共查询到20条相似文献,搜索用时 15 毫秒
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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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Abstract In this paper we describe a digital double-pulsed holographic system. Two separate holograms of an object under test are recorded within a few microseconds using a charge-coupled device camera and stored in a frame grabber. The holograms are digitally reconstructed using a computer, by simulation of the Fresnel diffraction of the hologram illuminated by the reference wave. The phases of the two reconstructed wave fields are calculated from the complex amplitude and the deformation is obtained from the phase difference. Experimental results are presented. 相似文献
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Abstract A novel technique for phase detection using three-step spatial phase-shifting interferometry is presented. The presented technique overcomes and studies the two main problems presented in the commonly used three-step phase-stepping technique. These problems deal with the leak of carrier frequency in the detected phase and the optimal carrier frequency to obtain the highest phase noise robustness. 相似文献
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Th. Kreis J. Müller C. von Kopylow W. Jüptner 《Materialwissenschaft und Werkstofftechnik》2006,37(1):76-80
Digital holographic interferometry is a coherent‐optical method for noncontacting measurement of full field deformations in the micrometer‐range. While deformations in the range of the wavelength of the used laser‐light are determined by comparison of the phases of the wave fields reconstructed from the recorded holograms, for larger deformations the form of the object surface has to be measured by a holographic interferometric contouring method, followed by numerical comparison of two such measured contours. Here we present such methods for determining the distortions of hot moving components leading to a concept for an in‐process distortion measurement enabling early interaction with e. g. the quenching process to control the resulting distortion. 相似文献
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Gaetano Restivo Gabriel A. Isaicu Gary L. Cloud 《Journal of Nondestructive Evaluation》2008,27(4):135-142
The paper demonstrates a low-cost approach based on speckle interferometry (SI) for the nondestructive inspection (NDI) of
metallic and composite plates. Speckle interferometry, and optical methods in general, provide a clear picture of the inspected
area, where anomalies are immediately detected, and can yield results in real-time. They are often expensive though, and sensitive
to environmental disturbances. Relevant literature in the area of nondestructive inspection is reviewed aiming to find the
most suitable configuration for a low-cost system. The chosen setup is a simplified digital speckle interferometer (SDSI),
which includes only three main components: a He-Ne laser, a standard CCD camera and a light-scattering window. This simplified
configuration removes the requirement of mechanical stability by using a configuration close to the common-path interferometer.
The SDSI device is here tested for the detection of thinning defects in Aluminum plates, and delamination in composite plates.
Among the various stressing techniques, localized heating was found to be the simplest, yet most effective approach. Results
show that the presence of defects creates unique features in the live correlation fringes, from which it is possible to identify
the location and size of the defects. It is in conclusion demonstrated that the SDSI device is a valuable tool for fast, low-cost,
and non-contact nondestructive inspection. 相似文献
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Three-dimensional Displacement Analysis by Windowed Phase-shifting Digital Holographic Interferometry 总被引:1,自引:0,他引:1
Abstract: Phase-shifting digital holography is a new method for measuring the displacement distribution on the surface of an object. The authors previously proposed a windowed phase-shifting digital holographic interferometry (windowed PSDHI). This method provides accurate displacement distributions by decreasing the effect of speckle patterns. In this study, the method is extended to analyse three-dimensional displacement components in a microscope. Three object laser beams in the optical system are used. Four phase-shifted holograms are recorded for each object laser beam. The complex amplitude of each reconstructed light at the object is calculated by the Fresnel diffraction integral of the complex amplitude of the hologram. The reconstructed distance is obtained at the point with the maximum of the standard deviation of the intensities of the object reconstructed with changing the reconstruction distance. The three phase-difference values between before and after deformation provide the three-dimensional displacement components. Theoretical treatment and experimental results of three-dimensional displacement measurement using this method are shown. 相似文献
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P. Ziekman 《Materialwissenschaft und Werkstofftechnik》1974,5(3):124-128
An industrial application of the oblique illumination technique used for holographic interferometric comparison of non-optical surfaces is presented. A holographic interferometer for testing cylindrical and taper rollers is described. Experimental results are given, while it is discussed how to measure very small form deviations in spite of a decreased sensitivity of the interferometer due to the oblique illumination technique. 相似文献
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激光数字波面干涉仪傅里叶变换移相干涉术 总被引:4,自引:0,他引:4
讨论了一种新的干涉图处理方法,能实时快速准确地提取干涉图信息,直接测量波面的位相分布,获得较高的位相分辨率和空间分辨率,使光学波面的检测精度达到λ/100以上,并且实现了波面的的实时显示。 相似文献
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21世纪的今天数字技术已广泛应用于各行各业,给社会和人们的生活带来了巨大的变化。在电影领域里,数字技术从局部应用到系统应用、从试验到实践,目前电影正从传统的胶片方式向数字方式全面的过渡。这给电影带来了前所未有的变化和挑战,同时也带来难得的发展机遇。一、数字技术给电影带来的变化电影数字化是电影诞生百年以来最大的一次创新和变革。它使电影从艺术创作、拍摄制作和发行放映、市场运营到管理模式都发生了深刻的变化。中国的电影数字化应用始于90年代中期电影数字立体声的制作与放映。10年来特别是近几年在总局、电影局数字化发… 相似文献
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工件在检定过程中受到多种影响因素,其中仪器的影响占主要因素,为了提高测量精度,采用分离技术以消除仪器部分误差尤为重要。分离技术可用电算法和实用法,本文介绍其实用法。 相似文献
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T.W. Ng 《Journal of Modern Optics》2013,60(10):2109-2118
Abstract An object step-loading method has been recently reported to overcome the problems of phase unwrapping and decorrelation in digital speckle shearing interferometry. In this paper, a carrier modulation procedure is incorporated into the object step-loading method in order to improve the phase derivation accuracy. An added advantage with this approach is that the direction of deformation is also revealed. 相似文献
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This article is devoted to the evaluation of refined theories for static response analysis of piezoelectric plate. The Carrera Unified Formulation (CUF) is employed to generate the refined plate models. The CUF allows the hierarchical implementation of refined models based on any-order expressions of the unknown variables. Equivalent single layer (ESL) and layerwise (LW) approaches are used to generate the refined models. The governing equations are obtained considering Navier-type, closed-form solutions. The axiomatic/asymptotic technique is employed in order to evaluate the relevance of each model term. This technique computes the relevance of a model term by measuring the error introduced with its deactivation with respect to a reference solution. The axiomatic/asymptotic technique is applied considering the sensor and actuator configurations for piezoelectric plates. Moreover, the analyses are performed taking into account the influence of the length-to-thickness ratio (a/h) and the use of isotropic or orthotropic materials. “Best” models are proposed and the stress/displacement components and electric potential distributions are evaluated by means of these reduced models. 相似文献
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G. Bovesecchi P. Coppa S. Corasaniti M. Potenza 《International Journal of Thermophysics》2018,39(7):82
The paper presents an analysis of the experimental parameters involved in application of the dual-probe heat pulse technique, followed by a critical review of methods for processing thermal response data (e.g., maximum detection and nonlinear least square regression) and the consequent obtainable uncertainty. Glycerol was selected as testing liquid, and its thermal diffusivity was evaluated over the temperature range from ??20 °C to 60 °C. In addition, Monte Carlo simulation was used to assess the uncertainty propagation for maximum detection. It was concluded that maximum detection approach to process thermal response data gives the closest results to the reference data inasmuch nonlinear regression results are affected by major uncertainties due to partial correlation between the evaluated parameters. Besides, the interpolation of temperature data with a polynomial to find the maximum leads to a systematic difference between measured and reference data, as put into evidence by the Monte Carlo simulations; through its correction, this systematic error can be reduced to a negligible value, about 0.8 %. 相似文献
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Abstract: In this paper, the displacement field induced by the split‐sleeve cold expansion of holes was measured using both digital image correlation (DIC) and digital speckle pattern interferometry (DSPI) techniques. Thus, the experimental results, which were evaluated on the inlet surface of a 6082‐T6 aluminium plate, were compared with those from theoretical prediction. DIC provided accurate measurements up to the elastic–plastic boundary, whereas the DSPI technique highlighted the changes of displacement in the elastic domain. Prediction of the displacement based on the existing analytical model agreed with the experimental results achieved with both techniques. Possible explanations for the differences are discussed. 相似文献