平顶激光束诱导薄膜损伤阈值测量系统

为了满足快速、精确、定量地测量薄膜激光损伤阈值的要求,设计了平顶激光束诱导薄膜损伤阈值测量系统.介绍了损伤阈值测量的原理和方法,提出二分查找与顺序查找相结合的能量密度查找方式;根据分光镜的分光比及能量探测器示值求解辐照激光能量,用CCD成像法精密测量了作用在薄膜表面的激光光斑面积;基于小波变换法,通过图像处理精确识别了薄膜的损伤;建立能量密度与损伤几率坐标并进行最小二乘法拟合,对损伤阈值进行了标定.对45°高反射膜分别进行了高斯光束辐照和平顶光束辐照的测量实验,结果表明:高斯光束辐照测量的损伤阈值为9.95J/cm~2,平顶光束辐照测量的损伤阈值为13.98J/cm~2,平顶光束诱导比高斯光束诱导的损伤阈值高40.5%.     

一种用于辉光放电光谱深度分析的激光实时测量新方法

辉光放电原子发射光谱仪可用于物质表面化学成分随深度分布的分析,在镀层分析、金属材料检验等领域有着广泛的应用。文章介绍了辉光深度分析的传统方法和局限性以及实时深度测量技术的近期研究,提出了一种用于辉光放电光谱深度分析的激光实时测量新方法。文章采用激光位移传感器和根据激光测量方法设计的辉光放电光源构成实时深度测量系统,详细阐述了系统的设计方案和技术原理。系统的设计结构能够实现在辉光光谱分析的同时进行激光实时溅射深度的测量。通过实验验证和分析了激光实时测量样品溅射深度过程中产生的光源位移现象。采用双激光器实时深度测量系统对锌合金标准样品进行了溅射深度的实时测量,给出了实时深度测量曲线。通过将溅射面测量曲线与参考面曲线进行叠加,得到了样品溅射坑深度的实际值,与Dektak8型表面形貌仪测量结果一致。     

激光三角法测量中被测物表面特性对测量精度影响的分析

激光三角法测量是现代测量技术中重要的测量方法,但其测量精度受自身系统、环境以及被测物表面特征等因素的影响。针对被测表面的特性是激光三角法产生测量中产生测量误差的主要因素,根据特定颜色所造成误差的重复特性提出了数据标定的改进方法;针对表面粗糙度,通过在光路适当位置安装偏振片有效消除了镜面反射,采用双光路设计有效改善了被测物倾斜带来的误差。最后通过实验验证了改进方法的有效性。     

一种四波长轮换的表面形貌干涉测量系统

针对相移干涉法测量表面三维形貌时深度测量范围受波长限制这一问题,提出一种四波长表面形貌干涉测量系统。通过滤波片的轮换,将白光LED光源的光切换出4个不同波长的光源,并依次进行单波长干涉。为解决多波长干涉图像数据处理,采用基于椭圆拟合的算法,在逐帧逐点的相位计算条件下,运用大小尺度相结合的算法实现高精度宽范围的表面形貌测量。实验结果表明:在深度测量范围扩大到约41倍的条件下,测量经中国计量科学研究院采用粗糙度国家基准校准的方波多刻线样板,得到的表面粗糙度数据与校准数据相比,相对误差为4.09%。说明在一定的深度范围内,该系统能够实现表面形貌的高精度测量。     

应用无衍射贝塞尔光束的固体线膨胀系数测量系统

测量固体线膨胀系数是工程设计中的一项重要工作。这套非接触固体线膨胀系数测量系统利用激光三角法进行了设计。通过采用线阵CCD作为信号传感器来实现自动化测量。通过采用无衍射贝塞尔光束来提高测量精度和增大测量范围。     

激光多普勒测量中信号的误差分析

激光多普勒测量技术在流体以及固体表面测量中得到了广泛的运用。由于影响测量的误差源较多 ,因而在实际的测量过程中 ,激光多普勒测量的精度并不是非常的高。影响测量精度的误差主要是激光多普勒频率增宽 ,高斯光束的干涉以及安装误差。通过控制不同的系统参数 ,可以消除或减小相应的误差     

基于CCD测量激光光束质量M~2

设计并搭建了一套基于CCD测量激光光束质量M2的系统。采用CCD测量激光光束在不同位置处的光束直径,通过非线性最小二乘法拟合测量数据获得光束腰斑直径和远场发散角,再通过公式计算得到激光光束质量M~2。利用本系统测量多组数据,并与专业M~2仪所测的数据进行对比,二者一致性较好,表明采用本实验装置测量激光光束质量M~2可以有效地替代M~2仪。     

基于片光的货车侧面防护栏安装尺寸测量

提出了一种基于片光的货车侧面防护装置安装尺寸的测量方法。将线激光光源和摄像机固定在线性传动机构上,通过装置的线性移动,使激光光束在货车侧表面上产生移动,并用相机采集运动过程中的图像,利用激光三角法原理,对采集到的时序图像进行处理,实现对货车侧表面轮廓的三维重建,从而实现对货车侧面防护装置安装尺寸的测量。该方法避免了在普通视觉二维测量过程中,由于防护栏与前后轮胎不共面而造成的测量误差。通过对搭建的实验平台进行的研究表明,测量误差小于1mm,远小于原二维测量方案测量精度10mm,完全满足系统设计的要求。     

湍流大气传输高斯谢尔光束的到达角起伏

研究了在弱大气湍流起伏环境下以窄带宽高斯谢尔光束为激光光源的大气通信问题,分析了大气湍流强度和光源空间相干度对通信光束到达角起伏的影响.采用窄带宽光场的交叉谱密度函数代替光场互相干函数的近似方法和采用包含大气湍流内外尺度的简化折射率谱密度函数,得出了湍流大气中传输高斯谢尔光束的波结构函数(WSF) 和到达角起伏方差解析近似关系.分析表明,光源的空间相干度和传输光束的湍流扩展是影响高斯谢尔光束的相位起伏结构函数和传输光束到达角起伏的重要因素.     

透射式能见度仪LED光源表面特征对能见度测量的影响

从透射仪的光学测量系统出发,理论分析了光学测量系统光源对透射仪探测光束远场光斑特性的影响。结合LED光源的发光原理,研究了LED光源的表面特征,分析了LED光源表面特征与透射仪能见度测量的关系。通过仿真实验证实了光源表面特征对透射仪探测光束准直和能见度测量稳定性产生影响。研究结果表明,LED光源表面特征会影响探测光束远场光斑能量分布,在50 m基线下,使得透射仪探测光束准直中心发生位置偏移25 mm,接收光强最大变化20%,从而影响透射仪发射端对准和能见度测量。通过加扩散片和光阑限制可以明显改善远场光斑特性,远场光斑中心能量分布趋于均匀,在中心区域内接收光强变化在1%以内。     

高精度激光三角位移传感器的技术现状

三角测量法是一种传统的位移测量方法.随着激光器、光电探测器和计算机的发展,三角测量法有了很多新的进展和应用.对激光三角位移测量系统进行概述和讨论.根据光线的不同入射方式激光三角位移传感器主要分为两种:直入射式和斜入射式.分别介绍了这两种方法的测量原理,并对它们各自的特点进行了比较.最后阐述了高精度激光三角位移传感器的应用方向及发展趋势.     

A method for measuring the thickness of transparent oil film on water surface using laser trigonometry

We present a method for measurement of thickness of transparent oil film on water surface based on laser trigonometry. With an oblique incident mode of single-point laser triangulation ranging system, laser light is incident on the upper and lower surfaces of the oil film being measured and an ellipse light spot is formed on the upper and lower surfaces of the oil film. The two light spots are imaged on an image plane CCD by an imaging lens and the image spot is formed and stored in a computer. The thickness of oil film being measured can be obtained by displacement of the image spot and the configuration parameter of the imaging system. The experiment is conducted using edible peanut oil and diesel oil. The research results show that the method presented in this paper is feasible and applicable to dynamic on-line measurement of oil film thickness of oil spill on sea surface.     

光学投影式三维轮廓测量技术综述

主要用于散射物体的宏观轮廓测量的光学投影式轮廓测量技术可以分为两大类：直接三角法和相位测量法。直接三角法包括激光逐点扫描法、光切法和新近出现的二元编码图样投影法。相位测量法以测量投影到物体上的变形栅像的相位为基础，包括莫尔法、移相法、傅氏变换法等等。本文以基于相位测量和光栅投影法为重点综述了光学投影式轮廓测量技术的几种典型方法，讨论了它们的优缺点，并分析了研究热点和发展方向。     

表面散射光对激光三角法位移测量的影响

三角测量法是一种位移测量方法, 其测量精度不但受到传感器本身因素如光源、探测器、机械结构特性等因素的影响, 还受到被测表面特性如色泽、材料、粗糙度、倾斜度以及外界环境的影响。国内外的一些学者提出了许多提高传感器测量精度的方法, 但这些研究都是针对某一特性表面进行的, 没有涉及到对不同表面的测量时存在的问题。利用随机行走理论对物体表面的散射场进行了分析, 给出了不同粗糙度表面下弱散射光强与散射角及入射角的关系。由于设计制造的传感器量程范围内接收散射光的角度在15°至25°内变化, 因此取20°作为散射角角度, 理论计算模拟的三种不同粗糙面散射光强变化最大能达到300%左右。该结果对于优化激光三角传感器的设计和提高测量精度有一定的意义。     

Method for extracting Bessel-structured light fringes’ center lines in a triangulation measurement system

To accurately extract the center lines of the structured light fringes is of the utmost importance for an active vision measurement system based on the laser triangulation method. The characteristic of the ring-structured light fringe pattern in the triangulation measurement system by a Bessel beam has been analyzed. The normal directions of the fringes are determined by solving the directions in which the change of the gray distribution is the greatest. The positions of the light fringes’ center lines can be obtained in normal directions by using the 2D derivative-sign binary map. The experimental results show that the center lines of the ring-structured light fringes can be accurately extracted with the method and the extracted center lines have a good consistency with the original center lines.     

In situ surface topography measurement method of granite base in scanning wafer stage with laser interferometer

Topography of a granite surface has an effect on the vertical positioning of a wafer stage in a lithographic tool, when the wafer stage moves on the granite. The inaccurate measurement of the topography results in a bad leveling and focusing performance. In this paper, an in situ method to measure the topography of a granite surface with high accuracy is present. In this method, a high-order polynomial is set up to express the topography of the granite surface. Two double-frequency laser interferometers are used to measure the tilts of the wafer stage in the X- and Y-directions. From the sampling tilts information, the coefficients of the high-order polynomial can be obtained by a special algorithm. Experiment results shows that the measurement reproducibility of the method is better than 10 nm.     

An opto-electrical method for measuring the gap of LCD glass plates

We focus on the experimented system development for the measurement of the gap of LCD glass plates. The measurement system includes a laser light source, lens module, image capturing system and the algorithm for calculation of the position of light spots. We emphasize the structure of laser triangulation in an optical system. The software is focused on the algorithm for calculating the position of light point, including centroid calculation method (CCM) and Fourier phase shift (FPS).

Furthermore, to verify the feasibility of the algorithm, we use computer software to simulate experiments. We also discuss the contribution of the noise to the accuracy for the CCM and FPS. To complete the development of the opto-electrical measurement system and to verify the accuracy for the hardware architecture, we use a novel mechanism of multi-track and concentricity, laser light source, lens module, and image capturing system.     

Development of a novel scattered triangulation laser probe with six linear charge-coupled devices (CCDs)

The objective of this paper is to develop an inexpensive, robust, and precise scattered-type triangulation laser probe system with six linear charge-coupled devices (CCDs), that can be used to measure simultaneously the distance and inclination angle of a workpiece surface. The developed system has been configured and assembled based on Scheimpflug's principle. Through the specific arrangement of the six linear CCDs, four different measurement modules for the developed system were possible, namely the standard triangulation probe module, the double triangulation probe module, the pentagon-like triangulation probe module, and an approximately circular triangulation probe module. Angular measurements of an inclined surface were possible using the double triangulation probe module. The measuring range of the developed laser probe was ±2 mm and the resolution was 2 μm/pixel. The performance tests among the different measurement modules of the developed probe and the commercial circular triangulation laser probe OTM3-03 have been carried out. The measurement uncertainty of the developed laser probe system, with respect to different surface roughness and slope, was generally smaller than ±20 μm within the measuring range using the pentagon-like triangulation probe module with the statistical methodology of skewness (S_k) and kurtosis (K_u) analysis by setting the appropriate threshold values for S_k and K_u, respectively. The developed probe has been integrated with a PC-based 3-axis micro-positioning stage to construct an automatic non-contact 3D measurement system and to digitize the 3D profile of a small complex object.