To ensure the frequency accuracy of a heterodyne laser source in the ambient temperature range of -20°C to 40°C, a dual-longitudinal-mode thermally stabilized He–Ne laser based on non-equilibrium power locking was designed. The ambient adaptive preheating temperature setting scheme ensured the laser could operate normally in the range of -20°C to 40°C. The non-equilibrium power-locked frequency stabilization scheme compensated for the frequency drift caused by different stabilization temperatures. The experimental results indicated that the frequency accuracy of the laser designed in this study could reach 5.2 × 10^-9 in the range of -20°C to 40°C.

The performance and reliability of ferroelectric thin films at temperatures around a few Kelvin are critical for their application in cryo-electronics. In this work, TiN/Hf_0.5Zr_0.5O₂/TiN capacitors that are free from the wake-up effect are investigated systematically from room temperature (300 K) to cryogenic temperature (30 K). We observe a consistent decrease in permittivity (ε_r) and a progressive increase in coercive electric field (E_c) as temperatures decrease. Our investigation reveals exceptional stability in the double remnant polarization (2P_r) of our ferroelectric thin films across a wide temperature range. Specifically, at 30 K, a 2P_r of 36 μC/cm² under an applied electric field of 3.0 MV/cm is achieved. Moreover, we observed a reduced fatigue effect at 30 K in comparison to 300 K. The stable ferroelectric properties and endurance characteristics demonstrate the feasibility of utilizing HfO₂ based ferroelectric thin films for cryo-electronics applications.

为了提高柔性机器人抓握传感中掌心表面的重构精度，本文基于COMSOL仿真，在436 mm×436 mm×2 mm聚丙烯板上，采用7只经聚二甲基硅氧烷（PDMS）封装的光纤光栅（FBG）柔性传感器，选取环形布设的方式，在板末端中心与两角分别受力的情况下，使用光纤光栅解调仪采集实验中的传感器数据，并通过三次样条插值法进行连续化。设定数个平面Y与拟合圆环相交，计算过点函数获得三维曲面点集，实现了空间曲面的拟合可视化显示。在曲面末端中心受力时，板末端位移最小相对误差为0.549%，最大相对误差为8.300%，最小绝对误差为0.051 cm，最大绝对误差为1.255 cm，板末端两角受力时，板面重构末端位移最小相对误差为2.546％，最大相对误差为14.289％，最小绝对误差为0.005 cm，最大绝对误差为0.729 cm。实验结果为柔性机器人掌心抓握传感提供了应用基础。

Controlling the dispersion characteristic of metasurfaces (or metalenses) along a broad bandwidth is of great importance to develop high-performance broadband metadevices. Different from traditional lenses that rely on the material refractive index along the light trajectory, metasurfaces or metalenses provide a new regime of dispersion control via a sub-wavelength metastructure, which is known as negative chromatic dispersion. However, broadband metalenses design with high-performance focusing especially with a reduced device dimension is a significant challenge in society. Here, we design, fabricate, and demonstrate a broadband high-performance diffractive-type plasmonic metalens based on a circular split-ring resonator metasurface with a relative working bandwidth of 28.6%. The metalens thickness is only 0.09λ0 (λ0 is at the central wavelength), which is much thinner than previous broadband all-dielectric metalenses. The full-wave simulation results show that both high transmissive efficiency above 80% (the maximum is even above 90%) and high average focusing efficiency above 45% (the maximum is 56%) are achieved within the entire working bandwidth of 9–12 GHz. Moreover, an average high numerical aperture of 0.7 (NA=0.7) of high-efficiency microwave metalens is obtained in the simulations. The broadband high-performance metalens is also fabricated and experimental measurements verify its much higher average focusing efficiency of 55% (the maximum is above 65% within the broad bandwidth) and a moderate high NA of 0.6. The proposed plasmonic metalens can facilitate the development of wavelength-dependent broadband diffractive devices and is also meaningful to further studies on arbitrary dispersion control in diffractive optics based on plasmonic metasurfaces.

太阳望远镜内部因太阳辐射作用使镜面升温，镜面上方产生局部大气湍流，导致镜面视宁度不佳，从而造成像质的严重衰减。文中基于温度梯度和气体流动导致固体-流场的耦合作用，提出镜面视宁度效应的形成机制，建立湍流大气光学产生镜面视宁度效应的理论，利用1 550 mm大口径双曲面镜的实验数据推导并验证镜面视宁度的实验模型，并对太阳望远镜主镜温控目标进行确定。在自然对流和强迫对流两种条件下，不同环境风速时镜面温差改变对镜面视宁度的影响。结果表明：镜面温差和环境风速与镜面视宁度相关性很强，增加主动通风可以降低镜面视宁度。温差是4 ℃条件下，自然对流时镜面视宁度为 1.43″；温差是 3 ℃条件下，0.2 m/s 强迫对流时镜面视宁度为 0.44″，1 m/s 强迫对流时镜面视宁度为 0.27″。根据镜面视宁度效应容差标准，在0.2 m/s强迫对流条件下，镜面-空气温差应控制在0.2 K以下；在1.0 m/s强迫对流条件下，镜面-空气温差应控制在1 K以下。此研究成果旨在揭示空气湍流的形成机理与传播规律及其对望远镜像质退化影响规律，为提升大口径太阳望远镜工作分辨率奠定基础。

We propose an absolute distance measurement method that employs heterodyne and superheterodyne combined interferometers to achieve synchronous detection and demodulation of multiwavelengths. Coarse and fine synthetic wavelengths are generated by a dual-longitudinal-mode He–Ne laser and four acoustic optical frequency shifters. Further, to improve phase synchronization measurement for multiwavelengths, we analyze the demodulation characteristics of coarse and fine measurement signals and adopt a demodulation method suitable for both signals. Experimental results demonstrate that the proposed method can achieve high-precision synchronous demodulation of multiwavelengths, and standard deviation is 1.7 × 10^-5 m in a range of 2 m.