随着现代社会经济的迅猛发展,对精密工件的表面粗糙度测量技术也提出了更高的要求.表面粗糙度是衡量加工工件表面质量的重要标志之一,所以准确测量表面粗糙度至关重要.激光测量技术具有快速、非接触、无损特点,因此显得倍受青睐.随着人们对相干激光产生的散斑的认识深入,激光散斑技术作为一种统计测量技术越来越多的人把散斑技术应用到测量表面粗糙度领域.本文介绍了基于灰度共生矩阵和自相关函数的对工件表面粗糙度进行研究的两种激光散斑测量技术.

为了得到效果更佳的朗奇图像,提出了一种运用小波分析来处理大口径非球面镜图像的方法。选取半通光口径为300mm的大口径非球面进行了测量,首先利用Matlab对原始图像进行一层小波变换、二层小波变换,再对初步优化后的图像进行恢复处理,即小波去噪。优化后的图像经过分析计算,将其波像差的峰谷值、方均根值与Zygo干涉仪进行了对比,并讨论了测量结果。实验表明:小波分析处理朗奇图像的方法是有效的,优化后的朗奇图像较未处理图像边缘更为清晰、光滑,实验数据更接近于Zygo干涉仪的结果。

随着现代社会经济的迅猛发展,对精密工件的表面粗糙度测量技术也提出了更高的要求。表面粗糙度是衡量加工工件表面质量的重要标志之一,所以准确测量表面粗糙度至关重要。激光测量技术具有快速、非接触、无损特点,因此显得倍受青睐。随着人们对相干激光产生的散斑的认识深入,激光散斑技术作为一种统计测量技术越来越多的人把散斑技术应用到测量表面粗糙度领域。本文介绍了基于灰度共生矩阵和自相关函数的对工件表面粗糙度进行研究的两种激光散斑测量技术。

A measurement method of the large-aperture aspheric surfaces with the ronchi wonderful legal quantity the new technology was proposed. The large-aperture aspheric surfaces mirror's processing surface was taken as the example of study. The large-aperture aspheric surfaces examination system was designed. This system was composed by the CCD camera, the He-Ne laser, the ronchi grating, the microcomputer. By using the large aperture aspheric surfaces examination system, the face shape was measured, when the apex radius of curvature was 638. 69 mm, the half light culiker was 315 mm. The optical element standard deviation and the valley value measurement were presented. The results show that based on the geometry priciple of the Ronchi, the method by using the CCD photograpg system to measure the large aperture aspheric surface has the advantage of high precision.

采用激光散斑的实验方法,拍摄了连续多幅不同加工工艺、不同表面粗糙度标准样块的散斑图像.利用基于灰度共生矩阵的纹理分析方法对图像的4个特征参数--角二阶矩、惯性矩、相关性和熵进行了计算、统计与分析.研究表明,连续多幅激光散斑图像的各种参数取值会有波动,但整体趋于平稳:验证了表面粗糙度和特征参数之间存在着规律性的曲线关系;进一步消除了外界干扰和装置随时间的动态不确定性,使得实验结果更可靠,同时扩大了表面粗糙度和4个特征参量之间的关系数据库,验证了激光散斑的方法对测量表面粗糙度具有较高的可信度.

为了实现对大口径非球面在细磨和初抛光的加工过程中出现的较大误差的测量,提出了将龙基(Ronchi)光栅、图像采集以及数字图像处理技术相结合的一种较大误差的定量测试方法.介绍了该方法的基本原理、建立了数学模型、编制了相应的数字处理软件.利用该方法对一直径为140 mm,F数为2的凹形抛物面镜进行了测试实验.通过该测试方法以及数据处理软件,得到了准确的非球面面形分布图,检测结果与经典的干涉仪检测结果想比较,二者是相一致的.将为大口径非球面精磨和初抛光阶段提供一种有效、可靠的定量检测方法.

The non-planar surface roughness formed in different processing is studied based on autocorrelation function.The relationships between autocorrelation function,measuring parameter and image texture are discussed.The experimental setup is built.The laser speckle is processed by image processing software.The relation curves of autocorrelation function and surface roughness are obtained.

The Ronchi grating is applied to measure the large-aperture aspheric surfaces in a quantitative way on the basis of self-made software which includes Ronchi null grating design, collection of Ronchi graph, and data processing. The measured concave parabolic mirror has a diameter of 630 mm and an F number of 1.34. The measurement result is approximately the same as that of the ZYGO interferometer. This analysis software and test method establish a good foundation for the quantitative measurement of the big error about the large-aperture aspheric surfaces of the next generation telescope.

Ronchi grating test has been used widely to test optical surfaces in a qualitative way since it was contrived, while rarely to test the parabolic surface in a quantitative way. This paper discusses the application of Ronchi grating test to optical aspheric surfaces in a quantitative way on the base of self-made software which includes Ronchi null grating design, collection of Ronchi graph, data procession and so on. The whole system has been used to test a concave parabolic mirror with diameter 140mm and F number 2, and the result is approximately the same as that of the outcome of interferometer. The analysis software and test method establish a good foundation for the coming of quantitative measurement of big error of large-aperture aspheric surfaces.

Ray tracing and the third-order aberration theory on design of Ronchi grating are introduced.The Ronchi gratings are designed with MATLAB and the flow chart of computer plotting is given.Input parameters include different paraxial curvature radius of large paraboloid mirror radius,different distance between spot source and Ronchi grating distance and so on.The Ronchi gratings of different odd number and even number are obtained.The result shows that the method can get the lateral aberration accurately and quickly and provide a new method for the design of Ronchi grating.The Ronchi gratings designed have the advantages of high quality,clean edges and the smooth fringes.

The formation and statistical characteristic of laser speckle are introduced. The speckle images of samples with different processing and different surface roughness are taken. Based on the gray level co-occurrence matrix, moment of inertia, entropy, angle second moment of laser speckle, the texture of images is analyzed. The relation curves of the four parameters and surface roughness are drawn. The experimental results and the data of the object with unknown surface roughness are compared, and the surface roughness of the object are accurately estimated.

The laser speckle patterns taken from grinded work-piece surface of a glass plane is processed to obtain the data results related to surface roughness using a visual user interface which has been developed with an experimental setup mainly consisting of He-Ne laser and CCD. The functions of processing the speckle images with the user interface are presented such as smooth the images by Gauss filter before other processions, and make the binary images by the threshold got with OSTU and present its histogram. We give the fitting curve of laser speckles' probability density distribution and their parameters, and Calculate their texture characteristic parameters such as angle-second moment, inertia (contrast), correlation and entropy value. The user interface of computer is developed using GUIDE from MATALB. We also present to compare the experimental results produced from laser speckle patterns at different detective angles and distance with the theory. The studies are useful to processing data for the measurement of surface roughness and profile of the work-piece using laser speckle method.

A new quick processing method to obtain the statistical properties of the weak laser speckle in free-space diffraction field whose speckle contrast V is less than 1 has been presented in this paper. During the process of experimental work, the conventional hypothesis of the laser speckle statistical regularity of keeping roundness was used. Based on the hypothesis, many images of laser speckle in different detection angles by a CCD sensor on the surface of samples coated with thermal sprayed with ZrO28Y2O3 have been processed. The density distribution of probability and the contrast of speckles were obtained. Even though the processing experimental data is gray-matrix but the intensity-matrix, the results are the same. The rationality of the process and the density distribution of probability are discussed in this paper. The experimental results accord well with the theoretical analysis and indicate that the method is feasible. This method makes the measurement of the surface roughness by laser speckle more convenient.

The relation between the detective angles and the parameters of laser speckle have been presented. The experiments and calculations indicate the parameters with CCD images such as speckle contrast, entropy, energy and average value have different results due to the different forms of the detective angles. The analysis with maximal histogram can obtain a result that the average diameter of spots dotted in laser speckle pattern tends to be smaller with the angle increasing and the spots’ distribution appear to be more uniform.It is shown the results are useful to analyze the images capturing by CCD in some measurements.

对热喷涂涂层NiCrAlY粗糙表面激光散斑场的一级统计特性进行了理论和实验研究.用数字方法进行分析,采用Mathcad读取灰度矩阵模拟基元强度分布.实验数据显示理论与实验结果有很好的吻合,表明此方法是合理的,在实践中是可行的.

提出了利用激光非接触点扫描测量涂层厚度的方法.研究了激光照射新型材料ZrO28Y2O3涂层粗糙表面上光点的高斯分布,并利用扫描电子显微镜得到了涂层粗糙表面的显微精细结构.采用激光-面阵CCD传感器-计算机数字图像处理技术测量涂层厚度.实验结果表明:所提出的测量方法是可行的,测量涂层厚度的重复性误差在±5 μm范围内.

The light spot images on the coating rough surface with the plasma-thermal sprayed coating materials Z(r)O(2)8Y(2)O(3) and NiCrAlY when the laser beam (visible, wavelength is 632.8nm, power is 2mw) with different diameter shined on it have been studied and its experimental demonstration has also been presented in this paper. The Charge Coupled Device(CCD) camera is applied to detect the light spot image field distribution, and three-dimensional (3D) distribution of the light spot images have been obtained by computer. Above experiment results give us some basis knowledge to measure the coating thickness in the next step, which shows the physical behavior of the light spot. In addition, the different profiles of Gauss laser spot image on the rough surface for ZrO(2)8Y(2)O(3) and NiCrAlY coating have been analyzed.

The light spot images on the coating rough surface with the plasma-thermal sprayed coating materials ZrO28Y2O3 and NiCrAlY when the laser beam (visible, wavelength is 632.8 nm, power is 2 mw) with different diameter shined on it have been studied and its experimental demonstration has also been presented in this paper. The Charge Coupled Device camera is applied to detect the light spot image field distribution, and 3D distribution of the light spot images have been obtained by computer. Above experiment results give us some basis knowledge to measure the coating thickness in the next step, which shows the physical behavior of the light spot. In addition, the different profiles of Gauss laser spot image on the rough surface for ZrO28Y2O3 and NiCrAlY coating have been analyzed.

针对两种等离子热喷涂涂层ZrO28Y2O3和NiCrAlY (金属基底)的不同粗糙表面的实验样品进行了激光空间散射场实验研究.采用了He-Ne激光光源(波长λ=633.0 nm;激光功率P=2 mW).将激光束倾斜一定角度直接照射到实验样品上,在不同散射角和不同散射空间距离位置上用面阵CCD传感器探测空间散射光场分布.实验结果表明:不同散射方向的空间散射光场分布是不一样的,从而为进一步利用光学方法测量热喷涂涂层工业参数,诸如涂层厚度,表面形态等提供了一定的实验依据.

A new method of reprography and detection employing scan electron microscope (SEM) for the non-destructive testing the micro-cracks with width about 1 μm on the inner surface of the pinhole has been presented in this paper. The results show that the new method is a feasible approach to test the micro-cracks of the inner surface of the pinhole with sub-millimeter aperture.