激光波高测量中示踪粒子性能分析

激光测量流体波动的波面高度,其基本原理是将激光投射到流体表面,通过计算投射距离,反演出波面高度。由于投射目标是气液的界面,,因此需要在接收激光投射的目标流体表面加用反射物质,以正确显示波面位置。通常采用反射示踪粒子撒播在被测流体表面,这是波高测量系统中的重要组成部分。本文通过对比不同示踪粒子反射性能的实验结果,分析所测示踪粒子的效果,对不同示踪粒子的特点、存在问题给出鉴定与讨论,并归纳出良好的波面反射示踪粒子应具备的特性。特别指出在气液交界面不宜使用气泡为示踪粒子及其原因。     

基于摩擦磨损特性的激光表面造型试验研究

通过球墨铸铁材料圆环端面的激光造型,对比光滑表面、点圆和网格造型图案对材料摩擦磨损性能影响,发现同样分布率的网格造型图案有较好的抗磨损特性和承载性能.通过比较不同激光加工参数和网格几何参数的激光造型表面的形貌和摩擦磨损特性,找到激光造型的优选方案.     

用变形光栅条纹自迭加法测曲率

用变形光栅条纹自迭加法测曲率谭吉春（国防科技大学应用物理系）０引言应用莫尔条纹原理测量物体三维尺寸时，实验装置中通常有两块光栅。第１块称作物光栅。用投影光学系统将物光栅图案投射到被测物表面，生成变形光栅图案。此图案含有物体表面高差信息。第２块光栅称作...     

基于TwinCAT的压印转移设备电子凸轮的设计

分析了激光图案压印转移设备的结构及其运动功能需求。针对压印转移设备的伺服控制,研究了基于TwinCAT的凸轮表设计和电子凸轮的应用,实现了压印转移设备中各轴运动的耦合;为实现激光图案压印转移设备的自动化和数字化提供技术支持。     

基于CATIA二次开发的微透镜阵列仿真

汽车灯具的发展日新月异,近年来出现的新型灯种Logo灯逐渐流行。Logo灯可根据客户要求投射出各种图案,其原理是将光源发出的光通过灯内微透镜阵列投射至地面,但由于地面与光源透镜不平行,图像倾斜投影时会产生畸变失真现象,因此光学设计需要对光源图形进行修正才能避免失真。详细介绍如何通过CATIA二次开发对Logo灯的微透镜阵列进行仿真。     

带装夹变形曲面表层图案的精密加工

高精金属层图案是高性能天线等构件的关重服役结构,由于其薄壁曲面、微米级层厚和基底材料广泛等特点,多采用激光加工制备.然而该类构件的稳定装夹会诱发曲面的弹性变形,致使实际加工中光束偏焦,影响表层图案的加工精度.为此,通过分析薄壁曲面装夹变形,研究原始激光加工轨迹向变形曲面的映射求解方法.实验表明,图案蚀深和蚀宽误差的抑制...     

嵌入式结构光投射系统设计

结构光投射系统的设计搭建是结构光三维形貌测量系统成功实现的关键之一.传统的激光投射系统存在结构复杂、生成的结构光的质量较低等缺点;而常用的光学投影系统又存在不完全可控等缺陷,难以适应嵌入式的应用.设计搭建了基于自主设计的嵌入式实时数字微镜(DMD)模块的结构光投射系统,驱动电路自主设计,底层接口完全可控,实现了结构光投...     

基于Gray码和线移条纹的结构光3D测量技术

结构光3D测量的线移条纹进行编码,以亚像素定位技术提取Gray码条纹边缘和线移条纹中心,将其上点作为图像采样点进行解码的方法.消除了Gray码固有的一位解码误差对投射角求取的影响,同时提高了采样密度.文中具体介绍该方法的编码解码原理,分析了编码图案正交投射对测量准确度的影响,给出了仿真实验结果.测量误差约为0.04%.     

图像目标搜索区域自动定位方法及其在视觉线扫中的应用

主动式线激光三角技术的三维重建广泛地应用于工业测量领域,对于图像中目标激光影像的搜索和定位尤其重要,搜寻区域的大小影响着计算效率。本文根据激光器投射模型,以投射点为基准提出一种图像中目标所在区域的自动划分方法。在每张图像中自动定位搜索区域,在保证目标完整的情况下能够有效地缩减搜索区域,提高搜索效率,同时避免常规的按行(列)搜索方法所产生的拍摄角度重叠问题。     

一种线宽可调的激光标线仪

详细介绍了利用柱透镜准直的激光标线原理.激光标线仪的主要性能指标之一激光线的弯曲度,对激光标线的弯曲度误差作了分析,得出了激光光源和柱透镜的位置关系是影响弯曲度主要因素.为保证圆柱透镜和投射激光束的位置关系在正透镜调整圈端部设计一个定位柱面,和镜筒内孔的圆柱面相配合,保证了正透镜调整圈和镜筒的同轴度,一般的结构是镜调整...     

Surface texture assessment of ultra-precision machined parts based on laser speckle pattern analysis

Surface texture plays an important role in overall product specification, because the surface quality of the product is dominated by the nano-scale surface texture. This paper presents a surface texture assessment method for evaluating roughness and periodicity of surface structure with a laser speckle pattern analysis. By investigating the relation between surface texture and laser speckle pattern, characteristic parameters for describing a laser speckle pattern are proposed. The proposed characteristic parameters can evaluate the surface texture in entire observed area and in limited area in any given direction. Furthermore, the surface texture can be qualitatively assessed with a radar chart of the proposed laser speckle characteristic parameters.     

Weld Pattern Design for Sheet Metal Laser Welding Considering Fixturing Quality

In sheet metal assembly by laser welding, metal fit-up is an important specification for achieving welding quality. The fixture plays an important role in satisfying the intimate metal fit-up that laser weld requires. The fixturing quality for sheet metal laser welding is directly related to the assembly weld patterns used (weld location, weld length, etc.). The design of assembly weld patterns is a critical phase in the fixture design cycle. Traditionally, the determination of the weld pattern is based on the designer’s experience. Because of this it is quite easy to cause unexpected deviations from the assembly weld quality requirements. In this study, a new computer-aided design approach for the assembly weld pattern is developed, where the sources of variation in the weld areas of the parts are considered in detail. Using this approach, the weld location and the weld length obtained are much more reasonable and cost-justified. A simple example and a case study show that the approach presented for assembly weld pattern design can reasonably meet the fixturing quality requirements.     

激光显示中散斑的减弱

为减弱激光显示中散斑的影响,在对散斑对比度进行理论分析的基础上,提出了一种利用位相光学元件减弱散斑的方法。实验以绿光为光源,让激光束通过位相光学元件,再经过CCD相机和图像处理系统处理,得到屏幕上散斑对比度和光强的变化。实验结果表明:散斑的对比度降低到3.7%,可满足激光显示中对散斑减弱的要求。该方法具有简单易行、成本低、适合批量化生产等优点。     

激光器在数字散斑干涉系统中的应用

介绍了在数字散斑干涉系统中经常使用的激光器 :He- Ne激光器、半导体激光器和 LD泵浦的固体激光器 ,总结了这几种激光器在数字散斑干涉系统中的应用原理 ,对比了各自的优缺点 ,并提出了一种新的应用领域——在采用数字散斑干涉技术的机器人口型识别系统中 ,应用微片激光器作为光源 ,对该激光器作了分析介绍 ,讨论了它的特点。     

汽车缸套激光硬化处理后的组织与性能

研究了汽车缸套激光硬化处理后的性能及组织特点。研究结果表明：采用激光硬化处理可明显提高缸套的硬度。其硬化组织主要为隐晶马氏体,片状石墨基本保持原形貌不变。     

工程塑料表面金属覆层的激光定域精细去除

结合激光刻蚀手段与数控加工技术,提出了一种基于数控激光铣削的工程塑料表面金属覆层定域精细去除方法。考虑不同位置的零件对加工质量的要求不同,通过激光烧蚀实验结果得到了保证图形边缘质量的精密切边加工工艺并确定了相应的工艺参数。开发了基于实际进给速度自适应调整激光能量的覆层金属定厚度高效去除技术,完成了图形内部余量的去除,解决了机床实际进给速度受动态性能限制无法达到预设值而导致的目标材料过烧蚀问题。最后,以典型零件复合式三维信号发送/接收器为例,通过对工件图形分区域变参数加工验证了所提出的方法的可行性。实验结果表明:采用基于数控激光铣削的金属覆层定域精细去除技术能够完成典型样件的精密加工,加工的三维金属图形衔接精准,边缘光顺整齐,热影响区范围小,能够满足该类零件高质高效的制造要求。     

Optical method for flow patterns discrimination,slug and pig detection in horizontal gas liquid pipe

An optical method including infrared ray and laser was developed to discriminate flow pattern, and detect liquid slug and pig in horizontal gas–liquid pipe. Based on the principle that infrared ray attenuates differently during penetrating gas and liquid, the infrared ray method was developed to discriminate flow pattern and detect liquid slug. In experiment, infrared ray was emitted on one side of the transparent pipe, and detected on the other side. Simultaneously, a signal of output voltage that is proportional to the intensity of infrared ray detected was generated and recorded. A series of experiments in horizontal air/water loop were carried out to generate bubble, stratified smooth, wavy and intermittent flow, and the output voltages under the four flow patterns were analyzed. The flow patterns can be discriminated by characteristics of output voltage. Meanwhile, the velocity and frequency of liquid slug were measured by this method, and the results were consistent with that calculated by formulas. However, infrared ray is easily affected by interface between gas and liquid, a laser method was explored to detect pig. The laser method is similar to infrared ray, a laser beam was emitted and detected and then a signal of output voltage was recorded. The results from pigging experiments show that the laser method could correctly detect the passing of a pig. The combined use of infrared ray and laser method could rightly detect pig and pigging slug during pigging operation.     

运用3D数字化模型的轮胎花纹检测

针对轮胎花纹的几何形状,提出基于3D数字化模型的检测方法。利用测量设备REVscan激光扫描仪获取轮胎花纹的表面数据,并利用Geom agic Qualify软件对获得的数据进行检测,检测结果以图文方式直观进行显示。该研究为轮胎花纹的检测提供了方便、快捷的方法。     

Temperature and stress analysis and simulation in fractal scanning-based laser sintering

A model for calculating the evolution of temperature and thermal stresses within a single metallic layer formed on the powder bed using different scanning patterns in selective laser sintering (SLS) was proposed. The model allows for the non-linear behavior of thermal conductivity, specific heat, and elastic modulus due to temperature changes and plastic deformation capabilities with a bilinear isotropic hardening behavior. The effect of laser scanning patterns on temperature, residual thermal stresses and distortion were investigated. It was shown that the distortion and transient stresses of a layer processed by a moving laser beam is decreased with fractal scanning pattern.     

激光扫描系统中f-θ透镜的光学设计

在激光扫描系统中f-θ透镜是重要的必不可少的部件,它在激光打标机、传真机、印刷机和用于制作半导体集成电路的激光图形发生器以及激光扫描精密计量设备等等光电系统中得到广泛的应用。文中设计了用于非接触在线检测工件尺寸的f-θ透镜。这种透镜的特点是一种负畸变透镜,属于像方远心光路,工作波长为单色光,像质要求波像差要小于λ/4,而且要求整个像面成平面且像质一致,无渐晕存在。所设计的f-θ透镜结构简单紧凑、焦距小、扫描精度高、加工成本较低,性能达到衍射极限,并具有像面上照度分布均匀,能量集中度高和相对畸变小等优点。