Author Affiliations
Abstract
1 Aerospace Laser Technology and Systems Department, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
3 Shanghai Typhoon Institute, China Meteorological Administration, Shanghai 200030, China
A method of spectrum estimation based on the genetic simulated annealing (GSA) algorithm is proposed, which is applied to retrieve the three-dimensional wind field of typhoon Nangka observed by our research group. Compared to the genetic algorithm (GA), the GSA algorithm not only extends the detection range and guarantees the accuracy of retrieval results but also demonstrates a faster retrieval speed. Experimental results indicate that both the GA and GSA algorithms can enhance the detection range by 35% more than the least squares method. However, the convergence speed of the GSA algorithm is 17 times faster than that of the GA, which is more beneficial for real-time data processing.
coherent Doppler lidar three-dimensional wind field retrieval genetic simulated annealing algorithm spectrum estimation typhoon Chinese Optics Letters
2024, 22(4): 040101
1 武汉科技大学 信息科学与工程学院，湖北 武汉 430080
2 武汉科技大学 冶金自动化与检测技术教育部工程研究中心，湖北 武汉 430080
针对传统SIFT匹配算法复杂、特征冗余点多、难以满足实时性等问题，本文提出了一种具有局部自适应阈值的SIFT快速图像匹配算法。首先，所提方法在SIFT算法的基础上，对构建的高斯金字塔进行了优化，通过减少金字塔层数来消除冗余特征点以提高检测效率，并根据图像局部对比度来自适应提取FAST算法中的阈值从而实现高质量的特征点检测，筛选出鲁棒性较强的特征点进行更准确的匹配；其次，采用高斯圆形窗口建立32维降维特征向量，提高算法运行效率；最后，根据匹配特征点对之间的几何一致性对特征点进行提纯，有效减少误匹配。实验结果表明，本文方法在匹配精度和运算效率方面的综合表现均优于SIFT算法及其他对比匹配算法，相比传统的SIFT算法，匹配精度提高了约10%，算法运行时间缩短了约49%。在图像发生尺度、旋转以及光照变化的情况下，正确匹配率在93%以上。
SIFT算法 高斯金字塔 自适应阈值 特征描述符 图像匹配 SIFT algorithm Gaussian pyramid adaptive thresholds feature descriptor image matching 强激光与粒子束
2024, 36(4): 043002
Author Affiliations
Abstract
1 College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China
2 School of Information and Communications, National University of Defense Technology, Wuhan 430035, China
3 Nanhu Laser Laboratory, National University of Defense Technology, Changsha 410073, China
4 Hunan Provincial Key Laboratory of High Energy Laser Technology, National University of Defense Technology, Changsha 410073, China
High-power ultrafast laser amplification based on a non-polarization maintaining fiber chirped pulse amplifier is demonstrated. The active polarization control technology based on the root-mean-square propagation (RMS-prop) algorithm is employed to guarantee a linearly polarized output from the system. A maximum output power of 402.3 W at a repetition rate of 80 MHz is realized with a polarization extinction ratio (PER) of > 11.4 dB. In addition, the reliable operation of the system is verified by examining the stability and noise properties of the amplified laser. The M2 factor of the laser beam at the highest output power is measured to be less than 1.15, indicating a diffraction-limited beam quality. Finally, the amplified laser pulse is temporally compressed to 755 fs with a highest average power of 273.8 W. This is the first time, to the best of our knowledge, that the active polarization control technology was introduced into the high-power ultrafast fiber amplifier.
active polarization control root-mean-square propagation algorithm linearly polarized laser chirped pulse amplification femtosecond laser fiber laser Chinese Optics Letters
2024, 22(4): 041403
1 南京理工大学理学院，江苏 南京 210094
2 中国商飞上海飞机制造有限公司，上海 201324
通过测量板状材料中Lamb波的频散曲线可以反演出材料的特性参数，因而这种方法在材料表征、评价和无损检测等领域具有广阔的应用前景。基于移动激光源法测量了薄板中Lamb波的频散曲线，通过高速转镜使聚焦的激光线源在样品表面以与相应Lamb波模式匹配的速度移动，当激光移动速度与Lamb波相速度一致时，可以以较高的效率激发出此Lamb波模式。通过改变转镜的转速，即改变激光线源的移动速度，记录不同移动速度下所激发的Lamb波频谱，可以得到Lamb波的频散曲线。在此基础上，结合粒子群优化算法反演了铝板以及聚苯乙烯板中的纵波波速与横波波速。在仿真中，开展了不同模式和频厚积处频散特性对材料参数的敏感度分析，并比较了不同噪声水平下以及不同模态频散数据选取所对应的拟合效果，讨论了2500~4000 m/s相速度区间基于频散曲线的反演敏感度问题。最终基于移动激光源实验中所提取的铝板中Lamb波的频散数据进行参数反演，结果显示，纵波声速和横波声速的反演误差均小于1.5%，证明了该方案的有效性。
测量 激光超声 参数反演 移动连续激光源 粒子群优化算法
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 School of Physics, Dalian University of Technology, Dalian 116024, China
2 School of Computer and Electronic Information / School of Artificial Intelligence, Nanjing Normal University, Nanjing 210023, China
3 School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian 116024, China
In this paper, a cost-effective and miniaturized instrument is proposed, which is based on a tunable modulated grating Y-branch (MG-Y) laser for rapid temperature measurement using a Fabry-Perot interferometer (FPI) sensor. The FPI sensor with a 1 463-μm cavity length is a short segment of a capillary tube sandwiched by two sections of single-mode fibers (SMFs). This system has a broad tunable range (1 527 nm–1 567 nm) with a wavelength interval of 8 pm and a tuning rate of 100 Hz. Temperature sensing experiments are carried out to investigate the performance of the system by demodulating the absolute cavity length of the FPI sensor using a cross-correlation algorithm. Experimental results show that the sensor can reach the response time as short as 94 ms with the sensitivity of 802 pm/℃. Benefiting from the homemade and integrated essential electrical circuits, the entire system has the small size, low cost, and practical application potential to be used in the harsh environment for rapid temperature measurement.
MG-Y laser interrogator rapid temperature measurement cross-correlation algorithm Photonic Sensors
2024, 14(1): 240125
上海大学通信与信息工程学院，特种光纤与光接入网省部共建国家重点实验室培育基地，特种光纤与先进通信国际合作联合实验室，上海 200444
传统的光学透镜存在体积较大、聚焦效率低、焦点半峰全宽较大以及在高数值孔径的透镜中性能表现不佳等问题。而光学超表面凭借其自身的亚波长结构，具有强大的操控光相位的能力。相比于传统透镜，超透镜具有尺寸小、厚度薄以及聚焦性能好等优点。本文提出一种基于目标优先算法的逆向设计方法，设计了一种基于低折射率聚合物材料的超透镜结构。其在传播方向上的厚度仅为3.2 μm，在1550 nm的工作波长下，数值孔径为0.82，聚焦效率为72%。较传统设计方法而言，该方法具有计算复杂度低和设计效率高等优点。设计的器件可采用高精度微纳打印技术实现批量化的快速制造。考虑到超透镜在制备过程中存在制造容差，进一步讨论了超透镜轮廓偏移以及三维旋转操作对所设计的二维超透镜的影响。
超表面 超透镜 逆向设计 目标优先算法 偏振不依赖性
