机器人辅助轮带磨削是一种基于计算机控制光学成形技术的确定性加工方法，具有成本低、柔性好、智能程度高且操作空间大的优点，因此机器人辅助轮带磨削作为一种较低成本的高精度、多自由度加工方法逐渐受到关注。文中介绍了所设计的机器人辅助轮带磨削系统结构及其加工原理，装置通过气动系统进行输出压力的柔顺控制。研究了任意加工姿态下机器人辅助轮带磨削中的恒力加载问题，分析了轮带磨削工具悬臂组件重力分量对其末端输出接触力的影响，建立了末端执行器的重力分量模型，并提出了基于姿态传感器的重力补偿控制方法，能够实现0~63 N范围内的恒力控制，并且最大压力波动小于1.82%，重力补偿系统的响应时间小于300 ms，实现了轮带磨削工具在任意姿态下的恒力加载。最后，根据Hertz接触理论和Preston方程完成了磨削工具在工件接触区域内的压强分布和速度分布分析，建立了轮带磨削工具的去除函数模型，并对碳化硅曲面与硫化锌非球面进行修形磨削实验，验证了装置加工的稳定性。

Nanophotonic waveguides hold great promise to achieve chip-scale gas sensors. However, their performance is limited by a short light path and small light–analyte overlap. To address this challenge, silicon-based, slow-light-enhanced gas-sensing techniques offer a promising approach. In this study, we experimentally investigated the slow light characteristics and gas-sensing performance of 1D and 2D photonic crystal waveguides (PCWs) in the near-IR (NIR) region. The proposed 2D PCW exhibited a high group index of up to 114, albeit with a high propagation loss. The limit of detection (LoD) for acetylene (C2H2) was 277 parts per million (ppm) for a 1 mm waveguide length and an averaging time of 0.4 s. The 1D PCW shows greater application potential compared to the 2D PCW waveguide, with an interaction factor reaching up to 288%, a comparably low propagation loss of 10 dB/cm, and an LoD of 706 ppm at 0.4 s. The measured group indices of the 2D and 1D waveguides are 104 and 16, respectively, which agree well with the simulation results.

Polarization is a basic characteristic of electromagnetic waves that conveys much optical information owing to its many states. The polarization state is manipulated and controlled for optical information security, optical encryption, and optical communication. Metasurface devices provide a new way to manipulate wave-fronts of light. A single ultrathin metasurface device can generate and modulate several differently polarized light fields, and thus carries optical information in several different channels. Terahertz (THz) waves have become widely used as carrier waves for wireless communication. Compact and functional metasurface devices are in high demand for THz elements and systems. This paper proposes a tri-layer metallic THz metasurface for multi-channel polarization generation and phase modulation with a high efficiency of approximately 80%. An azimuthally polarized THz vectorial beam generator is realized and characterized for use as a THz polarization analyzer. The incident polarization angle can be observed graphically with high accuracy. Moreover, a vectorial hologram with eight channels for different linear polarization states is demonstrated experimentally. The information in different holograms can be hidden by choosing the polarization channel for detection. This work contributes to achieving multi-functional metasurface in the THz band and can benefit THz communication and optical information security.

Ghost imaging (GI) is a technique to retrieve images by correlating intensity fluctuations. In this Letter, we present a novel scheme for GI referred to as second-order cumulants GI (SCGI). The image is retrieved from fluctuation information, and resolution may be enhanced compared to traditional GI. We experimentally performed SCGI image reconstruction, and the results are in agreement with theoretical predictions.