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Xing-zhi Gong 《Optics Communications》2010,283(20):3989-3993
This paper, for the first time, proposed a new sensitivity separation (SS) method for measuring thicknesses of multilayer thin-film stack with high efficiency and accuracy. Through the analysis of the relationship between the film parameters and the mean misfit error (MSE), a parameter called sensitivity is defined. With this parameter, an estimated rational thickness is assigned to a layer with lower sensitivity first, and then the layer thickness with high sensitivity is further obtained by optimization techniques. This method will greatly reduce the searching range and increase the iterating efficiency. It is a pretreatment method and it can be used with other optimization methods. Both theory and simulation results are provided in detail. The uncertainty problems are discussed and examples are given to verify the effectiveness of this method. 相似文献
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This paper reports an investigation into the use of Acoustic Emission (AE) for monitoring gear teeth defects under varying lubrication regimes in helical gears. The investigation used a back-to-back gearbox test-rig with oil-bath lubrication. Variation in oil film thickness was achieved by decreasing the gear metal temperature with nitrogen gas whilst the gears were in operation. Results demonstrate a clear relationship between AE activity, operating temperature and specific film thickness. In addition, results show that there are lubricating conditions that may prevent AE from identifying the presence of gear defects. 相似文献
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This study develops a non-destructive measurement system for determining the thickness and refractive indices of birefringent optical wave plates. Compared to previous methods presented in the literature, the proposed metrology system provides the ability to measure the thickness of the birefringent optical plate in high-precision. The results show that for a commercially available birefringent optical wave plate with refractive indices of ne=1.5518, n0=1.5427 and a thickness of 452.1428 μm, the experimentally determined value for the error in the wave plate thickness measurement is just 0.046 μm. The measurement resolution of the proposed system exceeds that of the interferometer hardware itself. The proposed method provides a simple yet highly accurate means of measuring the principal optical parameters of birefringent glass wave plates. 相似文献
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研究水表薄油膜厚度与其反射率光谱之间的变化规律,对于分析海洋油膜污染和油气勘探的遥感探测机理具有十分重要的意义。建立了水面薄油膜厚度的生物光学模型,并介绍了单波段和双波段比值简化算法反演薄油膜厚度信息的方法。通过对原油样品进行油膜厚度定量反演,研究了遥感反射率随水表油膜厚度的变化规律。研究发现,可见光到近红外波段(450~800nm)反射率对油膜厚度变化最为敏感,有很高的负相关关系,并且随着油膜厚度的增加呈负指数形态下降。对于浅水环境较混浊的水体,ETM1/ETM3双波段比值模型可以较好的消除线性天空散射光的影响,克服单波段反演模型在不同水质背景下反演效果不稳定的特点,其反演结果的复相关系数R2可以达到0.98,是水表薄油膜厚度遥感探测的较好波段选择。 相似文献
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玻璃基片上SiO_2膜层厚度的测量方法 总被引:1,自引:0,他引:1
钠钙玻璃基片在液晶显示器件(LCD) 等制造业中得到了广泛的应用。为防止基片中的碱金属离子扩散到器件的工作介质中,进而影响其化学稳定性和使用寿命,一般要在基片表面镀上一定厚度的SiO2 膜层,以便起到阻挡层的作用。基于P 蚀刻剂对SiO2 膜层和基片有显著不同的蚀刻速度,提出了一种测量玻璃基片上的SiO2 膜层厚度的方法,即:利用表面轮廓仪,在测量三个不同的蚀刻数据后,计算出SiO2 膜层的厚度。以用射频溅射法制备的SiO2 膜层为样品进行了测量,具体的实验数据证实了该方法的可靠性和有效性 相似文献
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This paper indicates a simulation analysis for estimating the aluminum (Al) thin film thickness measurements by using the low energy electron beam. In order to calculate the Al thickness estimation, the energy of the incident electron beams was varied from 10 to 30 keV, while the thickness of the Al film was varied between 6 and 14 μm. From the simulation results it was found that electron transmittance fraction in 14 μm sample is about nine orders of magnitude more than 6 μm sample at the same incident electron beam energy. Simulation results show that maximum transmitted electrons versus Al layer thickness has a parabolic relation and by using the obtained equation, it is possible to estimate unknown thickness of the thin film Al layer. All calculations here were done by CASINO numerical simulation package. 相似文献
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针对柔性复合薄膜成形试验中极限应变难以测量的问题,提出一种基于双目立体视觉结合数字图像相关法的测量方法。首先对于薄膜材料成形过程中产生大变形或裂纹时图像难以匹配的问题,根据系列图像相邻状态变形的连续性,提出了一种图像匹配基准自适应更新的弱相关分步匹配方法;然后根据薄膜材料表面应变分布不同于钢制件的特性,提出了一种构建应变场截线来拟合薄膜材料的极限应变曲线的方法。专门组建视觉测定的软、硬件系统,通过Q235钢试件进行极限应变曲线测量并与坐标网格方法进行对比,材料极限应变精度能够提高0.02%,证明了本文方法的可行性和精确性。用7组PET/Nylon/Al foil/PP材料制备成的柔性复合薄膜试件进行实测,此方法及系统成功地完成了柔性复合薄膜材料的成形极限曲线测定。对比实验和实际测试证明,本文方法能够快速、准确地测量柔性复合薄膜材料在整个成形过程中的表面应变分布,与传统的坐标网格方法相比具有明显的优势,为测定薄膜材料的成形极限应变曲线提供了一种高可靠性、高精度的手段。 相似文献
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A two-beam laser triangulation method has been proposed to measure the position of a moving object. The method uses two parallel laser beams to judge the moving direction of an object, allowing us to track it and measure its positions. An uncertainty of 0.2 mm for a measurement range of 50 mm has been obtained. This tracking measurement capability is useful in the calibration of the position of a moving robot arm. 相似文献
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Methods of measuring ultrasonic wave velocity in an elastic sample require data on the thickness of the sample and/or the distances between the transducers and the sample. The uncertainty of the ultrasonic wave velocity measurements generally depends on that of the data available. Conversely, to determine the thickness of a material, it is necessary to have a priori information about the wave velocity. This problem is particularly hard to solve when measuring the parameters of biological specimens such as bones having a greater acoustical impedance contrast (typically 3-5 MRayl) than that of the surrounding soft tissues (typically 1.5 MRayl). Measurements of this kind cannot easily be performed. But obtaining the thickness of a bone structure and/or the ultrasonic wave velocity is a important problem, for example, in biomechanical field for the calculation of elastic modulus, or in acoustical imaging field to parameterize the images, and to reference the grey or color level set to a physical parameter.The aim of the present study was to develop a method of simultaneously and independently determining the velocity of an ultrasonic wave in an elastic sample and the wave path across the thickness of this sample, using only one acquisition in pure transmission mode. The new method, which we have called the “Wavelet-Based Processing” method, is based on the wavelet decomposition of the signals and on a suitable transmitted incident wave correlated with the experimental device, and the mathematical properties such as orthonormality, of which lend themselves well to the time-scale approach. By following an adapted algorithm, ultrasonic wave velocities in parallelepipedic plates of elastic manufactured material and the apparent thicknesses were both measured using a water tank, a mechanical device and a matched pair of 1 MHz ultrasonic focused transducers having a diameter of 3 mm, a focal length of 150 mm and beam width of 2 × 2 mm at the focus (mean temperature 22°). The results were compared with those obtained with a conventional Pulse-mode method and with the control values, to check their validity. Measurements performed on bovine and human dry cortical bone samples are also presented to assess the limitations of the method when it is applied to elastic biological samples, including those of an equal-wavelength size (≈1.5 mm). The thicknesses and the ultrasonic wave velocities were then measured in this kind of (quasi-) parallelepipedic elastic materials with an mean estimated error ranged from 1% to 3.5% compared to the referenced values. 相似文献
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《Journal of Physics and Chemistry of Solids》2014,75(4):500-504
This paper investigates the dependence of surface undulation on a film thickness considerably greater than the critical value of a thin film system. It considers that surface tension and residual stress are the main cause of surface undulation. The study found that there is a critical undulation wavelength that minimizes the free energy of a thin film system, that this critical wavelength depends on the film thickness, and the effect of undulation amplitude is insignificant. The research also found that the surface undulation has a negligible influence on the residual stresses in the thin film system. 相似文献
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High speed laser patterning of indium tin oxide thin films on glass is part of the production method used to produce transparent conductive electrodes for plasma display panels. Such a design consists of rows of repeating electrode structures which cover the active area of the display. Whilst the patterning process for such electrode structures exceeds the industrial acceptance criteria there are certain features that are yet to be fully understood. The visible line that occurs in-between two adjacent laser processed areas, commonly known as a stitch line, is one such feature. Previously published research claimed that the stitch line was caused by incomplete removal of the thin film however experimental results presented within this paper demonstrate that this cannot be the case and show that the stitch line is formed by redeposition of the plume of ablated material within the area of overlap with the previous pulse, and that heating of the sample by the second pulse plays a key role in stitch line formation. 相似文献
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用波长1.06μm、半高宽10ns的脉冲Nd:YAG激光辐照铜膜镜面,在激光辐照区,用光学显微镜观察到有规律的环形波纹状损伤图案,波纹平均周期约几十μm。通过对光路系统分析,认为样品前的小孔光阑对激光产生了菲涅尔衍射,使得在样品表面光强分布变成周期性环状分布。在极短的相互作用时间内,热扩散很小,损伤图案依赖于光强分布。并依据实验参数,用柯林斯公式对样品表面的光强分布进行了计算,所得光强分布的周期与损伤波纹的周期基本一致。 相似文献
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激光法红外热像镜组中心偏测量与调校研究 总被引:9,自引:0,他引:9
论述了多镜片成像光学镜组中心偏的理论表征 ,以及自准反射旋转法测量中心偏的原理。设计了用于红外光学镜组的中心偏检测系统。系统包括用于 8~ 14 μm红外光学系统中心偏测量的CO2 激光 ;可调焦望远镜 ;采用TGS热释电热像仪与计算机配合的数据读出及处理系统 ;径向跳动≤ 1μm ,轴向晃动≤ 1″的高精密基准轴工作台。系统测量中心偏精度为 :角度≤ 2″ ,线度≤ 0 .0 2mm。给出了中心偏数据处理程序。系统也可用于在线装校 ,更换光源 (用He Ne激光代替CO2 激光 )系统可用于 3~ 5 μm红外光学系统的测量。进一步改进并利用激光的相干特性 ,系统可实现中心偏测量精度≤ 1μm。 相似文献
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Ik-Bu Sohn Young-Chul Noh Sung-Chul Choi Do-Kyeong Ko Jongmin Lee Young-Jin Choi 《Applied Surface Science》2008,254(16):4919-4924
A polypropylene (PP) film was ablated using a femtosecond laser with a center wavelength of 785 nm, a pulse width of 184 fs and a repetition rate of 1 kHz. Increments of both the pulse energy and the shot number of pulses lead to co-occurrence of photochemical and thermal effect, demonstrated by the spatial expansion of rim on the surface of PP. The shapes of the laser-ablated PP films were imaged by a scanning electron microscope (SEM) and measured by a 3D optical measurement system (NanoFocus). And, the gas and water vapor transmission rate, mechanical properties of PP film micropatterned by fs laser pulses was characterized. Our results demonstrate that a femtosecond pulsed laser is an efficient tool for breathable packaging films in modifying the flow of air and gas, where the micropatterns are specifically tailored in size, location and number of which is easily controlled by laser processing conditions. 相似文献