The direct measurement of the power spectrum of rough surfaces by optical fourier transformation

Conditions which allow the reliable measurement of the power spectrum of opaque rough surfaces by direct optical Fourier transformation were determined. The relation of the spectrum of the surface irregularities to the optically observed spectrum is discussed and the experimental results obtained to date with a transform apparatus are presented. Consideration is given to the range of roughness values to which the method may be reliably applied.     

Rapid measurement of surface roughness for face-milling aluminum using laser scattering and the Taguchi method

In this paper, an experimental model for the rapid measurement of surface roughness (R_rms) in CNC face-milling specimens using the laser speckle method and digital image processing is established. The specimens used in this study were made of 6061-aluminum alloys through the high-speed face-milling process. In order to evaluate the effect of machining conditions, such as the feed rate, the spindle speed, the depth of cut, and the material of the cutting tool on the roughness of the specimens, the Taguchi method was used to determine the optimal parameters for machining. The laser radiation results in the speckle structure formed in the space when coherent light is scattered through an optically rough surface. The features of the speckles depend on the characteristics of the rough surfaces. Hence, the experimental work for the roughness measurement is based on the speckle effect. The experimental setup in this study consisted of a He-Ne laser, a ground glass, a CCD camera, and a digital image processing system developed using the Virtual Basic language. Computer evaluation of the speckle images revealed the values of R_rms rapidly. This study proposed a precise and non-contact optical method for evaluating the surface roughness from 0.20 to 0.60 μm.     

基于6-SPS并联机构自由曲面非接触测量方法的应用研究

针对自由曲面的测量方法，分析了传统的直角坐标型三坐标测量机存在的缺陷，提出了以并联机构作为测量机的机械结构和图像处理技术为基础的非接触测量方法。阐述了其基本原理．推导出计算公式．并运用图像处理技术．对目标图像进行处理，计算了光斑的重心坐标。     

Phase Retrieval with a Diffractive Micro Lens Array

Multi-plane phase retrieval is a well established technique for reconstructing both, amplitude and phase of an object wave. This standard technique works best, if the intensity of the object wave changes rapidly along the optical axis. For slowly varying intensities, the iterative procedure may not converge at all. To overcome this limitation we combined the standard technique with a periodic phase element. We demonstrate that a binary diffractive micro lens array with overlapping aperture significantly improves the convergence of phase retrieval and thus the quality of reconstruction. Thus multi-plane phase retrieval can be applied for both rough and smooth phase distributions.     

融合SFS和主动视觉技术的未知物体重建方法

针对未知三维物体自动重建问题,提出一种结合明暗恢复形状的被动视觉和主动视觉技术的新颖三维重建方法.首先利用摄像机分别获取初始位置及旋转180°位置下的未知物体图像信息,采用改进的Tsai-SFS算法恢复物体表面粗糙轮廓,从而获取未知物体的最大尺寸信息.然后结合单目线激光主动视觉系统沿Z轴旋转方向和绕X轴翻转方向上的可视空间模型,预测出物体未知区域信息.最终依据下一视点的可见性判据,将规划过程分为物体侧表面重建规划和上表面重建规划.其中将能获取最大可视曲面面积和最佳表面重建精度的位置定义为下一最优视点位置.并经过实体模型的三维重建验证所提方法的可行性及有效性.     

反射温度补偿法及其实验验证

为补偿环境辐射对红外测温的影响,根据红外辐射理论和红外热像仪的测温原理,提出了反射温度补偿法。介绍了该方法的原理,给出了该补偿方法的理论计算公式。相关实验显示,在被测物体周围存在高温物体的情况下,采用提出的反射温度补偿法可补偿高温物体的反射能量。红外反射镜的选取与被测物体的表面状况有关,若被测物体可视为朗伯体,则可选铝箔为红外反射镜;若被测物体为非朗伯体,则需选用与被测物体表面结构相似的材料为红外反射镜。经过反射温度补偿,能较为准确地得到朗伯体的表面温度,误差可控制在2%以内;该方法亦能够较大地提高对非朗伯体的测温精度,其误差不超过5%。这些结果表明该方法简单易行,精度较高,适用于大部分的红外热像仪。     

Simulated Effects of Measurement Noise on Contact Measurements Between Rough and Smooth Surfaces

To test the accuracy of optically measuring contact, we examined the height distribution histogram of a simulated rough surface contacting a smooth surface. We qualified the technique sensitivity as a function of the inverse signal-to-noise ratio having values ranging from 0 to 0.3. An explanation of how the analysis technique can be applied to Dual Emission Laser-Induced Fluorescence (DELIF) measurements is provided.     

Prediction of contact parameters from the topographies of contacting surfaces

An image analysing technique has been used to examine the distribution of sizes of micro-contacts produced by impressing hard, rough surfaces into soft, optically flat surfaces. Comparisons with a statistical theory of contact indicated the correct values of mean surface slope required for the accurate prediction of the microscopic contact configuration.     

Determination of the profile of the surface of a test object during automated nondestructive ultrasonic testing in the immersion mode and reconstruction of flaw images using the SAFT method

The problem of using an elastic organosilicon polymer (??aquapolymer??) as an immersion medium for providing a stable acoustic contact between a test object and a piezoprobe in the process of automated ultrasonic testing of objects with rough surfaces is considered. The use of an ??aquapolymer?? allows one to decrease the consumption of water during ultrasonic testing. Flaw images were reconstructed using a modification of the SAFT method, which takes the profile of a test object into account; this allows improvement of the image quality. An algorithm for obtaining information on the profile of the surface of a test object and taking this profile into account during reconstruction of flaw images with the SAFT method is proposed. Model experiments yielded flaw images with the refraction of beams on a rough surface taken into account.     

Characterization of Local 3-D Rough Dielectric Surfaces Using Standoff GPR Measurements with Widebeam Antennas

In real life most ground surfaces are not flat but rough. The observation of surface roughness depends on the wavelength and angle of the incident wave. In order to be able to detect shallow subsurface objects, on one hand we need to use higher frequencies to achieve better range resolution. One the other hand we have to deal with rough surfaces relative to shorter wavelengths. In this paper a wideband ground-penetrating radar (GPR) phase measurement and processing technique for characterizing three-dimensional (3-D) rough dielectric surfaces is presented. The method is based on the measurement of phase data by a standoff GPR with wide-beam antennas at short range over 3-D rough ground surfaces. The principle of this method was verified experimentally in the measurement of a composite surface. The height of the composite surface varies from 0 to 8 cm. The antennas are open-ended waveguide antennas whose frequency range is 2.3 GHz to 4.3 GHz. They are broadband, have low gain and wide beamwidth. The experimental tests demonstrate that the 3-D rough surfaces can be characterized locally by using a monochromatic and multifrequency broadband phase processing and imaging method. The results show good agreement between the imagery of the surface height distribution obtained by this method and the actual geometry of the 3-D rough surfaces.     

基于场曲的物像间曲直面的换算及其应用

从点源圆孔衍射的成像原理出发,经过适当推理得到仅有场曲像点的光强和位置的计算式,进而分析探讨了基于场曲的物像间曲直面的换算原理与方法及其应用。该方法有利于光学设计中对场曲进行像差平衡与校正、光学加工中对场曲的检测与修正、数码成像时做场曲的电子校正以及虚拟测量中的曲直面换算等。     

粗糙表面的机器人磨削实验与分析

组建了由MOTOMAN机器人、六维力(力矩)测量系统和振动测量组成的粗糙表面磨削实验平台，进行了磨削力的测量及振动的测试，分析了MO-TOMAN磨削机器人系统的磨削力及振动响应。结果表明，粗糙表面磨削与普通表面磨削的显著区别是：切向磨削力与法向磨削力不成比例，切向磨削力可能比法向磨削力大很多；影响切向磨削力大小的最主要因素是被磨削材料的表面质量，表面越粗糙，则切向磨削力越大。     

A new approach for determination of a mean speckle size in simulated speckle pattern

In this paper one-dimensional correlation method for determination of a mean speckle size is used, while two various approaches are presented. It is shown, that accuracy of the measurement by the method depends on a number of speckles in an evaluated one-dimensional intensity profile of detected speckle pattern. It is also shown, that a significant optimization of the method by reduction of a number of intensity values representing detected speckle patterns can be performed. This study is carried out for several speckle patterns generated through a numerical simulation of the speckle fields after reflection of a Gaussian beam off a rough object’s surface. Results of the determination of the mean speckle size are compared with theoretical predictions.     

粗糙表面精度测量系统的研究

设计了一套粗糙表面精度测量系统,采用线边缘激光三角法实现了亚像素级测量,在图像算法上采用改进的阈值法进行边缘检测,用形态滤波法对被测物表面图像进行处理。研究结果表明,该系统能较好地提高测量精度,并得出较满意的图像边缘,可达到5 m的测量精度要求,且具有一定的通用性,实现了对具有粗糙表面的电池极片涂敷层的厚度及均匀性的测量。     

基于二维连续小波变换的三维轮廓测量技术比较研究

为解决在物体高度梯度变化较大的情况下三维轮廓测量技术的测量精度问题,将连续小波变换应用到三维轮廓测量技术中.开展了基于2d-paul和2d-morlet连续小波变换轮廓术研究,进行了三维轮廓测量术比较分析,建立了小波“脊”相位与高度之间的关系,提出了在物体高度梯度变化较大的情况下基于2d-paul算法优于2d-morlet算法.在对比分析的基础上对两种连续小波变换轮廓测量技术的测量精度进行了评价,进行了Matlab和实测试验.研究结果表明：物体高度梯度变化较大的情况下适合采用2d-paul算法,其能更有效地提高三维轮廓测量技术的测量精度.     

表面粗糙材质的复折射率反演

由于目标偏振特性研究中表面粗糙材质的复折射率很难准确反演,本文对常用的Vimal-Milo反演法进行了改进。分析了粗糙表面的偏振二向反射特性,指出了Vimal-Milo法采用的"偏振度-角度相关"反演模式的不足。然后,提出了基于"相对偏振分量-角度相关"的反演方法 ,推导出复折射率的反演公式,并设计了对应的全局搜索算法。最后,利用绿漆及铝板的偏振特性测试数据,对提出的复折射率反演算法进行了验证,并基于此对偏振二向反射特性进行了正向推演验证。反演数据表明:使用本文提出的复折射率反演方法,表面粗糙铝板的复折射率的反演精度较Vimal-Milo法有了显著提高,实部和虚部与真值的误差均在±0.01以内,且评价因子小于0.07;推演数据表明:表面相对光滑的绿漆的偏振二向反射亮度的推演结果为Vimal-Milo法得到的均方根误差的1/5,与测试数据的误差在0.01以内。得到的结果证明本文所提复折射率反演方法可用于光滑及粗糙表面材质的复折射率反演。     

超低速动平衡测量技术研究

旋转体的质量均衡是保证其良好运行的重要参数。针对立式离心机的动平衡测量提出一种新方法,给出这种方法的理论推导,描述了基于这种新的动平衡方法而设计的测量系统。实验证明,新的动平衡测量方法是有效和实用的,整套测量设备工作稳定、测量精度高。     

齿根三维粗糙表面的应力集中系数计算研究

考虑粗糙表面影响因素的齿轮齿根处应力集中系数计算是齿轮弯曲疲劳寿命精准预估的难题,以磨削喷丸后的直齿轮为研究对象,研究粗糙表面下的齿根应力与应力集中计算问题。采用白光干涉仪Wyko NT9100对磨削喷丸齿根粗糙表面进行测量,得到粗糙表面形貌数据,基于空间坐标变换原理,使用Python对有限元软件进行二次开发,通过调整齿根细化网格节点坐标实现了齿根表面粗糙形貌的添加工作,建立了齿根过渡曲面三维粗糙表面有限元模型并进行仿真分析。通过数值计算得到三维粗糙表面参数下的齿根应力分布与应力集中系数,对粗糙表面参数与应力集中系数的关联规律进行非线性回归分析,建立粗糙表面参数与应力集中系数的关联规律。结果表明,粗糙表面参数S_a、S_v、S_10z拟合应力集中系数得到拟合公式的相关系数分别为0.799,0.784,0.914,十点区域高度参数S_10z能较好地表征齿根表面的应力集中。     

表面粗糙度测量仪工作台设计探讨

传统的触针式轮廓仪,由于易造成表面的损伤,以及只能在实验室环境下使用;而且测量时间较长,已不能满足需要。而一种非接触性的,测量快速、简便,甚至能实现在线或过程测量的表面粗糙度测试方法,则显得具有十分重要的意义。通过对现有触针式轮廓仪工作台的改进的研究,来实现对工作表面粗糙度的非接触式测量。它采用一种新型光纤传感器来测量表面粗糙度和微位移。基于光在粗糙表面的散射原理,采用散射光比法,能对Ra≤0.8um的粗糙表面实现快速、简便的非接触测量。改进后的轮廓仪与通用微型计算机相连,能满足在三维方向上测取粗糙度量值,并将其转化成数字量,用微机处理的要求。     

多级粗糙间隙内的两相微流动数值模拟

以带沟槽抛光垫多级粗糙间隙内的固液两相微流动为研究对象,基于计算机模拟生成多级粗糙表面,利用格子Boltzmman方法(Lattice Boltzmann method,LBM)计算微观流场,对抛光液在多级粗糙间隙内的流动过程以及固体颗粒的运动轨迹进行分析。探讨将这种新的抛光液两相微流动分析方法用于平坦化机理研究的可行性,并初步研究固体颗粒在多级粗糙间隙内的运动和碰撞过程,分析固体颗粒的运动特性。研究表明,多级粗糙表面的计算机模拟生成技术结合稀疏两相流模拟可以用来分析多级粗糙间隙内抛光液流动和固体颗粒运动轨迹。通过对抛光垫多级粗糙间隙内两相微流动的研究,有助于揭示晶片表面缺陷产生的机制,并提出减少缺陷的抛光垫微结构设计及修整方案。