Author Affiliations
Abstract
1 Institute of Quantum Electronics, School of Electronics, Peking University, Beijing 100871, China
2 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
To obtain cold atom samples with temperatures lower than 100 pK in the cold atom physics rack experiment of the Chinese Space Station, we propose to use the momentum filtering method for deep cooling of atoms. This paper introduces the experimental results of the momentum filtering method verified by our ground testing system. In the experiment, we designed a specific experimental sequence of standing-wave light pulses to control the temperature, atomic number, and size of the atomic cloud. The results show that the momentum filter can effectively and conveniently reduce the temperature of the atomic cloud and the energy of Bose–Einstein condensation, and can be flexibly combined with other cooling methods to enhance the cooling effect. This work provides a method for the atomic cooling scheme of the ultra-cold atomic system on the ground and on the space station, and shows a way of deep cooling atoms.
momentum filter standing-wave pulse Bose–Einstein condensation optical dipole trap two-stage cooling space station Chinese Optics Letters
2023, 21(8): 080201
1 湖北工业大学电气与电子工程学院，湖北 武汉 430064
2 新能源及电网装备安全监测湖北省工程研究中心，湖北 武汉 430064
针对输电线路绝缘子缺陷检测准确率低和检测速度慢的问题，提出了一种基于多尺度特征编码和双重注意力融合的输电线路绝缘子缺陷检测方法。首先，为了使检测模型适应缺陷绝缘子特征尺度的多样性，编码网络采用Res2Net50提取更细粒度的特征，并在之后嵌入空洞空间金字塔池化模块实现多个尺度捕捉绝缘子及其缺陷的特征；其次，为了减少解码网络中特征信息的缺失，将主干网络的不同层特征与efficient channel attention注意力模块串联，并分别与经过squeeze and excitation注意力模块的各反卷积特征相加形成双重注意力融合。实验结果表明，所提方法的均值平均精度值约为95.35%，每秒传输帧数约为65.95，与其他方法相比，该方法对无人机绝缘子缺陷的准确检测具有一定的参考价值。
图像处理 绝缘子缺陷检测 空洞空间金字塔池化 多尺度特征编码 双重注意力融合 激光与光电子学进展
2022, 59(24): 2410008
1 湖北工业大学电气与电子工程学院，湖北 武汉 430068
2 美国南卡罗来纳大学计算机科学与工程系，南卡罗来纳州哥伦比亚 29201
针对当前跨模态行人重识别算法大多聚类能力不强、且难以提取高效辨别性特征的问题，提出了一种多粒度跨模态行人重识别算法。首先，在骨干网络Resnet50中加入非局部注意力机制模块，关注长距离像素之间的关系，保留细节信息；其次，采用多分支网络提取不同细粒度特征信息，增强模型的辨别性特征提取能力；最后，联合基于样本的三元组损失和基于中心的三元组损失监督训练，加速模型收敛。所提算法在SYSU-MM01数据集的全搜索模式下Rank-1和mean average precision分别达到62.83%和58.10%，在RegDB数据集的可见光到红外模式下Rank-1和mAP分别达到87.78%和76.22%。
光计算 跨模态 行人重识别 注意力机制 多粒度 三元组损失 激光与光电子学进展
2022, 59(22): 2220001
1 湖北工业大学 电气与电子工程学院，武汉 430068
2 湖北工业大学 太阳能高效利用湖北省协同创新中心，武汉 430068
3 美国南卡罗来纳大学 计算机科学与工程系，南卡 哥伦比亚 29201
针对遥感图像道路提取信息丢失问题，提出了一种基于残差神经网络的道路提取算法。首先构建编码器?解码器网络，结合预编码器以及空洞卷积模块进行训练，提取更多的语义信息；其次并联设计的空洞卷积模块加在编码器?解码器结构的中间部分，它可以对不同感受野的特征图进行特征提取；最后编码器?解码器之间采用跳连的方式进行多尺度的特征融合，学习更多低维和高维的特征。实验结果表明，在Massachusetts道路数据集上，该方法相比其他算法在Precision、Recall和F1?score性能指标上分别有11 %、0.3 %和7.4 %的提升；同时在Accuracy指标上也达到了97.9 %，相比于其他算法，该算法有一定的应用价值。
道路提取 遥感图像 空洞卷积 多尺度特征融合 road extraction remote sensing image dilated convolution multi-scale feature fusion 
Author Affiliations
Abstract
Institute of Quantum Electronics, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China
We propose, design, and realize a compact stabilized laser system that can be tuned within 24 GHz automatically. This laser system consists of two distributed feedback (DFB) lasers, one of which is reference and locked to the D2 line of Rb87, the other laser is a slave that is locked to the reference laser via a loop servo. We measured the frequency of the beating signal of the two lasers and generated an error signal, which controlled the frequency of the slave laser to close the loop. We compressed the fluctuation of the beating signal’s frequency to less than 1 MHz. Furthermore, the system can also automatically determine and control whether the slave is red detuned or blue detuned to the reference. The dimensions of our laser system are about 15 cm × 20 cm × 10 cm. This kind of laser system can be applied in many important applications, such as atomic interferometer and cold atomic clock.
140.2020 Diode lasers 140.3425 Laser stabilization Chinese Optics Letters
2018, 16(3): 031403
设计并实现了一种低功耗、小型化、可长期稳定运行的自动稳频激光系统。通过设计并实现高效率、低纹波的电压源，较大幅度地降低了整个系统的功耗和体积；通过设计并实现高性能温度控制电路、电流控制电路和稳频电路，得到了线宽较窄、频率稳定度较高的输出激光。该系统能够自动长期稳频，输出激光线宽约为1 MHz，稳定度指标为秒稳定度1.43×10-10，十秒稳定度3.90×10-11，百秒稳定度1.28×10-11，千秒稳定度2.25×10-11。在稳定度略优于商用外腔半导体激光器的前提下，该激光系统电源体积缩小了约85%，整机功耗降低了约90%，为实现半导体稳频激光系统的低功耗和小型化提供了一种新的方案。
激光器 频率稳定度 饱和吸收谱 低功耗 小型化
1 华南师范大学 广东省微纳光子功能材料与器件重点实验室, 广东 广州 510006
2 上海市激光技术研究所, 上海 200233
3 上海市激光束精细加工重点实验室, 上海 200233
为了研究激光熔覆合金层组织性能在高温热处理条件下的变化规律, 利用YLS-4000连续光纤激光器, 采用同步送粉法在Q235钢表面激光熔覆了Ni60、Ni60＋25%WC 两种合金粉末。然后利用SXL-1030型程控箱式电炉对熔覆了两种粉末涂层的Q235钢进行高温热处理, 600 ℃保温10 h。采用光学显微镜、SEM、XRD等研究了涂层的组织和变化, 利用显微硬度计测试了涂层的显微硬度分布, 高温摩擦磨损仪测试了涂层的耐磨性。研究结果结果表明: Ni60合金层金相组织为较致密的针状晶和树枝晶, 经过高温热处理后, 晶粒长大为较大颗粒状, 而且合金层显微硬度和耐磨性只有小幅下降, 表现出良好的抗高温耐磨性; 而Ni60＋25%WC合金层金相组织包含了WC晶粒, 高温热处理后, WC晶粒分布均匀化, 显微硬度和耐磨性得到一定的提高。
激光熔覆 热处理 合金层组织 laser cladding heat-treatment alloy layer
Author Affiliations
Abstract
Institute of Quantum Electronics, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China
Two extended-cavity diode lasers at 780 nm which are longtime frequency-stabilized to Rb87 saturated absorption signals are reported. A high-performance frequency-locking circuit module using a first-harmonic detection technique is designed and achieved. Two lasers are continuously frequency-stabilized for over 100 h in conventional laboratory condition. The Allan standard deviation of either laser is estimated to be 1.3×10-11 at an integration time of 25 s. The system environment temperature drift is demonstrated to be the main factor affecting long-term stability of the stabilized lasers based on our correlation study between beat frequency and system environment temperature.
半导体激光器 稳频 阿伦方差 连续锁定时间 140.2020 Diode lasers 140.3425 Laser stabilization 250.5960 Semiconductor lasers Chinese Optics Letters
2010, 8(5): 496
