upon Fourier ptychography, a quantitative phase imaging technique, T²oFu additionally highlights the vectorial nature of light. The imaging setup consists of a standard microscope equipped with an LED matrix, a polarization generator, and a polarization-sensitive camera. Permittivity tensors of anisotropic samples are computationally recovered from polarized intensity measurements across three dimensions. We demonstrate T²oFu’s efficiency through volumetric reconstructions of refractive index, birefringence, and orientation for various validation samples, as well as tissue samples from muscle fibers and diseased heart tissue. Our reconstructions of healthy muscle fibers reveal their 3D fine-filament structures with consistent orientations. Additionally, we demonstrate reconstructions of a heart tissue sample that carries important polarization information for detecting cardiac amyloidosis.

The article comments on a recent advance for wavelength tuning of laser particles, through a new photoelectrochemical etching method.

In this work, we developed a simple and direct circuit model with a dual two-diode model that can be solved by a SPICE numerical simulation to comprehensively describe the monolithic perovskite/crystalline silicon (PVS/c-Si) tandem solar cells. We are able to reveal the effects of different efficiency-loss mechanisms based on the illuminated current density-voltage (J-V), semi-log dark J-V, and local ideality factor (m-V) curves. The effects of the individual efficiency-loss mechanism on the tandem cell’s efficiency are discussed, including the exp(V/V_T) and exp(V/2V_T) recombination, the whole cell’s and subcell’s shunts, and the Ohmic-contact or Schottky-contact of the intermediate junction. We can also fit a practical J-V curve and find a specific group of parameters by the trial-and-error method. Although the fitted parameters are not a unique solution, they are valuable clues for identifying the efficiency loss with the aid of the cell’s structure and experimental processes. This method can also serve as an open platform for analyzing other tandem solar cells by substituting the corresponding circuit models. In summary, we developed a simple and effective methodology to diagnose the efficiency-loss source of a monolithic PVS/c-Si tandem cell, which is helpful to researchers who wish to adopt the proper approaches to improve their solar cells.

高性能的片上纳米激光器对通信、传感以及量子等领域的发展有着至关重要的意义。纳米激光器中高的光学限制因子可以保证更大的模式增益，实现更低的激光器阈值。首先阐明了借助物理气相沉积和原子层沉积制备Si₃N₄/WS₂/Al₂O₃三明治型纳米激光器阵列的工艺流程；构建了该纳米激光器的仿真模型，在仿真模型中对实际结构进行了简化并分析了Al₂O₃覆盖层厚度T、Si₃N₄微盘直径D和厚度H对光学限制因子的影响。光学限制因子随着Al₂O₃覆盖层T以及Si₃N₄微盘直径D的增加有先增加后减小的趋势，Si₃N₄微盘厚度H的减小也可以显著增加激光器的光学限制因子；最后展示了器件的荧光以及扫描电子显微镜的表征结果。该工作为集成光学芯片中可规模制备的高性能纳米激光器打下了良好基础。

稳定同位素测量技术已经在地球化学、地球物理、农业、生物、临床医学和生态科学等领域得到了众多应用。相对于传统的稳定同位素分析方法，基于激光吸收光谱技术的同位素分析技术，作为一种较新的同位素丰度测量方法，具有选择性好、精度高、体积小、无需样品预处理、可以实时原位同时测量气体浓度及同位素丰度等众多优点，得到了极大的关注和使用。本文主要以目前同位素测量的可调谐半导体激光吸收光谱技术、积分腔吸收光谱技术、腔衰荡吸收光谱技术三种激光吸收光谱方法为例，阐述了其基本原理、谱线选择、温压影响因素及其控制、系统组成结构以及部分应用测试结果。通过对测量系统的压力与温度的稳定控制的前提下，选取了合适的同位素测量谱线对，实现了大气CO₂气体的¹³C测量精度为0.3‰，煤层气CH₄气体的¹³CH₄测量精度为1.25‰，冰川水H₂O中¹⁸O、¹⁷O和²H的测量精度分别为0.3‰、0.2‰和0.5‰，以及呼吸气体中的¹³CO₂判识“金标准”。通过分析验证了激光吸收光谱技术在同位素测量方面的可行性和可靠性，也充分说明了基于激光吸收光谱技术的测量方法具有非常好的技术优势，将是光谱研究领域关注的重点内容，并在后续的科学研究中占据举足轻重的作用。

This paper investigates the combination of laser-induced breakdown spectroscopy (LIBS) and deep convolutional neural networks (CNNs) to classify copper concentrate samples using pretrained CNN models through transfer learning. Four pretrained CNN models were compared. The LIBS profiles were augmented into 2D matrices. Three transfer learning methods were tried. All the models got a high classification accuracy of >92%, with the highest at 96.2% for VGG16. These results suggested that the knowledge learned from machine vision by the CNN models can accelerate the training process and reduce the risk of overfitting. The results showed that deep CNN and transfer learning have great potential for the classification of copper concentrates by portable LIBS.

复杂空战背景下的抗红外诱饵干扰技术是红外空空导弹的核心技术之一。针对传统静态贝叶斯网络不能表达序列图像中特征变量在时序上动态变化关系，提出了一种符合人类视觉推理识别过程的时空关联推理网络抗干扰识别算法。首先，提出的时空关联推理网络在考虑特征空间约束关系的基础上，引入了特征变量时间约束的先验知识，建立表达特征时空关联的目标推理网络识别模型，从而增强了序列图像目标识别的稳定性；其次，通过仿真数据构建样本集，离线训练学习时空关联推理网络结构及特征跳转概率参数，确定概率推理网络识别离线模型；最后，依据测试数据，结合推理识别网络模型进行概率推理，实现对目标的识别分类。实验结果表明，在伴随红外诱饵干扰投放的条件下，基于时空关联推理网络的抗干扰识别率达到94%，比静态贝叶斯网络抗干扰识别算法高3%，有效提升了目标识别的稳定性。

目前现代测试技术发展较快, 为古代玉器的加工技术、 产源研究提供了无损研究手段。 利用红外光谱和能量色散X射线荧光光谱技术(EDXRF), 对浙江省遂昌县好川墓地中M52号墓出土的五件绿松石珠进行无损测试, 期望判断其可能的产地来源。 红外谱学特征显示, 3 468和3 514 cm^-1处可见红外吸收锐谱带, 是由于ν(OH)伸缩振动所致; 3 058 cm^-1附近可见ν(MFe, Cu—H₂O)伸缩振动, 1 014, 1 066和1 134 cm^-1处为ν₃(PO₄)伸缩振动。 与标准绿松石红外谱相比, 缺少1 637 cm^-1处峰, 此处为δ(H₂O)弯曲振动, 可能与样品在地下埋藏时间过久有关。 除天然绿松石吸收峰外, 在2 890和2 838 cm^-1处出现吸收峰, 分属亚甲基(—CH₂) 的不对称伸缩振动峰和对称振动峰, 在1 452 cm^-1附近也可以观察到其变形振动峰, 此外在1 552 cm^-1附近可见ν(C=C)伸缩振动。 这两处有机物吸收峰结合出土位置于红色漆痕处推断, 可能存在微量生漆残留。 两处基团峰与生漆漆酚的红外谱学特征基本相符, 存在样品埋藏时间过久, 漆器在土中腐朽后沾染到样品表面的可能性。 EDXRF数据中显示五件样品主量元素含量与理论值相比稍低, 硅含量稍高, 存在含硅杂质矿物, 微量元素中锌和钡的含量较高, Zn含量均在1 151~1 540 mg·kg^-1, Ba含量均在1 910~3 570 mg·kg^-1, 对比前人文献与湖北十堰及周边地区出产绿松石的元素数量级更为接近, 可作为判断五件绿松石珠玉料来源的一个证据。 通过显微照相对五件绿松石珠制作工艺进行观察, 可见五件样品均存在定向的抛磨痕迹, 且可见明显的一定数量的抛磨小面, 边缘可见线切割痕迹, 证明当时的好川文化先民已经具有加工打磨长宽不大于1 cm珠的能力; 加工珠形的方式是将不规则玉料原料分多个小面打磨直至成为桶珠形状, 而非直接进行弧面打磨; 钻孔周边可见明显平面, 孔形状较规整, 近圆形, 有抛磨痕迹, 说明好川墓地先民当时已具有钻孔工艺。 研究表明, 好川地区绿松石可能来自于湖北十堰及其周边地区的矿带, 浙西南地区自好川文化开始就使用较纯净的绿松石作为漆器镶嵌装饰, 埋藏过程中黏附漆类物质对绿松石表面造成一定污染, 镶嵌玉石漆器的制作工艺自良渚文化后有所传承, 且好川墓地先民已具备了一定程度的绿松石加工能力。 这对接下来进一步研究好川文化玉料来源问题奠定基础, 对考古学中好川及周边地区文化起源与交流探讨也有一定参考意义。