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Investigation of the Impact of the Pumping Beam Waist Size and Position on the Efficiency of YVO4/Nd : YVO4/YVO4 Laser Generation 抽运束腰尺寸和位置对YVO4/Nd: YVO4/YVO4激光产生效率影响的研究
IF 1.7 4区 物理与天体物理 Q3 OPTICS Pub Date : 2021-07-16 DOI: 10.1155/2021/5451467
J. Młyńczak, Maciej Zyskowski
This article presents the results of the investigation of the generation efficiency for different sizes and positions of the pumping beam waist inside the active medium of the YVO4/Nd : YVO4/YVO4 lasers. The measurements were carried out for a fixed resonator length of 36.1 mm, a constant pumping power of 1.16 W, and four output couplers with different radii of curvature. According to the knowledge of the authors, such an extended experimental approach is presented for the first time.
本文介绍了YVO4/Nd活性介质中不同尺寸和位置的抽运束腰的产生效率的研究结果 : YVO4/YVO4激光器。测量是在36.1的固定谐振器长度下进行的 mm,1.16的恒定泵送功率 W、 以及四个具有不同曲率半径的输出耦合器。根据作者的知识,首次提出了这样一种扩展的实验方法。
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引用次数: 1
Noise Resilient Local Gradient Orientation for Content-Based Image Retrieval 基于内容的图像检索噪声弹性局部梯度方向
IF 1.7 4区 物理与天体物理 Q3 OPTICS Pub Date : 2021-07-14 DOI: 10.1155/2021/4151482
Samina Bilquees, H. Dawood, H. Dawood, N. Majeed, A. Javed, M. Mahmood
In a world of multimedia information, where users seek accurate results against search query and demand relevant multimedia content retrieval, developing an accurate content-based image retrieval (CBIR) system is difficult due to the presence of noise in the image. The performance of the CBIR system is impaired by this noise. To estimate the distance between the query and database images, CBIR systems use image feature representation. The noise or artifacts present within the visual data might confuse the CBIR when retrieving relevant results. Therefore, we propose Noise Resilient Local Gradient Orientation (NRLGO) feature representation that overcomes the noise factor within the visual information and strengthens the CBIR to retrieve accurate and relevant results. The proposed NRLGO consists of three steps: estimation and removal of noise to protect the local visual structure; extraction of color, texture, and local contrast features; and, at the end, generation of microstructure for visual representation. The Manhattan distance between the query image and the database image is used to measure their similarity. The proposed technique was tested using the Corel dataset, which contains 10000 images from 100 different categories. The outcomes of the experiment signify that the proposed NRLGO has higher retrieval performance in comparison with state-of-the-art techniques.
在多媒体信息的世界中,用户根据搜索查询寻求准确的结果并要求相关的多媒体内容检索,由于图像中存在噪声,开发准确的基于内容的图像检索(CBIR)系统是困难的。CBIR系统的性能受到这种噪音的影响。为了估计查询图像和数据库图像之间的距离,CBIR系统使用图像特征表示。在检索相关结果时,视觉数据中存在的噪声或伪影可能会混淆CBIR。因此,我们提出了抗噪声局部梯度定向(NRLGO)特征表示,该特征表示克服了视觉信息中的噪声因素,并增强了CBIR以检索准确和相关的结果。所提出的NRLGO包括三个步骤:估计和去除噪声以保护局部视觉结构;提取颜色、纹理和局部对比度特征;最后,生成用于视觉表示的微观结构。查询图像和数据库图像之间的曼哈顿距离用于测量它们的相似性。所提出的技术使用Corel数据集进行了测试,该数据集包含来自100个不同类别的10000张图像。实验结果表明,与现有技术相比,所提出的NRLGO具有更高的检索性能。
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引用次数: 1
Analysis of Liquid Crystal Tunable Thin-Film Optical Filters Using Signal Flow Graph Technique 用信号流图技术分析液晶可调谐薄膜滤光器
IF 1.7 4区 物理与天体物理 Q3 OPTICS Pub Date : 2021-07-13 DOI: 10.1155/2021/5513995
A. Athamneh, S. Alboon
In this paper, a liquid crystal tunable thin-film optical bandpass filter is studied and analyzed using the signal flow graph technique. This paper investigates an exact form for calculating the transmission coefficients, reflection coefficients, and the transmission intensity of the filter. The simulation results show the filter performance and the channel shape profile. In addition, the results show the tuning capability of the filter. The signal flow graph technique provides an attractive method for analyzing the thin-film optical filters since it overcomes the difficulty of the refractive index concept in extending to optical applications. Moreover, it simplifies the filter analysis and design process.
本文利用信号流图技术对液晶可调谐薄膜光学带通滤波器进行了研究和分析。本文研究了滤光片透射系数、反射系数和透射强度的精确计算形式。仿真结果显示了该滤波器的性能和通道形状分布。结果表明,该滤波器具有良好的调谐能力。信号流图技术克服了折射率概念推广到光学应用中的困难,为薄膜滤光片的分析提供了一种有吸引力的方法。并且简化了滤波器的分析和设计过程。
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引用次数: 0
Terahertz Characteristics of Magnetic Fluid Based on Microfluidic Technology 基于微流体技术的磁流体太赫兹特性
IF 1.7 4区 物理与天体物理 Q3 OPTICS Pub Date : 2021-06-10 DOI: 10.1155/2021/5599185
Xinyuan Zhao, Guoyang Wang, Siyu Shao, Qinghao Meng, Jiahui Wang, Sijia Zhang, Bo Su, Cunlin Zhang
Magnetic fluid is a new functional material with both liquid fluidity and solid magnetism, which has important application value in medicine, biology, and so on. In this study, terahertz technology and microfluidic technology were combined to investigate the terahertz transmission characteristics of a magnetic fluid in different magnetic fields and different electric fields. In the external magnetic field, the intensity of the terahertz spectrum increased with an increase in the magnetic field intensity, and the response to the magnetic field in different directions was different. Under the applied electric field, the intensity of the terahertz spectrum decreased with an increase in the electric field intensity. This method is convenient for studying the terahertz characteristics of magnetic fluid and provides technical support for in-depth studies of magnetic fluid.
磁流体是一种兼具液体流动性和固体磁性的新型功能材料,在医学、生物学等领域具有重要的应用价值。本研究将太赫兹技术与微流体技术相结合,研究了磁流体在不同磁场和不同电场下的太赫兹传输特性。在外部磁场中,太赫兹光谱的强度随着磁场强度的增加而增加,并且在不同方向上对磁场的响应不同。在施加电场的情况下,太赫兹光谱的强度随着电场强度的增加而降低。该方法便于研究磁流体的太赫兹特性,为深入研究磁流体提供了技术支持。
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引用次数: 2
Experimental Research on Automatic Alignment and Control Algorithm of Spatial Light-Fiber Coupling 空间光纤耦合自动对准与控制算法的实验研究
IF 1.7 4区 物理与天体物理 Q3 OPTICS Pub Date : 2021-05-31 DOI: 10.1155/2021/8481146
Xizheng Ke, Benkang Yin
This study aims to solve the difficulties in the coupling between space light and single-mode fiber (SMF) in free-space optical communication. A fiber coupler based on two-dimensional (2D) piezoelectric ceramics was developed, which uses the stochastic parallel gradient descent (SPGD) algorithm to realize the automatic coupling of space light-SMF. In addition, a spatial light-SMF alignment experimentation platform was built indoors to verify the effectiveness and practicality of the 2D piezoelectric ceramic fiber coupler. The results show that the use of the SPGD algorithm can realize the automatic alignment of fiber position coupling, and the SMF coupling efficiency reaches 52.58% when the system is closed loop. 2D piezoelectric ceramic fiber couplers have unique advantages of low cost, simplified structure, and easy array expansion and can effectively solve the difficulty in the alignment of spatial light-SMF coupling. This study will serve as a significant reference for the research on spatial fiber-coupled array technology.
本研究旨在解决自由空间光通信中空间光与单模光纤耦合的困难。开发了一种基于二维压电陶瓷的光纤耦合器,该耦合器利用随机平行梯度下降(SPGD)算法实现了空间光SMF的自动耦合。此外,在室内搭建了空间光SMF对准实验平台,验证了二维压电陶瓷光纤耦合器的有效性和实用性。结果表明,使用SPGD算法可以实现光纤位置耦合的自动对准,系统闭环时SMF耦合效率达到52.58%。二维压电陶瓷光纤耦合器具有成本低、结构简单、易于阵列扩展等独特优点,可以有效解决空间光SMF耦合器的对准困难。本研究对空间光纤耦合阵列技术的研究具有重要的参考意义。
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引用次数: 2
Scan Mirror Assembly for the Multispectral Scanning Polarimeter of Aerosol-UA Space Mission 气溶胶UA空间任务多光谱扫描偏振仪扫描镜组件
IF 1.7 4区 物理与天体物理 Q3 OPTICS Pub Date : 2021-05-28 DOI: 10.1155/2021/8854505
I. Syniavskyi, Y. Oberemok, Y. Ivanov, M. Sosonkin, V. Kireyev, K. Akinin
In this paper, the scan mirror assembly for the space experiment Aerosol-UA scanning polarimeter (ScanPol) is described. The aim of the Ukrainian space mission Aerosol-UA is to create a database of the optical characteristics of aerosol and cloud particles in the Earth’s atmosphere over a long period of time. The optical characteristics of aerosol and cloud particles are derived from multiangular measurements. Multiangular scanning in ScanPol is provided by scan mirror assembly, which contains a reactive torque compensator electric motor and two scan mirrors, mounted on the shaft of the motor. The control system of the scan mirror assembly enables continuous scanning with a constant speed of the space under investigation. This control system tolerates movements of the orbiting satellite and preserves invariability of its spatial position. The polarimeter ScanPol is designed to acquire spatial, temporal, and spectral-polarimetric measurements simultaneously to minimize instrumental effects and “false” polarizations due to scene movement. Instrumental polarization, introduced by the mirrors of scan assembly, is minimized through the polarization compensated two-mirror scheme which contains two mirrors with orthogonal planes of incidence. In this paper, the polarimetric model of the polarization compensated two scan mirrors is considered. Theoretical calculations are given that substantiate the maximum allowable error of the relative angular position of the mirrors is 15 arcmin (0.25°), and the method of adjustment and control of the angular position of the mirrors is proposed. The polarization properties of mirrors are modelled in the spectral range of 370–1680 nm for bulk oxide-free aluminum. It is obtained that the maximum instrumental polarization of the unadjusted mirror system should be observed at 865 nm, and thus, the polarization characteristics of the scanning system at a given wavelength could be considered as representative for ScanPol in general. The key steps for assembling the unit are illustrated.
介绍了空间实验气溶胶- ua扫描偏振仪(ScanPol)的扫描镜组件。乌克兰“气溶胶- ua”航天任务的目的是建立一个长期以来地球大气中气溶胶和云粒子光学特性的数据库。气溶胶和云粒子的光学特性是由多角度测量得出的。ScanPol中的多角度扫描由扫描镜组件提供,该组件包含一个无功扭矩补偿器电动机和两个扫描镜,安装在电动机的轴上。扫描镜组件的控制系统能够以恒定的速度对所调查的空间进行连续扫描。这种控制系统可以容忍轨道卫星的运动,并保持其空间位置的不变性。该偏振计ScanPol被设计为同时获取空间,时间和光谱偏振测量,以尽量减少仪器效应和“假”极化由于场景移动。仪器极化是由扫描组件的反射镜引入的,通过偏振补偿双反射镜方案,该方案包含两个正交入射面的反射镜,使仪器极化最小化。本文研究了偏振补偿双扫描镜的偏振模型。通过理论计算证实了反射镜相对角位置的最大允许误差为15角分(0.25°),并提出了反射镜相对角位置的调节和控制方法。在370 ~ 1680 nm光谱范围内模拟了无氧化铝反射镜的偏振特性。结果表明,在865 nm处可观测到未调整反射镜系统的最大仪器偏振,因此可以认为扫描系统在给定波长处的偏振特性可以作为ScanPol的一般代表。说明了装配该装置的关键步骤。
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引用次数: 2
Airborne Laser Communication System with Automated Tracking 具有自动跟踪功能的机载激光通信系统
IF 1.7 4区 物理与天体物理 Q3 OPTICS Pub Date : 2021-05-25 DOI: 10.1155/2021/9920368
Xizheng Ke, Hanli Liang
The acquisition, alignment, and tracking system is an important part of airborne laser communication and is the prerequisite and guarantee for the normal communication link. In order to solve the problem of automatic tracking of laser communication links in the airborne environment, the rapid capture, alignment, and tracking of beams between terminals are realized. This article proposes a stepping motor as a control servo system and a four-quadrant detector as an automatic tracking method for the detection unit. The pulse width modulation signal controls the rotation speed of the stepping motor and combines the position distribution of the light spot on the four-quadrant detector to achieve high-precision beam tracking. On this basis, indoor simulation experiments are carried out. After many experiments, the tracking accuracy is better than 2.5 μrad, which shows that the system can be applied to airborne laser communication, and it is verified that this method has good automatic tracking performance for airborne laser communication.
采集、对准和跟踪系统是机载激光通信的重要组成部分,是通信链路正常运行的前提和保证。为了解决机载环境下激光通信链路的自动跟踪问题,实现了终端之间光束的快速捕获、对准和跟踪。本文提出了一种步进电机作为控制伺服系统,四象限检测器作为检测单元的自动跟踪方法。脉宽调制信号控制步进电机的转速,并结合光斑在四象限探测器上的位置分布,实现高精度光束跟踪。在此基础上,进行了室内模拟实验。经过多次实验,跟踪精度优于2.5 μrad,表明该系统可以应用于机载激光通信,并验证了该方法对机载激光通信具有良好的自动跟踪性能。
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引用次数: 5
Study on the High-Birefringence Hollow-Core Anti-Resonant Fiber with Semicircular Cladding 半圆包层高双折射空心芯抗谐振光纤的研究
IF 1.7 4区 物理与天体物理 Q3 OPTICS Pub Date : 2021-05-21 DOI: 10.1155/2021/5520142
Shuo Liu, Yuanwei Li, R. Ma, Linwan Zhao, Jia-kun Lv, Xiaolong Dong
For the purpose of satisfying the demands of polarization-maintaining fibers for fiber optic gyroscopes, this article proposes a semicircular cladding birefringent hollow-core anti-resonant fiber. The influence of structural parameters on the birefringence, loss, and bending loss of the fiber is studied. The simulation results demonstrate that at 1550 nm, the ultimate loss of the fundamental mode of x and y polarization is 1.76 dB/m and 0.93 dB/m, respectively. The birefringence can reach 1 × 10−4, and the wavelength range of birefringence greater than 10−4 can reach 60 nm. This indicates that it has excellent bending properties. The proposed optical fiber has excellent performance in polarization maintenance and can supply ideas for the research of high-precision fiber optic gyroscopes and other optical devices.
为了满足光纤陀螺仪对保偏光纤的要求,本文提出了一种半圆包层双折射空心抗谐振光纤。研究了结构参数对光纤双折射、损耗和弯曲损耗的影响。仿真结果表明,在1550 nm处,x偏振基模和y偏振基模的极限损耗分别为1.76 dB/m和0.93 dB/m。双折射可达1 × 10−4,大于10−4的双折射波长范围可达60 nm。这表明它具有优异的弯曲性能。该光纤具有良好的保偏性能,可为高精度光纤陀螺仪等光学器件的研究提供思路。
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引用次数: 4
Simulation and Experimental Study of Terahertz Wave Transmission Characteristics Based on Periodic Metal Open Resonant Ring Structures 基于周期金属开式谐振环结构的太赫兹波传输特性仿真与实验研究
IF 1.7 4区 物理与天体物理 Q3 OPTICS Pub Date : 2021-05-15 DOI: 10.1155/2021/6663146
Yunpeng Ren, Zhiyu Li, Y. Chen, Yunxia Ye, Zhiduo Xin, Heng Lu, Hanyu Wan, Jianquan Yao
Different open resonant ring structures with substrate of polyimide were designed. The transmission characteristics of the structures for terahertz wave were investigated by simulation and experiment. The results show that the transmission peak of the structures moves to high frequency with increase of thickness of the metal layer. With increase of substrate thickness, the transmission peak moved to low frequency and the transmissivity decreased. The influence of number of “C” shape open resonant rings in the unit structure on the transmission characteristics of terahertz wave was also studied. It is found that when the number of “C” shape open resonant rings increases from one to two, more transmission peaks appeared in the frequency of 0.2–2 THz. The transmissivity of the designed structures was tested by terahertz time-domain spectrometer (THz-TDS). The experimental results showed good agreement to the simulation results.
设计了以聚酰亚胺为衬底的不同开环谐振结构。通过仿真和实验研究了该结构对太赫兹波的传输特性。结果表明,随着金属层厚度的增加,结构的透射峰向高频方向移动。随着衬底厚度的增加,透射峰向低频移动,透射率下降。研究了单元结构中“C”形开环数对太赫兹波传输特性的影响。研究发现,当“C”形开环数从1个增加到2个时,在0.2-2 THz频率出现更多的透射峰。采用太赫兹时域谱仪(THz-TDS)测试了所设计结构的透过率。实验结果与仿真结果吻合较好。
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引用次数: 0
An Appearance Invariant Gait Recognition Technique Using Dynamic Gait Features 一种基于动态步态特征的外观不变步态识别技术
IF 1.7 4区 物理与天体物理 Q3 OPTICS Pub Date : 2021-05-03 DOI: 10.1155/2021/5591728
Hajra Masood, Humera Farooq
Gait recognition-based person identification is an emerging trend in visual surveillance due to its uniqueness and adaptability to low-resolution video. Existing gait feature extraction techniques such as gait silhouette and Gait Energy Image rely on the human body’s shape. The shape of the human body varies according to the subject’s clothing and carrying conditions. The clothing choice changes every day and results in higher intraclass variance and lower interclass variance. Thus, gait verification and gait recognition are required for person identification. Moreover, clothing choices are highly influenced by the subject’s cultural background, and publicly available gait datasets lack the representation of South Asian Native clothing for gait recognition. We propose a Dynamic Gait Features extraction technique that preserves the spatiotemporal gait pattern with motion estimation. The Dynamic Gait Features under different Use Cases of clothing and carrying conditions are adaptable for gait verification and recognition. The Cross-Correlation score of Dynamic Gait Features resolves the problem of Gait verification. The standard deviation of Cross-Correlation Score lies in the range of 0.12 to 0.2 and reflects a strong correlation in Dynamic Gait Features of the same class. We achieved 98.5% accuracy on Support Vector Machine based gait recognition. Additionally, we develop a multiappearance-based gait dataset that captures the effects of South Asian Native Clothing (SACV-Gait dataset). We evaluated our work on CASIA-B, OUISIR-B, TUM-IITKGP, and SACV-Gait datasets and achieved an accuracy of 98%, 100%, 97.1%, and 98.8%, respectively.
基于步态识别的人脸识别由于其独特性和对低分辨率视频的适应性,是视觉监控领域的一个新兴趋势。现有的步态特征提取技术,如步态轮廓和步态能量图像,都依赖于人体的形状。人体的形状根据受试者的穿着和携带条件而变化。服装选择每天都在变化,导致更高的组内方差和更低的组间方差。因此,需要步态验证和步态识别来进行人的识别。此外,服装选择在很大程度上受到受试者文化背景的影响,公开的步态数据集缺乏用于步态识别的南亚原住民服装的表示。我们提出了一种动态步态特征提取技术,该技术通过运动估计来保持时空步态模式。在不同的服装使用情况和携带条件下,动态步态特征适用于步态验证和识别。动态步态特征的互相关分数解决了步态验证的问题。互相关得分的标准差在0.12至0.2之间,反映了同一类别的动态步态特征之间的强相关性。我们在基于支持向量机的步态识别上实现了98.5%的准确率。此外,我们开发了一个基于多外观的步态数据集,该数据集捕捉了南亚原住民服装的效果(SACV步态数据集)。我们评估了我们在CASIA-B、OUISIR-B、TUM-IITKGP和SACV-Gait数据集上的工作,准确率分别为98%、100%、97.1%和98.8%。
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引用次数: 5
期刊
International Journal of Optics
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