Yanqing Qiu

A machine vision-based weld seam positioning system for thermos cups is proposed. The system’s operational flow and image algorithms are designed to achieve automatic calibration of the weld seam orientation. Experimental results show a qualification rate of 97.8%, demonstrating robust performance across various cup models. The average positioning error is 45 pixels, with a maximum error of 153 pixels, corresponding to angular deviations of 0.68° and 2.30°, respectively. The average processing time of a single algorithm run is 128 ms, ensuring efficient operation in non-high-speed production scenarios. The results of this study have good application value and also provide some insights for the position calibration of other rotational objects.

This study introduces the design of a nonlinear frequency-modulated continuous wave (FMCW) laser ranging system. In contrast to the commonly used triangular wave linear modulation, this study utilizes sinusoidal wave modulation. The frequency information of the original sinusoidal frequency-modulated signal is extracted using an on-chip interferometer based on SiON waveguides and IQ demodulation technology. After fitting the measured interference signal at equal frequency intervals, the corresponding distance information is derived using the fast Fourier transform (FFT). The principles underlying this method are thoroughly analyzed and derived, with its accuracy confirmed through experimental validation.

Random speckle patterns contain valuable information about the incident light. Researchers have successfully constructed spectrometers and wavemeters by utilizing the speckles generated by inter-mode interferences of a multimode fiber (MMF). However, cameras were often employed to record the speckle data in previous reports. The camera's high cost (especially in the near-infrared range), large size, and low response speed limit the applications in optical communications, metrology, and optical sensing. A seven-core fiber (SCF) was fused with an MMF to capture the speckle pattern, where each core coupled part of the speckle field. Furthermore, we take advantage of the space division multiplexing capability of the SCF by incorporating an optical switch. This allows the variety of speckles generated by the incidence of different cores into the MMF. A convolutional neural network (CNN) regression algorithm was designed to analyze the complicated speckle data. The experimental results show that the proposed wavemeter can resolve adjacent wavelengths of 1 pm with an error of about 0.2 pm. We also discussed how different lengths of MMF influence the wavelength resolution. In conclusion, our research presents a robust and cost-effective approach to a wavelength measurement device by use of a seven-core optical fiber.

Airy beams are an intriguing type of non-diffraction wave packet that can exist in one-dimensional (1D) curved orbital plane systems. These beams have gained significant attention due to their unique properties, including non-diffraction, self-healing, and self-bending. In this study, we propose a method for generating high-efficiency and wideband Airy beams in microwave sections with reflective geometry, which is challenging to achieve due to the complexity of the Airy beam’s function and generation structure. Our approach involves both phase modulation and amplitude modulation. The designed metasurfaces were numerically simulated to obtain the most significant features of the microwave Airy beam. In addition, they are well in agreement with those predicted by theory.

In recent years, the concept of bound states in the continuum (BICs) in optics has become a research hotspot and has attracted the attention of many scholars. It provides an important physical mechanism for the generation of high-quality-factor optical resonance in high-refractive-index dielectric nanoparticles and all-dielectric metasurfaces. In this paper, two metasurfaces with the same structure of different materials are proposed. The resonant frequencies of the two structures are consistent, and the error is within 2.5 GHz. The quasi-BIC resonance is excited in the same way of breaking the symmetry. Subsequently, the electric field distribution, sensitivity, and figure of merit (FOM) of the two metasurfaces are analyzed, and sensitivities of 79.3 GHz/RIU and 72.4 GHz/RIU and the highest FOMs of 424.8 and 180.5, respectively, are achieved. These two all-dielectric metasurfaces are compared in this study, further confirming the advantages of all-silicon metasurfaces.

In this study, a perfect metamaterial absorber (PMMA) based on an indium antimonide temperature-sensitive material is designed and investigated in the terahertz region. We demonstrate that it is an ideal perfect narrow-band absorber with polarization-insensitive and wide-angle absorption properties. Numerical simulation results show that the proposed PMMA can be operated as a temperature sensor with a sensitivity of 21.9 GHz/K. A graphene layer was added to the PMMA structure to improve the sensitivity, and the temperature sensitivity was increased to 24.4 GHz/K. Owing to its excellent performance, the proposed PMMA can be applied in thermal sensing, detection, and switching.