共查询到19条相似文献,搜索用时 46 毫秒
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提出了一种用于动态研究的新方法-孔径径向扫描白光散斑干涉法,介绍了两孔和直三孔径向扫描器.该方法是一种非接触式的用于动态测量的白光散斑法.分析了孔径径向扫描白光散斑干涉法的基本原理,给出了白光散斑全场滤波分析的平均光强解析式和实验结果.该方法的优点是利用散斑的调频技术能在一张白光散斑图上记录物体的连续动态变形的信息,在全场滤波分时,能将物体动态变形的信息方便地提取出来,得到清晰的全场白光散斑条纹图.直三孔径向扫描法能得到物体在x方向、y方向和45°方向上的变形信息.在实时全场滤波分析观察时,将滤波孔连续地沿径向扫描,可观察到物体连续动态变形的全过程,从而为物体的动态研究提供了一种新方法. 相似文献
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电子散斑剪切干涉术作为一种高精度全场测量技术,已被广泛应用于无损检测(NDT)、应变分析、振动检测和流场分析等领域.主要分析了电子散斑剪切干涉术在振动检测领域的应用,分析了它利用时间平均法检测振动的原理,并为实现物面振动的大面积检测进行了电子散斑剪切干涉仪光学结构的参数设计,一次可以检测大小为669 mm×502mm的矩形物面.利用计算机模拟产生随机高斯相关表面的高度分布函数及振动散斑剪切条纹图.结果表明电子散斑剪切干涉术用于振动检测. 相似文献
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将WLSI技术横向放大率M作为可变量,建立由此引起的误差关系,因此,在实际工程测量中可以充分利用成象系统景深扩大测量范围,以2m长砼梁一次成象加以验证,首次获得砼结构的全场变位分布图。 相似文献
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本文介绍了一种适用于数字散斑干涉测量流体温度场的计算机图象处理方法,主要介绍了以傅立叶变换为基础的低通滤波法在去除散斑图象噪声中的应用,从而提高了散斑干涉图的信噪比,获得了与光学干涉相似的干涉图象。将此法运用于酒精灯火焰散斑干涉图的后续处理上,取得了较好的效果,具有较高的运行效率。 相似文献
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就散射光的偏振性对剪切电子散斑干涉术中的影响进行了研究,文中给出了理论分析及实验结果,得出了消偏振效应不改变计量条纹调制度,但降低光能利用率的结论。 相似文献
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为了解决传统白光干涉测量技术中对线性位移机构的位移精度要求过高的问题,本文提出了一种全视场外差白光干涉测量技术。该技术主要通过使用存在差频的白光干涉信号作为光源来实现在大扫描步长和低扫描精度条件下相干峰位置的高精度检测。本文首先建立了白光外差干涉的数学模型,再根据数学模型提供的光强信号特性提出了整体系统设计方案,然后对测量方案的可行性进行了实验验证。最后针对多种误差对算法计算精度的影响进行了理论分析和数据对比。误差分析的结果表明:白光外差干涉测量技术提供更高的测量精度和更好的抗干扰性能,有效地降低了传统白光干涉测量对线性位移机构精度的严苛依赖,为光学自由曲面检测技术提供了更多的可选解决方案。 相似文献
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本建立了一套相移激光数字散斑干涉自动测量系统,运用一系列的图象处理方法,实现了高精度的自动测量,显地提高了数字散斑干涉计量技术的可靠性、实用性及自动化程度。该计量系统被应用于变形、振动等参数的测量中,取得了较为理想的结果。 相似文献
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N. G. Vlasov S. G. Kalenkov A. E. Shtan’ko A. V. Kritskii 《Measurement Techniques》2006,49(7):664-665
A simple method for studying the time-dependent coherence of laser radiation by speckle interferometry is proposed and tested
by experiment.
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Translated from Izmeritel’naya Tekhnika, No. 7, pp. 25–26, July, 2006. 相似文献
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Bruno Pouet Tom Chatters Sridhar Krishnaswamy 《Journal of Nondestructive Evaluation》1993,12(2):133-138
In this paper, a video-based speckle interferometric method using a continuous reference updating technique is presented. Unlike conventional ESPI techniques, this methodsynchronizes the optical interferometric detection system with the acoustic stressing of the test object, and includes continuous renewal of the reference image. It is shown that the susceptibility of the method to environmental noise caused by vibration, temperature gradients, or thermal currents is substantially lower than that of conventional techniques. The application of this technique to the detection of defects in adhesively bonded structures is demonstrated. 相似文献
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Orthognatic surgeons have a requirement for the measurement of stress distribution within the human lower jaw, in order to aid and improve surgical procedures. Validation of finite element modelling data describing mandible behaviour which has previously been attempted using holographic interferometry. Electronic speckle pattern interferometry (ESPI), a whole field non-contact optical technique has been applied to the study of a dry human mandible under load. This technique improves over previous methods by generating discrete quantitative displacement and strain components. The optical analysis of a dry mandible is described, with the results viewed in 'real time' as progressively greater forces were applied on the lower border of the chin, in the upwards (impact) direction with biting boundary conditions included in the experimental model. This has shown that the bone tissue holding the front teeth transmits the forces impacting on the chin, which are absorbed by the basal bone of the mandible. 相似文献
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Gaojianyong Wang 《Journal of Modern Optics》2013,60(13):1090-1098
Ideal low-pass filtering methods were studied in detail and adaptive elliptical ideal low-pass filters proposed for the first time. The proposed adaptive elliptical ideal low-pass filters can be used effectively for denoising of digital speckle interferograms obtained in phase-shifting digital speckle pattern interferometry. The shape of adaptive elliptical ideal low-pass filters is determined according to the spectrum distribution of interference fringes by using the adaptive method. Theoretical analysis, simulation calculation, and experimental results are presented, and are in good agreement. 相似文献
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John B. Deaton Jr. James W. Wagner Robert S. Rogowski 《Journal of Nondestructive Evaluation》1994,13(1):13-22
An electronic speckle pattern interferometer that incorporates a commercial, long-working-distance microscope is described which provides new opportunities to perform nondestructive inspection for applications in fields such as microelectronics. The long-working-distance microscrope was attached directly to the CCD camera to form a compact, portable system with a field of view that was variable over several mm in width. Alignment was greatly simplified because the skewed Michelson interferometer configuration used a speckled reference beam imaged from a diffusely reflecting reference surface that was positioned adjacent to the test object. To demonstrate the performance of the micro-ESPI instrument, fringe patterns were recorded for the quasi-static cantilever deflection of a 1 mm-wide interconnect clip from an electronics socket. 相似文献
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In spite of its obvious advantages over conventional contact and immersion techniques, laser interferometry has not yet become a practical tool in ultrasonic nondestructive evaluation since its sensitivity is insufficient in most practical applications. Part of the problem is that the maximum signal-to-noise ratio often cited in scientific publications and manufacturers' specifications cannot be maintained on ordinary diffusely reflecting surfaces. Although these surfaces reflect a fair amount (5–50%) of the incident laser light, this energy is randomly distributed among a large number of bright speckles. Unless the detector happens to see one of these bright speckles, the interferometer's signal-to-noise ratio will be much lower than the optimum. This adverse effect is almost completely eliminated by the suggested random speckle modulation technique. The conventional interferometric technique was modified to assure random occurrence of a few very bright speckles and to move the whole speckle pattern around at an appropriate speed. Random but frequent bright flashes detected from the surface of the specimen resulted. The bright periods are 0.1 ms or longer, sufficient to trigger the ultrasonic pulser and detect the transmitted signals before the flash subsides. As much as 5–10 times improvement of the optical sensitivity was achieved by this novel approach and close to maximum signal-to-noise ratio was maintained everywhere on the surface of a diffuse object. 相似文献
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In digital speckle pattern interferometry, the denoising of speckle fringe patterns is of vital importance for quantitative extraction of phase distribution. A filtering method of fast discrete curvelet transform based on weighted average thresholding technique is proposed in this paper for noise removal in speckle fringe patterns. Both computer-simulated and experimental digital speckle pattern interferometry fringe patterns are adopted to evaluate the performance of the proposed filtering method. In addition, a widely used and representative filtering method, windowed Fourier filter, is introduced for making a comparison and validation in the image processing effect, and the parameter of peak signal noise ratio is also used for assessment of denoising effect. It is shown from the filtered results that the filtering method of fast discrete curvelet transform is effecitve to remove speckle noises and simultaneously preserve fringe structure information. 相似文献
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White-light interferometry (WLI) on rough surfaces is based on interference from individual speckles. The measurement uncertainty of WLI is limited by a random shift of these individual interference patterns. The statistical error in each measurement point depends on the brightness of the corresponding speckle: a dark speckle yields a larger error than a bright speckle. In this paper, a novel method is presented to reduce the measurement uncertainty significantly: by sequentially switching the direction of the illumination, the camera sees several independent speckle patterns in sequence. From each pattern, the brightest speckles are selected to eventually calculate an accurate height map. This height map displays no outliers, and the measured surface roughness is close to the stylus measurements. 相似文献