基于机器视觉的雷达测角精度评估系统

利用光学成像原理,设计了基于机器视觉的雷达测角精度评估系统,主要包括光学部分(CCD相机)、图像采集部分和图像处理与目标角度信息提取部分等;机器视觉的定位成像和高精度测角,保证了该系统能在紧缩场中对雷达系统进行自动化、高精度、实时的角度测量校准和测量精度评估试验;理论分析和仿真结果表明,补偿由于雷达系统和机器视觉系统安装位置不同引起的角度测量偏差后,在正常的实验测量误差条件下,基于机器视觉的角度测量校准和评估系统能达到0.005°的校准和评估精度。     

机器视觉技术在现代汽车制造中的应用综述

随着机器视觉技术的迅速发展,计算机视觉技术的快速、精确、智能等特性在现代工业的各个领域已逐渐被广泛应用,尤其是在汽车制造业。机器视觉在工业领域的三大主要应用是视觉测量、视觉引导和视觉检测。视觉测量技术通过测量产品关键尺寸、表面质量、装配效果等,可以确保出厂产品合格;视觉引导技术通过引导机器完成自动化搬运、最佳匹配装配、精确制孔等,可以显著提升制造效率和车身装配质量;视觉检测技术可以监控车身制造工艺的稳定性,同时也可以用于保证产品的完整性和可追溯性,有利于降低制造成本。可以预见,随着相机、镜头、计算机等核心硬件性能的提升,以及图像处理、深度学习等软件技术的发展,视觉技术未来在各个领域的作用将更加凸显,发展空间也更加广阔。     

基于机器视觉的细水雾液滴尺寸测量与分析

为了满足科研与工程中对细水雾液滴尺寸测量的高精度低成本要求,对雾滴尺寸的机器视觉测量方法进行了深入研究.在自行建立的高压喷雾系统与雾滴采集装置上对细水雾液滴进行了采样,用显微镜及其CCD相机对雾滴样本进行了图像采集,用图像处理软件对采集的雾滴图像进行了处理与分析,测量并统计了5966个雾滴,得到了雾滴尺寸的频谱分布和累积分布以及雾滴平均直径和特征直径,将测量结果与相位多普勒粒子分析仪(PDPA)的测量结果进行了比较.结果表明,机器视觉方法町测量的最小雾滴直径约4.39 μm;机器视觉测量结果与PDPA测最结果相当接近,两种方法测得的细水雾液滴平均直径和特征直径的相对误差均在5%以内,雾滴尺寸均匀度指数的相对误差为0.27%.     

机器视觉测量中成像系统光瞳球差对测量影响的研究

光瞳像差的存在会导致实际光瞳和理想近轴光瞳的形状和位置出现差异,从而对光学系统的成像质量产生间接的影响。由于光瞳球差会影响光瞳的位置,而在某些使用机器视觉的测量系统中,入瞳位置作为摄像机的光心,形成了机器视觉中的一种重要参数,当入瞳位置发生变化时,将会影响到测量的准确性,尤其在高精度的测量领域。介绍了光瞳像差的基础理论,以SCOTS(Software Configurable Optical Test System)光学面形测量系统为例,通过计算入瞳球差,分析了光瞳球差对相位测量偏折术测量的影响。结果表明,双高斯物镜中光瞳球差的存在,对测量结果的准确性和精度造成了影响,故在使用机器视觉进行测量的系统中,需考虑光瞳像差带来的影响。     

机器视觉在激光干涉测量d31中的应用

提出一种应用机器视觉技术的激光干涉法, 可以研究压电材料的逆压电系数. 在传统干涉测量法中引入机器视觉实现干涉图像灰度最佳估计, 使用数字图像处理技术, 一方面应用降噪算法有效去除激光干涉图样中的噪声, 从而确定激光干涉场的光强分布, 另一方面将干涉图样的明暗变化进一步转化为可量度的灰度变化以提高测量分辨力. 通过合理设计算法, 该方法中对位移的理论测量分辨力可以提高达一个数量级, 为干涉光波长的1/1024, 因此在逆压电系数d₃₁ 的实验测量中可以有效提高分辨力. 关键词： 机器视觉 逆压电系数 双光束干涉 数字图像处理     

线结构激光-机器视觉三角测量光路设计

给出了线结构激光 -机器视觉三角测量的通用光路计算公式。公式考虑了激光入射角、CCD面阵与光轴的各种变化情况 ,对激光机器视觉测量系统的光路结构设计有一定的指导意义。     

机器视觉精密测量系统研究

微小孔系的精密测量用传统的手段是难以实现的。以机器视觉为基础,结合计算机图像处理技术可完成这类测量任务。介绍了基于机器视觉的孔系精密测量系统的硬件组成和图像处理算法。以所提出的识别弦端点来确定图像圆心坐标的算法对500根弦的中点坐标进行滤波处理,可使识别误差达到亚像素级。圆心坐标在X和Y方向的标准差均小于4μm,孔系间角度测量标准差小于3″。     

机器视觉应用中物体离焦及过厚对测量精度的影响

机器视觉技术在工业测量中具有广泛应用,实现高精度的机器视觉测量对精密加工、制造具有重要意义。针对机器视觉应用中待测物体偏离焦面及在纵深方向过厚导致测量结果出现误差的问题进行了研究。重点讨论了系统中镜头远心度引起的平行性误差及其对离焦物体测量结果的影响。实验结果表明,在物体偏离最佳成像面而引入的误差中,平行性误差占到90%左右,因此可通过后期对平行性误差进行补偿以较大程度地提高系统测量精度。此外,针对待测物体过厚导致边缘模糊这一问题采用多种边缘检测算法进行了分析。结果表明在一定范围内,物体纵深方向越厚,边缘检测误差越大。在这一结果的基础上,对算法进行改进,提出一种基于图像灰度曲线的补偿方法,使测量误差由超过20μm降至10μm以下。     

第3届西安机器视觉与工业检测展览会将在10月举行

据悉,第3届西安机器视觉与工业检测展览会今年10月将如期在西安光电园举行。西安机器视觉研究发展中心已经成功举办了首届和第2届视觉展会。为了推动机器视觉技术及产业的发展,西安机器视觉研究发展中心将于2007年10月18-19日举办第3届西安机器视觉与工业检测展览会。展会期间将举行丰富多彩的交流活动,并充分宣传和展示机器视觉行业的最新发展、最新成果、最新产品,促进机器视觉企业与用户在项目和技术上的合作,介绍和交流国内外机器视觉产业发展的新趋势和新应用,广泛宣传和研讨机器视觉的工业应用问题,提高机器视觉企业和产品的知名度,为…     

基于图像处理技术测量马铃薯表形特征

利用机器视觉和图像处理技术对马铃薯的表形特征进行测量,通过测量马铃薯投影面积、缺陷面积和投影周长,对马铃薯进行品质检测.该研究可以作为检测马铃薯表形品质检测的基础.     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Research on beamforming method for dual-line array with space mismatch between the two line arrays

The performance of port/starboard discrimination of dual-line array will be seriously degraded when the space between the two line arrays of the dual-line array is mismatched. The directivity function of the delay-sum and delay-subtract beamforming is deduced and the port/starboard discrimination of the delay-sum and delay-subtract beamforming is also studied both under the ideal status and the status under which the space between the two line arrays of the dual-line array is mismatched. Analysis results show the delay-subtract beamforming has better performance of port/starboard discrimination. At last, the sea trial results demonstrate the theoretical results.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Retrieval of ultraviolet skylight radiances and O3 slant column densities from balloon-borne limb spectrometer

With a novel light-weight and absolutely calibrated ultraviolet （UV） spectrometer, UV skylight radiances and O3 slant column densities are measured by balloon-borne limb measurements in Xinjiang area, China. UV skylight radiances measured at the height of 31 km are compared with the results from Modtran in the wavelength range from 290 to 420 nm. O3 slant column densities are derived from radiance spectra in the Huggins bands （320 - 335 nm） using differential optical absorption spectroscopy method. And the parameter exhibits a good correlation with the same value simulated by radiative transfer model （Tracy）. The O3 profile simultaneously measured by an O3 sonde is used as input in Tracy calculations. The O3 sonde is launched on the same balloon.     

Design optimization of highly sensitive LSPR enhanced surface plasmon resonance biosensors with nanoholes

For breaking through the sensitivity limitation of conventional surface plasmon resonance (SPR) biosensors, novel highly sensitive SPR biosensors with Au nanoparticles and nanogratings enhancement have been proposed recently.But in practice, these structures have obvious disadvantages.In this study, a nanohole based sensitivity enhancement SPR biosensor is proposed and the influence of different structural parameters on the performance is investigated by using rigorous coupled wave analysis (RCWA).Electromagnetic field distributions around the nanohole are also given out to directly explain the performance difference for various structural parameters.The results indicate that significant sensitivity increase is associated with localized surface plasmons (LSPs) excitation mediated by nanoholes.Except to outcome the weakness of other LSP based biosensors, larger resonance angle shift, reflectance amplitude, and sharper SPR curves' width are obtained simultaneously under optimized structural parameters.     

Polymer gratings based on photopolymerization for low-order distributed feedback polymer lasers

Novel polymer distributed feedback(DFB)gratings are fabricated based on photopolymerization to reduce lasing threshold of polymer lasers.A photopolymer formulation sensitive to 355-nm ultraviolet(UV)light is proposed for the fabrication of polymer gratings and it can be used to form polymer films by spin-coating process.A very low surface-relief depth ranging from 12.5 to about 1.0 nm has been demonstrated with a refractive-index modulation of about 0.012.The experimental results indicate that such polymer gratings have promising potentials for the fabrication of low-order DFB organic semiconductor lasers.