基于分层光学扫描的三维数字化测量技术

采用切削分层光扫描测量与计算机数据信息合成相结合的方法，有效地解决了具有复杂内外腔结构零件的三维数字化测量。该方法比传统三维测量速度快、自动化程度高，能同时准确测量零件内外腔表面，零件边缘测量误差可控制在CCD两个像素内。利用获取的铝合金精密小箱体三维数据，在计算机上重构了零件的三维模型，并用RP技术制造出了零件物理原形。     

基于扫描相机的激光三维成像研究

随着条纹管器件技术的发展,条纹管作为瞬态光学器件的应用不再局限于高速摄影和光谱学研究领域。建立以单狭缝条纹管为核心器件的扫描相机激光成像系统,对目标进行推扫成像,获得原始条纹图像,并进行特征数据提取和三维重建。理论计算出的两目标的距离差与实际距离差较接近,从而验证采用该系统作激光雷达成像的可行性。实验结果表明,基于扫描相机激光雷达具有高分辨率,具有较好的应用前景。     

基于相移的彩色结构光编码三维扫描技术

在物体三维轮廓扫描中,被动式双目立体视觉方法对表面特征不明显的物体难以获取足够的三维信息,针对这一问题,基于双目立体视觉原理,结合主动视觉中结构光投射方法,提出了基于相移的彩色结构光编码方法。该方法将四种颜色按照全排列的相关性质编码产生彩色光栅投射在被测物体表面,依据光栅相位移动增大光栅密度,结合极线约束实现立体匹配,最终获取物体三维数据。结果表明使用该三维扫描技术得到的三维曲面符合原物特征,特别适用于物体三维轮廓的致密测量。     

基于LED扫描的全景三维显示系统研究

利用高速一维LED阵列和圆柱形视差光栅构建了一套360°可视的空间三维显示系统.为了提高它的显示效果,分析了这种系统的成像原理,推导了系统的分辨率、刷新率、显示空间等主要显示参数与系统结构参数之间的关系,并提出了一种提高分辨率的方法.根据分析结果制作了原理样机,同时设计了基于FPGA与并行处理技术的图像传输与分发系统....     

三维形貌测量的扫描相移法研究

物体三维形貌测量中常用的光切法的主要优点是易于实现扫描测量大型物体表面,缺点是光刀中心位置难以精确确定;相移法的主要优点是可以用较宽的光栅提高测量的灵敏度与准确度,具有测量速度快和较好的抗静态噪声的能力,缺点是当待测范围较大时,采集图像的像差较大,不利于大型物面的测量.将这两种方法有机地结合起来,取长补短,提出了一种扫描相移法.实验结果表明,这个方法不但适用于长形大物面的形貌检测,而且又大大地减少了图像采集系统畸变误差的影响,从而提高了检测准确度.     

光学相控阵光束电扫描技术及仿真

光学相控阵技术是一种新型光束偏转及扫描技术,介绍了光学相控阵技术光束电扫描的原理,分析了光学相控阵主要参数及高斯光束替代平行光束入射对偏转效果的影响,研究了三种利用光学相控阵实现多光束扫描的方法。研究结果表明,为了提高光束质量应尽量减小单元周期,增大光学相控阵尺寸和填充率,但减小周期并不能完全抑制栅瓣,而高斯光束取代平行光束入射仅影响偏转光束的角宽度,所研究的三种多光束扫描方法均有效,三种方法各有优缺点。     

三维轮廓扫描法测量透镜曲率半径的实验研究

三维轮廓扫描方法可通过连续扫描透镜表面三维空间形貌,拟合得到其曲率半径值。该方法具有测量精度高、可任意选定测量区域、测量力微弱、对光学表面划伤可忽略等优点。通过实验,研究了三维轮廓扫描法测量透镜曲率半径的精度,并分析了测量区域大小、扫描间距等因素对测量精度的影响。实验结果表明,该方法测量凸、凹球面透镜的曲率半径的相对重复性可达到110-6。     

CG光学扫描全息术和FZP光学扫描全息术分辨率比较

本文通过计算机仿真对ＦＺＰ 光学扫描全息术和ＣＧ 光学扫描全息术的横向和纵向分辨率进行了比较。无论是ＦＺＰ 还是ＣＧ 光学扫描全息术,其系统的分辨率与它们的环数有关,当环数越多时,分辨率越高。对于同样大小的ＦＺＰ 和ＣＧ,ＣＧ 光学扫描全息系统的分辨率比ＦＺＰ 光学扫描全息系统的分辨率要好     

基于扫描白光干涉法的表面三维轮廓仪

在强调表面三维形貌测量重要性的基础上 ,介绍了利用扫描白光干涉法测量表面三维微观形貌的原理及三维轮廓仪测量系统的构成。通过给出的几个测量实例 ,反映了该三维轮廓仪的主要特点 ,适合于大范围、高精度、阶梯面的测量。最后分析了影响其测量精度的主要因素。     

环形光栅光学扫描全息术的研究

为了充分利用光学扫描全息系统的分辨率,提出了用环形光栅扫描物体的光学扫描全是术。其优点是：可以用非相干光源记录扫描全息图,系统为单光路,从而可以提高系统的稳定性。阐明了环形光栅光学扫描全息术的基本原理,并给出了实验结果。     

工业CT在反求工程上的应用

首先介绍了基于工业CT的反求工程技术的基本原理和基本步骤。然后分别从基于曲面分割和基于体素分割这两条基本工业CT的反求技术路线,就近年来国内外相关技术的研究进展,进行了阐述、分析和总结。同时,以一实例来展现两条技术路线的反求结果。最后,对基于工业CT的反求工程技术在实际应用中尚未有效解决的问题进行描述和未来的发展进行了展望。     

A unified-calibration method in FTP-based 3D data acquisition for reverse engineering

Reverse engineering plays an important role in product design and manufacturing due to the need for the improvement of existing products. Acquisition of 3D data of existing products is one of the most fundamental processes in reverse engineering. This paper proposes a unified-calibration method for Fourier Transform Profilometry (FTP)-based 3D data acquisition. In current FTP methods, the system parameters, such as positions and orientations of the camera and projector and the reference plane location, are needed to convert the phase map into 3D coordinates of the object. Generally, it is difficult to measure these parameters directly. Therefore, a calibration procedure is required in current FTP methods. In this research, a novel method is proposed for the calibration. Only one image is used to calculate all system parameters in the proposed method. The experiments show the method is simple and feasible for FTP-based 3D data acquisition.     

Systematic error correction of a 3D laser scanning measurement device

Non-contact measurement techniques using laser scanning have the advantage of fast acquiring large numbers of points. However, compared to their contact-based counterparts, these techniques are known to be less accurate. The work presented in this paper aims at improving the accuracy of these techniques through an error correction procedure based on an experimental process that concerns mechanical parts. The influence of the three parameters, defining the relative position and the orientation between the sensor and the surface, is studied. The process used to build an experimental global model of error is presented and applied to a typical part composed of planes or skewed surface. The systematic errors have been reduced by half in comparison to the reference values, while the random errors have slightly increased. This phenomenon is due to the fact that the errors correction model does not take into account the local response of the laser sensor. A second model, taking into account the local defect, has been developed. Its application to an example of inspection of a mechanical part shows an improvement of the results of the correction.     

工业CT在反求工程上的应用

首先介绍了基于工业CT的反求工程技术的基本原理和基本步骤。然后分别从基于曲面分割和基于体素分割这两条基本工业CT的反求技术路线,就近年来国内外相关技术的研究进展,进行了阐述、分析和总结。同时,以一实例来展现两条技术路线的反求结果。最后,对基于工业CT的反求工程技术在实际应用中尚未有效解决的问题进行描述和未来的发展进行了展望。     

A New 3D Digitizer by Cutting and Scanning Layer-by-layer

A crucial element in the reverse engineering process is to obtain 3D data of the part or its CAD model. A new method is presented in this paper, which combines layer-by-layer cutting and scanning on each cross-section of a part with a milling machine and an image scanner respectively. The method can capture the internal and external profile informations of a complex-shaped part at the same precision simultaneously. When data files of 2D edges are imported into the 3D CAD/CAM package, the 3D data or 3D CAD model is acquired. According to the customers' requirements, the system can reach the highest accuracy of 5.4 μm, and a resolution of 2.7 μm in obtaining the 2D edges. The product is completely made now, on which experiments are conducted, which demonstrate the higher accuracy and efficiency.     

平面三维显示技术的研究现状

平面三维显示技术是近年来最新出现的虚拟现实显示技术,其最大的特点是观察者无需使用任何辅助附加设备,直接用肉眼就可看到屏幕上显示的三维图像。为推进三维显示技术的发展,进一步研究了视差立体成像原理,并据此介绍几种平面三维显示方法及其工作原理,包括障栅立体显示、微柱透镜阵列立体显示、偏振片立体显示和基于微柱透镜立体显示原理的多视点系统,阐述并分析了系统的优缺点。以日本三洋公司的四视角立体显示装置、南京大学的多视点三维显示系统和NEC液晶科技的HDDP三维显示系统为例,描述了国内外该项技术近期的研究现状,分析了存在的技术难点,展望了该应用领域的发展前景。     

基于三维成像技术的四轮定位参数建模方法

鉴于现有四轮定位仪参数求取方法误差大、参数项目少、对测量环境要求高等不足,提出了一种基于三维成像技术的四轮定位参数建模方法;该方法通过双摄像机对目标板拍摄获得的图像信息,应用空间向量方法,求取车体运动状态下的轮轴信息,动态建立四轮定位参数测量模型,解决测量平面的动态建立、测量平台的补偿等问题;经过零标定平台测试,当车轮旋转在18~22°时,定位参数求取方法正确有效,通过实车对比测量验证,平均误差小于0.07°。     

Design of three-dimensional imaging lidar optical system for large field of view scanning

Three-dimensional (3D) lidar has been widely used in various fields. The MEMS scanning system is one of its most important components, while the limitation of scanning angle is the main obstacle to improve the demerit for its application in various fields. In this paper, a folded large field of view scanning optical system is proposed. The structure and parameters of the system are determined by theoretical derivation of ray tracing. The optical design software Zemax is used to design the system. After optimization, the final structure performs well in collimation and beam expansion. The results show that the scan angle can be expanded from ±5° to ±26.5°, and finally the parallel light scanning is realized. The spot diagram at a distance of 100 mm from the exit surface shows that the maximum radius of the spot is 0.506 mm with a uniformly distributed spot. The maximum radius of the spot at 100 m is 19 cm, and the diffusion angle is less than 2 mrad. The energy concentration in the spot range is greater than 90% with a high system energy concentration, and the parallelism is good. This design overcomes the shortcoming of the small mechanical scanning angle of the MEMS lidar, and has good performance in collimation and beam expansion. It provides a design method for large-scale application of MEMS lidar.