干涉条纹的高准确度傅里叶变换分析

提出了一种可用于干涉条纹傅里叶变换分析的空间载波频率估计方法.通过干涉条纹的加窗切趾处理及旁瓣质心坐标的计算,得到空间载波频率的高准确度估计.基于傅里叶变换的位移定理,用估计的空间载波频率实现了载频的移除.模拟和实验结果表明此方法可以有效地抑制传统干涉条纹傅里叶变换分析中的载频移除误差和频谱泄漏误差.     

晶体锥光效应和相位测量

本文提出了一种新的以晶体锥光偏光干涉效应为原理的强度空间滤波器的方法以及用于傅里叶滤波准光干涉术进行相位测量的原理.这种方法不需要傅里叶变换透镜以及空间滤波器图案板.讨论了各种具体结构,分析了工作特性,叙述了能产生多种等位线条纹系统并可带有背景条纹.最后给出实验例子.     

光纤傅里叶变换光谱仪干涉图的对称化处理

偏离中心条纹的抽样以及光纤干涉仪的缺陷引起光纤傅里叶变换光谱仪(FFTS)输出的干涉图不对称,导致由傅里叶余弦变换计算得到的光谱带有相位误差,影响光谱的线型。文章首次将卷积方法应用到光纤傅里叶变换光谱仪中干涉图的对称化处理,利用干涉图的中心部分计算出相位误差,通过傅里叶变换得到了对称化处理函数,用卷积运算在时域完成了光谱的相位误差校正。实验研究表明,在FFTS中该方法能在时域有效地实现干涉图对称化,校正了光谱的相位误差。该方法不仅克服了双边干涉图的缺点,而且校正的结果有较高的准确度。     

基于希尔伯特变换的干涉条纹相位解调新算法

提出了一种新的应用希尔伯特变换解调干涉条纹相位的算法,可以从单幅干涉条纹图中解调出全场相位分布.在实际应用中,常借助傅里叶变换实现希尔伯特变换算法,但是会忽略负频率成分,造成相位信息的丢失.对于相位分布非单调变化的干涉条纹,提出了一种判断函数,用来计算相位信息零频率点的分布.利用相位的零频率点分布构造了一个二元模板,使用该模板对本文提出的两次希尔伯特变换法产生的包裹相位图进行修正.对修正后的包裹相位图进行解包裹处理,可以得到连续的全场相位分布.对该方法用计算机模拟进行了验证.     

有损压缩JPEG在载频条纹图分析中的应用研究

探讨了基于JPEG的有损压缩方法在载频条纹图分析中的应用前景。简介了当今流行的JPEG有损压缩技术和傅里叶变换轮廓术。使用专业软件对傅里叶变换轮廓术中拍摄的载频条纹图进行各种压缩比的压缩,解压后再解调出相位,与未经压缩的原图解调出的相位进行比较。将其相位误差与相位移法解调出的相位误差进行了对比,指出相对于相位移法而言,傅里叶变换轮廓术具有滤波的作用,对其拍摄的载频条纹图,应用JPEG压缩算法是可能的,解调出来的相位误差更小。     

基于窗口傅里叶变换剪切干涉法波前检测

提出了一种利用二维窗口傅里叶变换从径向剪切干涉条纹中准确得到波前的重建技术。首先对剪切干涉条纹做二维窗口傅里叶变换,设置阈值和频率积分范围后,进行二维窗口傅里叶逆变换,然后对包裹相位做去载频和相位展开处理得到相位差分布,最后使用波前迭代算法从相位差中复原实际波前。模拟计算表明,使用该方法最大相位复原误差为0.82%,均方根值为0.020 9 rad,实验结果验证了该方法的有效性。同时也对窗口傅里叶变换的关键参数,如窗函数的选择、窗口大小的确定以及阈值的选取等进行了简要讨论。与传统傅里叶变换法(FFT)相比,基于窗口傅里叶变换的剪切干涉波前检测法有更高的精度和稳定性,为波前检测提供一种新的处理方法。     

基于希尔伯特变换的干涉条纹相位解调新算法

提出了一种新的应用希尔伯特变换解调干涉条纹相位的算法,可以从单幅干涉条纹图中解调出全场相位分布.在实际应用中,常借助傅里叶变换实现希尔伯特变换算法,但是会忽略负频率成分,造成相位信息的丢失.对于相位分布非单调变化的干涉条纹,提出了一种判断函数,用来计算相位信息零频率点的分布.利用相位的零频率点分布构造了一个二元模板,使用该模板对本文提出的两次希尔伯特变换法产生的包裹相位图进行修正.对修正后的包裹相位图进行解包裹处理,可以得到连续的全场相位分布.对该方法用计算机模拟进行了验证.     

成像型任意反射面速度干涉仪数据处理方法

 采用傅里叶变换方法,列出了对成像型任意反射面速度干涉仪得到的干涉条纹图进行处理的过程。利用文献结果,处理了冲击波整形时产生的有间断干涉条纹图,对处理结果进行了分析。结果表明：条纹图要干净,条纹间距清晰、均匀,应使用１维傅里叶变换的方法处理条纹图,减小滤波的难度。研究了冲击波测试当中条纹丢失的问题,提出了间断条纹图间断起始点相位确定的方法。对透明和不透明靶产生条纹图的不同进行了讨论,得出对透明靶产生的条纹图应采用适当的条纹外延技术进行预处理后再进行常规处理。     

基于条纹中心线的载波散斑条纹解调方法

针对传统傅里叶变换法在处理含有多突起的载波散斑条纹图时,由于存在频谱展宽会出现严重的解调相位失真,提出了一种基于条纹中心线的载波散斑条纹解调方法.根据载波调制时所采用平行调制方式和倾斜调制方式,分别从理论上对相关的中心线解调法进行数学推导,并进一步采用最小二乘三次曲面拟合法获得被测物面全场的离面位移信息.实验结果表明:利用上述中心线解调法和曲面拟合法能解调出复杂的载波条纹图,并获得具有亚像素定位准确度、连续光滑的全场离面位移信息.     

傅变光谱仪数据处理中相位误差非线性的分析及对Mertz相位修正方法的讨论

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。     

Accurate carrier-removal technique based on zero padding in Fourier transform method for carrier interferogram analysis

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.     

移相器微位移旋转误差的分析及测试

以压电陶瓷(PZT)微位移器为主要研究对象, 引入一种处理静态干涉图的新方法--虚光栅移相叠栅条纹法,设计实验对一台实际使用的移相器微位移旋转误差进行测试研究,对其引起的波面旋转情况进行了定量的计算分析,并给出测试结果.用虚光栅移相叠栅条纹法处理实验中加有载频的干涉图时,不需要使用任何移相器件,可以进行动态位相的检测,整个移相过程用计算机进行控制,避免了引入额外的移相误差.     

Identification of nonlinear recording error in phase shifting interferometry

The phase shifting method for quantitative fringe pattern analysis provides high accuracy if stringent requirements on the component interferogram recording are met. In the paper the issue of detection and identification of error sources in the two-beam interferogram phase shifting experiment is discussed. The phase shift angle histogram and lattice-site representation are applied for that purpose. Special attention is paid to possible nonlinear recording of component interferograms in the presence of linear and nonlinear phase step errors. Four and five step phase shifting algorithms are considered. The superiority of the lattice-site representation is shown. In the case of phase steps equal to π/2, however, the lattice-site representation of shift angles for five frame algorithm does not allow to detect recording nonlinearity. The four frame counterpart shows to be very helpful in this respect. Its properties related to the fringe pattern profile under study, including a defocused Ronchi grating, are discussed.     

Uncertainty analysis of whole-field phase-differences retrieved from ESPI fringe patterns by using the Fourier transform method (FTM)

We have evaluated the uncertainty associated with the whole-field phase-differences retrieved by using the Fourier transform method (FTM), from a fringe pattern generated by electronic speckle pattern interferometry (ESPI). The phase-differences were induced by applying load to an elastic sample. The FTM involved the Fourier transform application to the fringe pattern, the isolation of the term carrying the phase information by applying a band-pass filter in the spatial frequency domain, and then the inverse Fourier transform application. Since the fringes in the analyzed pattern were adequately open, the FTM outcomes were presumed to be mainly affected by errors in the determination of both the width and the location of the applied filter mask. The influence of these error sources was assessed by using a Monte Carlo-based computer simulation. It implied evaluating the phase-differences a large number of times under the influence of the involved error sources. We found that the phase uncertainty depends strongly on the width of the applied filter mask; the influence of the other error sources considered into the uncertainty propagation was significantly smaller.     

干涉条纹图的处理方法研究

提出了干涉条纹图处理的新方法。基于干涉条纹图的特征的分析 ,提出了一种适用于各种不同形状的干涉条纹图的平滑和细化方法 ,该算法不仅适用于不同干涉系统的条纹分析 ,而且细化后的单像素条纹光滑、分叉少、不断裂 ,为后续数据处理奠定了基础。     

A study of fringe pattern trace and analysis

In this paper,the gometric center and centroid method are suggested to tracecenter location of a close fringe pattern.The fringe pattern of the interferogram is analysed byusing the general Fourier method.The analytic accuracy is controlled by using P-test methodof statistics.The analytic accuracy and sampling speed of the fringe pattern depend on thequality of the interferogram and the numbers of the sampling points.     

空间载频条纹相位分析法中的相位不确定性

分析了单频、双频空间载频光学条纹相位分析技术中的相位不确定性问题,提出采用两频率之比为无理数的双频载频条纹,相位可完全确定,并提出了基于两频率之比为无理数的空间载频条纹相位确定算法,给出了实验结果。     

基于Gabor滤波的散斑条纹图平滑方法

提出了一种基于伽博(Gabor)滤波的散斑条纹图平滑方法.通过加窗傅里叶运算提取散斑条纹图的条纹频率和条纹梯度方向,并利用它们确定具有频率和方向选择性的Gabor滤波器对散斑条纹图进行Gabor滤波.数值模拟和实验结果表明,该方法在滤除散斑噪声的同时能够有效的保留散斑条纹图的条纹结构,为从单幅散斑条纹图中进一步提取条纹相位场奠定了良好的基础.     

Shifted-phase calibration for a 3-D shape measurement system based on orthogonal composite grating projection

This paper proposes a novel method for reducing measurement error caused by spectrum overlapping in orthogonal-composite-grating-based 3-D measurement method. For 3-D measurement systems based on orthogonal composite grating projection, spectrum overlapping causes phase of each deformed phase-shifting fringe changed differently, which violates the principle that the shifted phases between adjacent deformed fringes must be equivalent to 2π/3, and therefore results in phase measurement error. The proposed shifted-phase calibration method is based on that phase variation of each deformed fringe is independent of height and reflectivity of the measured object. Three composite gratings are projected on the reference plane, and each carrier channel includes three phase-shifting gratings needed in phase measuring profilometry (PMP). Because the adjacent phase-shifting fringes demodulated from the same carrier channel have the phase difference of 2π/3, we can respectively calculate the reference plane's phases of three carrier channels by the phase algorithm of PMP method, and the shifted phases between them are obtained. When an object is measured, the shifted phases between deformed phase-shifting fringes can be calibrated. A new 3-D measurement mathematical model is set to reconstruct object. Our experiments prove that the proposed method can effectively restrain the effect of spectrum overlapping and improve measurement accuracy almost one times.     

A method for fringe normalization by Zernike polynomial

A new approach for fringe normalization by Zernike polynomial fitting to cancel background illumination in an interferogram is proposed. With this method, background illumination can be suppressed, high frequency noise is immunized and the contrast is improved by normalization. The main idea for this paper is to use the Zernike polynomial fitting interferogram to cancel background illumination; the high frequency noise is then filtered by a Wiener filter. Finally, the paper uses the method of local region contrast modulation to enhance fringe contrast. This method can overcome the problem of the non-uniformity illumination of fringe patterns resulting from the marginal reflection of optical components and a non-uniformity light source