1 新疆大学 机械工程学院, 新疆 乌鲁木齐 830046
2 西安交通大学 机械工程学院 机械制造系统工程国家重点实验室, 陕西 西安 710049
3 新拓三维技术（西安）有限公司 创新实验室, 陕西 西安 710086
小尺寸零件的表面积小、结构复杂，传统标志点拼接方法需要在零件表面人工粘贴标志点，导致表面的测量数据缺失出现孔洞。基于特征的点云拼接方法要求零件表面具有易区分的几何或距离特征，不适用于包含重复性特征的回转体零件。本文提出一种基于机械拼接的无标志点扫描测量方法，不需要粘贴标志点，不依赖于零件表面特征。首先，采用基于摄影测量的相机标定方法得到相机的高精度内外参数，重建标定板上靶点的高精度三维坐标，接着通过跟踪编码靶点的位置建立转台不同转角对应的旋转矩阵，进而解算出转轴方向向量和轴上定点坐标，实现转轴和相机的同步标定。在完成两个转轴位姿精确标定的基础上，利用转台转角构建旋转拼接矩阵，实现多视角点云粗配准。最后，基于法向迭代最近点算法(Normal Iterative Closest Point, NICP)完成点云的精配准。实验结果表明：使用靶点跟踪法标定后的两转轴夹角误差较传统的标准球拟合法低0.023°，标定后测量标准球的整体平均尺寸误差小于0.012 mm；在小尺寸零件自动化测量时，机械拼接方法在精配准后的点云拼接效果与标志点拼接方法相近，且拼接稳定性更高。机械拼接方法适用于无法粘贴标记点的小尺寸零件三维形貌测量场景。
结构光 机械拼接 小尺寸零件 转轴标定 NICP算法 structured light mechanical splicing small-size parts axis calibration NICP algorithm 
Author Affiliations
Abstract
1 Laboratory of Infrared Materials and Devices, Research Institute of Advanced Technologies, Ningbo University, Ningbo 315211, China
2 Zhejiang Key Laboratory of Photoelectric Materials and Devices, Ningbo University, Ningbo 315211, China
3 Ningbo Institute of Oceanography, Ningbo 315832, China
4 Department of Quantum Science and Technology, Research School of Physics, Australian National University, Canberra, ACT 2601, Australia
The design of nonlinear photonic Vogel’s spiral based on quasi-crystal theory was demonstrated. Two main parameters of Vogel’s spiral were arranged to obtain multi-reciprocal circles. Typical structure was fabricated by the near-infrared femtosecond laser poling technique, forming a nonlinear photonic structure, and multiple ring-like nonlinear Raman–Nath second-harmonic generation processes were realized and analyzed in detail. The structure for the cascaded third-harmonic generation process was predicted. The results could help deepen the understanding of Vogel’s spiral and quasi-crystal and pave the way for the combination of quasi-crystal theory with more aperiodic structures.
nonlinear photonic quasi-crystal second-harmonic generation Vogel’s spiral nonlinear Raman–Nath diffraction femtosecond laser poling Chinese Optics Letters
2024, 22(3): 031902
1 南京工业大学 机械与动力工程学院，南京 211816
2 南京工业大学 电气工程与控制科学学院，南京 211816
过度使用抗生素导致的水污染，对自然环境和人类健康造成了重大威胁。低温等离子体作为一种绿色环保的高级氧化技术，被认为是一种最具前景的抗生素降解方法之一，然而在降解效率和能量效率方面还有待进一步提高。利用纳秒脉冲放电激励针-水结构气液放电，获得了一种能产生高活性等离子体的瞬态火花模式放电，并应用于水中四环素降解，研究了脉冲电压、频率、初始浓度、初始pH值等参数对四环素降解的影响，结果表明初始浓度50 mg/L，脉冲电压9 kV、频率2 kHz，初始pH值为中性的条件下四环素的降解率最高，处理时间10 min时降解率达到了91.6%，能量效率和每阶电能分别为0.165 g·kW−1·h−1和0.78 kW·h·m−3。自由基淬灭实验表明羟基自由基 (·OH) 在四环素降解过程中起主要作用，而H2O2和O3的作用稍弱。细胞毒性实验也表明气液放电处理10 min后的溶液毒性显著下降。
低温等离子体 气液放电 四环素抗生素 抗生素降解 活性氧物种 non-thermal plasma gas-liquid discharge tetracycline antibiotics antibiotic degradation reactive oxygen species 强激光与粒子束
2024, 36(3): 035001
Author Affiliations
Abstract
1 College of Information Science Technology, Dalian Maritime University, Dalian 116026, China
2 China Academy of Space Technology, Beijing 100086, China
3 State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710119, China
4 University of Chinese Academy of Sciences, Beijing 100049, China
5 e-mail: panan@opt.cn
Combining the synthetic aperture radar (SAR) with the optical phase recovery, Fourier ptychography (FP) can be a promising technique for high-resolution optical remote imaging. However, there are still two issues that need to be addressed. First, the multi-angle coherent model of FP would be destroyed by the diffuse object; whether it can improve the resolution or just suppress the speckle is unclear. Second, the imaging distance is in meter scale and the diameter of field of view (FOV) is around centimeter scale, which greatly limits the application. In this paper, the reasons for the limitation of distance and FOV are analyzed, which mainly lie in the illumination scheme. We report a spherical wave illumination scheme and its algorithm to obtain larger FOV and longer distance. A noise suppression algorithm is reported to improve the reconstruction quality. The theoretical interpretation of our system under random phase is given. It is confirmed that FP can improve the resolution to the theoretical limit of the virtual synthetic aperture rather than simply suppressing the speckle. A 10 m standoff distance experiment with a six-fold synthetic aperture up to 31 mm over an object of size is demonstrated.
Photonics Research
2023, 11(12): 2072
光学 精密工程
2023, 31(16): 2430
针对红外图像颜色、纹理等信息不够丰富，导致检测精度相较于可见光图像低；夜间红外行人目标检测模型参数量大、依赖高性能GPU资源，导致检测速度慢等问题，提出一种融合行人目标精细尺度嵌入的多检测层、轻量化实时检测模型。首先为了获取更精确的红外行人位置特征，在原始Yolov4-tiny结构上设计了64×64精细尺度检测层并增加残差结构加深主干网络，以融合红外行人的位置特征；其次针对红外行人目标宽高比相对固定的特点，应用K-means++聚类分析出适用于红外行人检测的先验框预置参数；最后为了减少模型参数，通过通批量归一化层道剪枝实现模型轻量化，同时利用知识蒸馏算法完成TIPRD的微量调控。实验结果表明，轻量化红外行人实时检测模型检测速度达到了88.7 帧/s，平均检测精度达到89.2%，模型大小为4 MB，相较于Yolov4-tiny平均检测精度提升了8.6%，模型大小缩小了19.5 MB，相较于Yolov4缩小了264 MB。在Jetson Nano移动开发平台部署该模型验证了实际工程应用的有效性，对开发汽车辅助驾驶系统以降低夜间交通事故发生率具有重要意义。
红外检测 深度学习 多检测层 模型剪枝 知识蒸馏 Infrared detection Deep learning Multiple detection layers Model pruning Knowledge distillation
Author Affiliations
Abstract
MOE Key Laboratory of Optoelectronic Science and Technology for Medicine and Fujian Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou, Fujian 350007, P. R. China
Early diagnosis of liver cancer plays a significant role in reducing its high mortality. In this preliminary study, the feasibility of using serum surface-enhanced Raman spectroscopy (SERS) to identify liver cancer was studied. Serum samples were obtained from liver cancer patients and healthy controls. The differences between the SERS spectra of pre-operation and post-operation of liver cancer patients were also analyzed. The general shape and trend of SERS spectra of health control and liver cancer patients were similar. Multivariate analysis, e.g., PLS-SVM, might be useful for the discrimination of serum SERS spectra of pre-operation and post-operation.Early diagnosis of liver cancer plays a significant role in reducing its high mortality. In this preliminary study, the feasibility of using serum surface-enhanced Raman spectroscopy (SERS) to identify liver cancer was studied. Serum samples were obtained from liver cancer patients and healthy controls. The differences between the SERS spectra of pre-operation and post-operation of liver cancer patients were also analyzed. The general shape and trend of SERS spectra of health control and liver cancer patients were similar. Multivariate analysis, e.g., PLS-SVM, might be useful for the discrimination of serum SERS spectra of pre-operation and post-operation.
Surface-enhanced Raman spectroscopy (SERS) serum liver cancer multivariate analysis Journal of Innovative Optical Health Sciences
2022, 15(5): 2250032
光学 精密工程
2022, 30(13): 1591
1 兰州交通大学国家绿色镀膜技术与装备工程技术研究中心, 甘肃 兰州 730070
2 兰州交通大学光电技术与智能控制教育部重点实验室, 甘肃 兰州 730070
提出一种基于CCD相机和双朗伯靶的能流均匀性测量系统和方法。系统有两块朗伯靶,其中一块是固定的水冷朗伯靶,靶中心开孔处装有一个用来获得区域灰度值的热流探测器,另一块是可移动朗伯靶,用于拍摄没有探测器的光斑图像。所提方法可以直接获得探测器区域的像素灰度值,使得测量过程简单精确。详细阐述了测量原理和聚焦光斑灰度图像能流密度分布提取的整个过程,并搭建了平台,测量了多块小型定日镜的光斑能流分布,验证了所提方法的正确性和可行性。通过重复性实验和误差分析,结果表明,所提方法检测的峰值能流密度误差小于2.4%,所提方法可用于线性菲涅耳聚光系统二次聚光器开口平面处吸热管表面的能流分布检测。
非线性光学 能流密度 光热耦合性 CCD相机 像素灰度值 光斑灰度图像 激光与光电子学进展
2020, 57(19): 191903
