The compact, sensitive, and multidimensional displacement measurement device plays a crucial role in semiconductor manufacture and high-resolution optical imaging. The metasurface offers a promising solution to develop high-precision displacement metrology. In this work, we proposed and experimentally demonstrated a two-dimensional displacement (XZ) measurement device by a dielectric metasurface. Both transversal and longitudinal displacements of the metasurface can be obtained by the analysis of the interference optical intensity that is generated by the deflected light beams while the metasurface is under linearly polarized incidence. We experimentally demonstrated that displacements down to 5.4 nm along the x-axis and 0.12 µm along the z-axis can be resolved with a 900 µm × 900 µm metasurface. Our work opens up new possibilities to develop a compact high-precision multidimensional displacement sensor.

由于仪器传递函数（Instrument Transfer Function, ITF）能准确反映仪器在空间频率上的响应特征，被广泛应用于仪器规范之中。目前多采用刻有单一台阶特征或不同周期正弦特征的平面测试板对干涉仪的ITF进行检测。针对平面测试板无法完成高陡度球面/非球面镜检测时ITF标定的问题，提出了根据球面台阶测试板标定高陡度镜面检测的子孔径拼接ITF的方法。通过超精密车削技术制作了球面台阶测试板，并对其进行拼接检测，根据梯度定位法和旋转矩阵完成检测孔径中台阶的定位及采样，利用傅里叶变换方法实现对台阶实测面形的功率谱密度求解，最后与理想面形功率谱密度做比获得ITF。对口径100 mm、曲率半径100 mm、带有同心圆环台阶结构的球面台阶测试板进行拼接检测以及数据分析，实验结果表明：在1 mm⁻¹的空间频率范围内，各个子孔径对高陡度镜面的检测水平平均可达到82.72%，具有较好的检测精度，随后ITF逐渐衰减，当空间频率在1.5 mm⁻¹左右时，仅能达到40%~60%。

贵金属纳米颗粒由于具有独特的物理特性而被广泛应用于催化，光热治疗及表面增强光谱等领域，然而银纳米颗粒的化学稳定性差，金纳米颗粒的催化性能依赖其大小，这严重限制了其进一步应用。本文通过一种简单温和的湿化学方法合成了具有较好单分散性的球形金银合金纳米颗粒。根据表征结果可知，合金颗粒的形貌尺寸均一，金和银两种金属元素分布均匀，属于一种多晶的晶体结构。研究结果表明，通过改变金和银的摩尔比，能够很容易实现金银合金纳米颗粒表面等离激元共振峰的调控。此外，由于金和银两种元素的协同效应，金银合金纳米颗粒同时具有较好的稳定性和较强的催化性能，且要远好于单组分的金纳米颗粒和银纳米颗粒。该研究为构建多种较高性能的合金纳米材料提供了新思路，为减少环境中芳香族硝基有机污染物提供了可能途径。

A practical experimental method is proposed to investigate thermal transport by characterizing the motion of plasma flows through a x-ray spectroscopic technique using tracers. By simultaneously measuring multiple parameters, namely, the mass-ablation rate, the temporal evolution of plasma flow velocities and trajectories and the temperature, it is possible to observe a variety of physical processes, such as shock wave compression, heating by thermal waves, and plasma thermal expansion, and to determine their relative importance in different phases during the irradiation of CH and Au targets. From a comparison with hydrodynamic simulations, we find significant differences in the motion of the plasma flows between CH and Au, which can be attributed to different sensitivities to the thermal transport process. There are also differences in the ablation and electron temperature histories of the two materials. These results confirm that velocities and trajectories of plasma motion can provide useful evidence in the investigation of thermal conduction, and the approach presented here deserves more attention in the context of inertial confinement fusion and high-energy-density physics.

Phase carried by two orthogonal polarizations can be manipulated independently by controlling both the geometric size and orientation of the dielectric nanopost. With this characteristic, we demonstrate a novel multifunctional metasurface, which converts part of the incident linearly polarized light into its cross-polarization and encodes the phase of the two orthogonal polarizations independently. A beam splitter and a bifocal metalens were realized in a single-layer dielectric metasurface by this approach. We fabricated the bifocal metalens and demonstrated that two focal spots in orthogonal polarizations can be separated transversely or longitudinally at will. The proposed approach shows a new route to design multifunctional metasurfaces with various applications in holography and three-dimensional display.

A multifunctional photo-thermal therapeutic nano-platform Y2O3:Nd3+/Yb3+/Er3+@SiO2@Cu2S (YR-Si-Cu2S) was designed through a core–shell structure, expressing the function of bio-tissue imaging, real-time temperature detection, and photo-thermal therapy under 808 nm light excitation. In this system, the core Y2O3:Nd3+/Yb3+/Er3+ (YR) takes the responsibility of emitting optical information and monitoring temperature, while the shell Cu2S nano-particles carry most of the photo-thermal conversion function. The temperature sensing characteristic was achieved by the fluorescence intensity ratio using the thermally coupled energy levels (TCLs) S3/24/H211/2 of Er3+, and its higher accuracy for real-time temperature measurement in the bio-tissue than that of an infrared thermal camera was also proved by sub-tissue experiments. Furthermore, the photo-thermal effect of the present nano-system Y2O3:Nd3+/Yb3+/Er3+@SiO2@Cu2S was confirmed by Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) ablation. Results indicate that YR-Si-Cu2S has application prospect in temperature-controlled photo-thermal treatment and imaging in bio-tissues.