共查询到19条相似文献,搜索用时 78 毫秒
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提出一种有效的单帧闭合条纹解调方法,该方法采用傅里叶变换、带通滤波器和傅里叶逆变换估得初始相位,然后通过图像分割、相位符号校正和Zernike多项式拟合得到高准确度相位分布.用图像分割和相位符号校正解决了相位符号不确定性,用Zernike多项式拟合抑制了分割线附近的局部相位误差.数值分析了残余相位误差与干涉图参量(如倾斜量、离家量和随机噪音)之间的定性关系,结果表明:该方法所得相位与ZYGO移相干涉仪测试结果吻合较好,残余相位误差小于参考值的1/10,验证了该方法的有效性. 相似文献
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针对大口径光学元件干涉测试过程中,测试装置和干涉腔长较大,气流扰动和环境振动对移相测试过程产生影响等问题,采用一种基于二维傅里叶变换的单帧干涉图处理方法,只需要对一幅空间载频干涉条纹图进行处理即可获得待测相位,具有抗振测试的优点。对该方法的基本原理和算法过程进行分析,并对近红外大口径移相平面干涉仪中600 mm口径的光学平晶进行了面形测试。实验结果表明:采用该方法所得波面峰谷值(PV)为0.112,波面均方根值(RMS)为0.014,与移相算法所得波面数据相比,波面峰谷值偏差不到(1/500);波面均方根值(RMS) 偏差几乎为零。 相似文献
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提出了一种基于光强迭代的单幅干涉图相位提取方法,实现了对单幅干涉条纹图的高精度相位提取。首先通过对原始干涉图进行预处理得到初始相位;将初始相位引入到干涉条纹图的强度表达式中,利用最小二乘法初步得到背景光和调制光;再将初步估计的背景光和调制光代入最初干涉图的强度表达式中以求解待测相位,比较得到的待测相位和初始相位,若不满足迭代精度要求,则重复上述相位求解过程并实现迭代,若求解的相位与初始相位的均方根差值满足收敛条件,则停止迭代。进行仿真和实验研究,得到的Φ100 mm口径平面元件的测量提取结果与实际相位一致。结果表明,该方法在具有较高检测精度的同时能够有效地保证算法的稳定性。 相似文献
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静态傅里叶变换光谱仪的机理及干涉条纹的校正 总被引:1,自引:0,他引:1
针对高速、瞬时光谱测量要求光谱仪的结构简单、装备方便、实时性强的特点,文章介绍了一种静态傅里叶变换光谱仪,并对其原理进行了推导与剖析。针对其调整中出现的干涉条纹的倾斜校正问题,进行了详细的理论分析和干涉条纹模型的数学推导,得出倾斜镜旋转参数和光学元件最小通光口径之间的数学关系,以及倾斜镜旋转参数和干涉条纹旋转参数之间的数学关系。通过利用Matlab7.0数学工具,对所总结推导的干涉条纹模型进行模拟,对所得的各种参数之间的数学关系进行验证。分析结果表明据此数学关系所求得的β角校正精度达到1.4%,是一种有效可行的校正方法。 相似文献
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在快速傅里叶变换(FFT)方法处理单幅干涉图原理的基础上,提出一种基于样本块匹配的干涉图延拓方法,利用干涉图像的可信度和等照度线特征,来确定待填充块的优先权,然后在干涉图的已知区域寻找与待填充块最相似的样本块来进行填充。充分利用了干涉图的条纹特征,结合梯度变化方向有效地合成纹理信息,具有很好的延拓效果。最后将该干涉图延拓方法与傅里叶变换,合适的滤波函数和相位解包方法结合起来形成整套单幅干涉图处理方法。采用该单幅干涉图处理方法获得的波面峰谷值与Zygo移相干涉仪得到的平均相差不到λ/100,并且两种方法获得的波面均方根值平均相差不到λ/200。 相似文献
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Accurate carrier-removal technique based on zero padding in Fourier transform method for carrier interferogram analysis 总被引:1,自引:0,他引:1
Based on interferogram zero padding and fast Fourier transform (FFT) methods, an effective, straightforward and stable carrier-removal approach in Fourier transform (FT) based method for carrier interferogram analysis is proposed. The spatial carrier interferogram is firstly extrapolated by zero padding method, and the carrier-frequency values within a small fraction of an integral (or a pixel) are estimated from the extrapolation interferogram with FFT method. Then the carrier-phase component is removed by subtracting a pure carrier-frequency phase constructed by the estimated carrier-frequencies in the spatial domain. Numerical simulations and experiments are given to demonstrate the performance of the proposed method and the results show that the proposed method is effective and stable for suppressing the carrier-removal error in the FT method for carrier interferogram analysis. 相似文献
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Phase unwrapping is a task common to many applications like interferometry imaging, medical magnetic resonance imaging, solid-state physics, etc. Fourier transform profilometry (FTP) values the height distribution of object, elaborating the interference between a plane reference grating and a deformed object grating. Since the height information is extracted from the phase of a complex function, the phase unwrapping is a critical step of the process. Several unwrapping algorithms are proposed in literature, but applied to measurement technologies different from FTP. The purpose of this paper is to define the performances of eight different unwrapping algorithms applied to FTP optical scan method and to define the best one. The algorithms chosen are: Goldstein's algorithm, quality guided path following method, Mask cut method, Flynn's method, multi-grid method, weighted multi-grid method, preconditioned conjugate gradient method and minimum Lp-norm method. The methods were tested on real images acquired by a FTP scanner developed and calibrated for these experiments. The objects used vary from simple geometries, like planes and cylinders, to complex shapes of common use objects. Algorithms were qualified considering the phase unwrapping errors, execution time and accuracy of the shape of objects obtained from the scan method in comparison with real ones. The results show that quality guided algorithm best fits in FTP application. 相似文献
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Sanjit K. Debnath Mahendra P. Kothiyal Seung-Woo Kim 《Optics and Lasers in Engineering》2009,47(11):1125-1130
Spectral phase in a white-light interferogram contains information about the absolute optical path difference (OPD) in the interferometer. Evaluation of spectral phase is therefore important in applications such as profilometry with white light. In spectrally resolved white-light interferometry (SRWLI) the white-light interferogram is spectrally decomposed by a spectrometer in order to determine this phase. Several single-frame techniques in SRWLI have been proposed for the evaluation of the phase including Fourier transform, Hilbert transform, spatial phase shifting, windowed Fourier transform and wavelet transform. In this paper we present a comparative study of these techniques in this application in relation to the temporal phase-shifting technique which is a multi- frame method. Further, we also propose a modified method to remove the influence of source spectrum modulation in Hilbert transform procedure. 相似文献
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This paper proposes a novel method to obtain frequency modulation (FM) signals from a single fringe pattern for phase retrieval. First, a 1D discrete Meyer wavelet is employed to decompose the pattern image signal row by row and the soft-thresholding approach is applied to remove noise. The low frequency coefficients of the wavelet decomposition are then set to 0, and the signal is reconstructed. Moreover, the optimal wavelet decomposition level is adaptively determined using a cost function-based method. The reconstructed signal, which no longer contains a background component, is normalized using a nonlinear and piecewise normalization method. The proposed method is faster and more accurate than some other phase retrieval approaches, which is illustrated with two test cases. 相似文献
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The multi-lateral shearing interferometers (multi-LSIs) are featured in the improved accuracy and noise resistance of wavefront reconstruction using phase differences in multiple directions. Nowadays the multidirectional phase differences are usually extracted from multi-LSIs’ interferogram using the fast Fourier transform (FFT) method, whose accuracy is limited by spectral leakage effect. To improve the measurement accuracy of multi-LSIs, a phase extraction method developed from moiré technique is proposed in this paper. Using virtual gratings with properly large carrier frequencies, the desired phase information in each of the multiple directions can be modulated into low-frequency domain of the corresponding moiré pattern with larger separations between unnecessary side lobes. In this way, low-pass filters with higher cut-off frequencies can be applied in moiré technique to reduce the inaccuracy induced by spectral leakage effect. Meanwhile, phase shifting method can be applied to extract phase information from a single fringe pattern with better noise resistance by easily introducing phase shifts in computer generated virtual gratings. Simulation results show that the proposed method has higher accuracy and better anti-noise performance than the FFT method when spectral leakage effect exists. To demonstrate accuracy of the proposed method, a null test experiment of the quadriwave LSI has been conducted and experimental results show that measurement accuracy of the quadriwave LSI can be significantly improved by substituting the FFT method with the proposed method in phase extraction process. 相似文献
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Methods for phase retrieval in digital speckle shearing interferometry (DSSI) with relatively large deformation are proposed using a single wavelength illumination with windowed Fourier filtering (WFF) and two-wavelength simultaneous illumination with iterative sine-cosine average filtering (ISCAF). For relatively large deformation measurement, WFF technique has a higher noise suppression capability than ISCAF technique but requires careful selection of the processing parameters, while ISCAF is a simple filtering with less parameter setting. Both methods for phase retrieval are discussed. Experimental results show that both methods are capable of noise suppression in the phase retrieval for relatively large deformation. 相似文献
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The windowed Fourier ridges (WFR) algorithm can be used to extract the frequency and phase information from an exponential or carrier fringe pattern. The selection of the window size for this algorithm is investigated in this paper. For exponential phase fringe patterns, the window size does not need to be adjusted according to the signal frequency. Hence the scaling strategy of the wavelet transform is not necessary. Instead, the window size should be selected according to the balance between the linear phase approximation error and the noise level. For carrier fringe patterns, the influence of the conjugate component should also be considered. However it can be ignored when the lowest frequency of the fringe pattern is higher than 1.5/σ (σ is used to represent the window size). 相似文献
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傅里叶变换成像光谱仪在遥感应用中是一种很重要的科学仪器,在傅里叶变换光谱仪信号处理中存在相位误差的问题,文章阐述了相位误差产生的原因,分析了由零点采样偏移带来的相位误差的非线性,说明了产生这种非线性的原因是干涉图为有限长的离散序列,从一个新的角度通过数学推导的结果给出了这种非线性的解释和表达。接着由相位误差的非线性讨论了Mertz相位修正方法中的相位插值可能存在的误差,分析了已有的研究中的较好的处理方法,并提出了一种改进这种误差的补零变换的方法。使用通过标准光谱库中的源光谱数据仿真的干涉数据,对方法进行了比较和验证,说明了补零变换法可以改善相位插值的误差以及在一些情况下的相位突变,得到质量更好的复原光谱。 相似文献
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A novel two-dimensional (2D) Gabor continuous wavelet transform (CWT) for phase retrieval and fringe filtering of speckle fringe patterns with spatial carriers is proposed. Theoretical analysis of 2D Gabor CWT is presented and results are compared with advanced fan 2D CWT using both the computer simulated and experimental speckle fringe patterns. It is shown that noise reduction by 2D Gabor CWT demonstrates better results than that of the advanced fan 2D CWT. Two-dimensional Gabor CWT is also compared with 2D Fourier transform and results show that 2D Gabor CWT algorithm has better noise immunity. 相似文献