共查询到20条相似文献,搜索用时 15 毫秒
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On-line phase measuring profilometry based on phase matching is proposed. While just one fixed sinusoidal fringe is projected on a measured object moving with the pipeline, deformed patterns modulated by the object moving at the same distance moment are captured synchronously by the CCD camera. The phase information of the object in those captured deformed patterns can be predicted using FTP method to assist the pixel matching so as to realize the point-to-point correspondence of the object in the captured deformed patterns. Meanwhile, the equivalent phase-shifting deformed patterns can be extracted. So the three dimensional shape of the object can be reconstructed successfully with an equal phase-shifting algorithm. Numerical simulation and experiments show feasibility and validity of the proposed method. 相似文献
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基于偏振位相调制的位相轮廓测量 总被引:1,自引:0,他引:1
本文介绍了一种用来测量三维物体面形的位相轮廓方法,它是通过将正弦光场投影到被测物面,该光场被物体表面调制后发生位相改变,利用偏振位相调制及位相检测算法计算物面的位相分布,再根据几何关系实现对物体三维形貌的测量。实验装置采用一种偏振位相调制的干涉光场投影装置对光场进行简便而精确的移相,采用CCD摄像机记录畸变光场,并用计算机处理和显示测量结果。文中给出了有关实验结果。 相似文献
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The present study proposes a new method for measuring the surface shape of an object using elliptically pattern grating projection. Based on phase measuring profilometry (PMP), elliptically pattern grating is projected on the surface of the object to measure its shape in 3D. The computing formula for solving the phase by the phase-shifting fringe method is derived, and the 3D shape formula for the altitude is reestablished. The error-contrastive analysis of the object's surface shape is re-established based on the proposed method and traditional PMP. The proposed method was shown to have a strong anti-noise ability and able to measure objects under high noise. More accurate measurement results were obtained by computer simulation and experiment to verify the feasibility of the proposed method. 相似文献
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A high-precision phase measuring profilometry (PMP) based on a stereo microscope is presented. A high-quality area modulation sinusoidal grating by a LED illumination is used to produce the high-quality sinusoidal fringes. Phase-shift technique is employed to get the phase distributions, and the 3D data could be reconstructed by the phase-height mapping algorithm easily. The accuracy depends on the field of view, which at a large magnification is below 1 μm. This setup will be promising for high accuracy measurement task. 相似文献
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The technique of phase-measuring profilometry is reviewed, whereby a sinusoidal grating structure is projected onto a diffuse three-dimensional surface, and the resulting deformed grating image is detected by a solid state array camera and processed by a microcomputer using interferometric phase measuring algorithms. The approach permits parallel acquisition and processing of large amounts of data with high accuracy and speed.Several systems are described, configured with telecentric laser light illumination or general white light diverging illumination, and capable of measurement from a single point of view or over full 360°. Each system consists of an optical projection assembly with phase-shifter, an imaging assembly with high density CCD camera and an IBM AT microcomputer with buffer and control cards.Applications to industrial inspection and medical diagnostics are presented. 相似文献
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介绍了在位相测量轮廓术中的一种相位修正及系统参数标定的新方法。对参考面(标定面)上点的位置_相位关系进行全场拟合,并根据该相互关系对参考面相位进行修正,能够非常有效地去除相位误差;提出的参数标定方法能精确得到投影系统参数的组合。实验证明了此方法具有良好的实用性和测量精度。 相似文献
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Global illumination affects shape measurement accuracy, and phase unwrapping is an important problem in phase measuring profilometry. In this paper, a micro-phase measuring profilometry is proposed to reduce the effects of global illumination. The wrapped phase error level of the proposed method is lower than that of the traditional micro-phase shifting method. First, a frequency selection rule is developed in combination with the micro-phase rule to design the frequencies of the proposed phase measuring profilometry. The frequency rule is obtained by analysing the uncertainty of the wrapped phase caused by intensity noise. Then, phase unwrapping is regarded as a congruence problem, and the closed-form robust Chinese remainder theorem algorithm is adopted to determine the correspondence. Finally, the comparative experiments are conducted on a projector-camera system. Experimental results show that the effects of global illumination can be effectively reduced with the proposed phase measuring profilometry, and the proposed frequency selection rule is valid. In addition, the performance of the robust Chinese remainder theorem in addressing the phase error is better than that of traditional Chinese remainder theorem. Furthermore, the unwrapping accuracy can nearly reach 100% if the frequency selection rule is satisfied. Otherwise, the performance degrades. 相似文献
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In Fourier transform profilometry (FTP), the zero frequency of the imaged patterns will influence the measurement range and precision. The π phase shifting technique is usually used to eliminate the zero order component, but this method requires the capture of two fringe patterns with a π phase difference between them, which will impede the real time application of the method. In this paper, a novel method is proposed, in which a composite structured light pattern is projected onto the object. The composite structured light pattern is formed by modulating two separate fringe patterns with a π phase difference along the orthogonal direction of the two distinct carrier frequencies. This method can eliminate the zero frequency by using only one fringe pattern. Experiments show that there is no decrease in the precision of this novel method compared with the traditional π phase shifting technique. 相似文献
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A modified Fourier transform profilometry (FTP) based on a fringe pattern with two frequency components is proposed, which provides a larger measuring range than that of the traditional FTP. We analyze the maximum measuring range and give an expression to describe the measurable slope of the height variation limitation of this method. The modified FTP provides us another approach to eliminate frequency overlapping. When the spectra distribution of a measured object is not spherical symmetry, we can avoid the frequency aliasing through projecting a fringe pattern with two frequency components, instead of increasing the density of the projected fringe and the resolution of a CCD camera. The theoretical analysis and primary experiments verified the method. 相似文献
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In this paper, a novel fringe demodulation method for the estimation of phase and its first-order derivative from a closed-fringe interferogram is proposed. The proposed method determines the phase derivatives in both x&y directions from fringe orientation and density. The phase derivatives are subsequently used to determine phase values using a novel simplified phase tracker. In the phase tracking model, the complexity of the cost function is reduced using predetermined derivatives so computation time required for phase tracking is reduced considerably. The proposed model is more robust while dealing with saddle points in fringes than the conventional phase tracker model. Hence it does not require any specialized scanning strategy. The proposed method is validated with simulated and experimental fringe patterns (obtained using electronic speckle pattern interferometry and optical holographic interferometry) and a comparison study is carried out with conventional regularized phase tracker. The simulation results show that the proposed method has good accuracy and requires less computation time than existing phase-tracking algorithms. The experimental results demonstrate the robustness of the proposed method against speckle noise and its practical applicability for static and dynamic applications. 相似文献
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Gamma-distorted fringe image modeling and accurate gamma correction for fast phase measuring profilometry 总被引:1,自引:0,他引:1
In fast phase-measuring profilometry, phase error caused by gamma distortion is the dominant error source. Previous phase-error compensation or gamma correction methods require the projector to be focused for best performance. However, in practice, as digital projectors are built with large apertures, they cannot project ideal focused fringe images. In this Letter, a thorough theoretical model of the gamma-distorted fringe image is derived from an optical perspective, and a highly accurate and easy to implement gamma correction method is presented to reduce the obstinate phase error. With the proposed method, high measuring accuracy can be achieved with the conventional three-step phase-shifting algorithm. The validity of the technique is verified by experiments. 相似文献