两步相移实现投影栅相位测量轮廓术

提出一种新的投影栅相位测量方法--两步相移法。该方法只需两幅相移条纹图，因此计算量小，速度快。给出了实验及计算结果，并同四步相移法进行了比较，证明了该方法具有较高的精度。     

载波相移全息干涉计量

本文报道了一项称为载波相移全息干涉计量的自动相位估算的新技术。该技术的主要特点是不同相移的条纹图案可用双曝光全息重视。这样即可用来对与时间相关的问题进行自动相位估算。     

平行式向列液晶实现相移剪切电子散斑干涉术的研究

研究了向列型液晶的相位调制特性，采用平行式向列液昌作为相移器建立了相移剪切电子散斑干涉计量系统。该方法将相移技术引入到剪切电子散斑干涉术中，提高了检测精度，采用了相关条纹法求解相位，简化了计算；相移方法简单，可靠。用该系统进行应变场的测量实验，取得了满意的效果。     

用双图全息相移干涉法计算与时间有关的位相分布

提出一种双图全息相移干涉法．该方法可以用来计算与时间有关的位相分布，两幅全息干涉条纹图可以同时得到，并且有固定的９０°位相差．虽然两幅条纹图的位相可以随着时间变化，如环境影响，或载荷变化，但他们之间的位相差恒定．该方法利用二维傅氏变换，结合偏振相移法以及分光技术．     

基于复合光栅投影的快速傅里叶变换轮廓术

在实际傅里叶变换轮廓术测量中,获取条纹图的零频分量对傅里叶变换轮廓术的测量精度和测量范围有很大影响,甚至妨碍三维面形的正确重建。π相移技术常被用来消除零频分量对傅里叶变换轮廓术测量的影响,但它需要采集两帧具有π相位差的条纹图。这影响了傅里叶变换轮廓术测量方法的实时性。提出采用复合光栅投影来实现从一帧条纹图中消除零频对傅里叶变换轮廓术测量的影响,该复合光栅是由两个不同频率的载频分别调制与其方向垂直的两帧具有π相位差的条纹并叠加形成的。实验表明,同传统的π相移方法相比,提出的新方法没有明显降低π相移傅里叶变换轮廓术的的测量精度,因此能真正实现实时高速测量。     

基于正弦条纹投影的三维传感及其去包裹处理

采用液晶显示（LCD）投影仪产生的正弦条纹,用四步相移技术对物体进行了三维形貌测量,重点讨论了去包裹问题,对大面积相位间断区的模板标识及含离散相位间断点条纹图的去包裹总是提出了新的处理方法,给出了实际测量及计算结果。     

A digital spatial carrier for wavelet phase extraction

In this paper, we present a new method to digitally add a high-frequency spatial carrier in order to use the wavelet phase extraction algorithm, which leads directly to the phase without the unwrapping process. The method needs a fringe pattern and its π/2 shifted version. The application is performed with two shifted fringe patterns obtained from the phase shifting images of the thermomechanical study of an MOS power transistor. A comparison with the phase shifting results is made.     

Fourier transform profilometry based on composite structured light pattern

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.     

相位移法中的量化误差效应

对相位移测量技术中的条纹强度量化所引起的相位误差进行了定量研究，给出了相位测量误差与条纹强度误差之间的统计关系式，对条纹强度量化误差进行傅时叶级数展开，并利用条纹强度与相位的关系求得该级数的系数，进而得到的标准Ｎ幅算法的相位的解析表达式，最后对强度量化误差效应的一些影响因素进行了讨论。     

A comparison of phase shifting and fourier methods in the analysis of discontinuous fringe patterns

Phase Shifting Interferometry is a highly accurate data acquisition technique that efficiently utilizes several frames of information for each measurement. In this work, the advantages of phase shifting have been applied to a conventional moiré interferometer, yielding a system capable of recording phase shifted fringe patterns for both in-plane displacement components. Using this method, the phase of a wavefront of interest can be determined at each detector location, so that the resolution of the phase measurements is limited primarily by the detector discrimination and geometry. Unlike traditional Fourier fringe analysis, the noise rejection of phase shift processing algorithms does not degrade image fidelity in the presence of edges and discontinuities. A general discussion of both the phase shifting technique and the Fourier fringe analysis method is included to provide insight into the problems of processing discontinuous fringe patterns.     

A multi-purpose phase modulator for one beam ESPI

This paper proposes a simple, compact, practical, less nonlinear, less decorrelation and multi-purpose phase modulator for one beam ESPI which can be used perform both phase shifting and fringe carriering techniques. Theory together with experimental demonstrations are presented.     

A multi-purpose phase modulator for one beam ESPI

This paper proposes a simple, compact, practical, less nonlinear, less decorrelation and multi-purpose phase modulator for one beam ESPI which can be used perform both phase shifting and fringe carriering techniques. Theory together with experimental demonstrations are presented.     

Measurement of shock waves using phase shifting pulsed holographic interferometer

A phase shifting pulsed holographic interferometer was applied to the experimental study of the propagation of laser-induced shock waves over metal plates. A double-pulsed ruby laser was used to generate the shock waves and to make a holographic interferogram of the wave fields. The phase shifting method with a dual-reference beam solved the sign ambiguity problem in holographic fringe patterns and allowed a quantitative evaluation of the phase of the interference patterns. The transient surface profile and propagation behavior of the shock wave over plates were investigated from the holographic fringe patterns.     

Surface profile measurement of low-frequency vibrating objects using temporal analysis of fringe pattern

A simple and accurate algorithm (phase scanning method) is proposed for 3D surface contouring and dynamic response determination of a vibrating object. A sinusoidal fringe pattern is projected onto a low-frequency vibrating object by a programmable liquid crystal display projector. The fringe patterns are captured by a high-speed CCD camera with a telecentric gauging lens. Phase values are evaluated point by point using phase scanning method. From the phase values of each point on the object, the contour of the specimen at different instants of vibration can be retrieved. In this paper, a small vibrating coin is used to demonstrate the validity of the method and the experimental results are compared with test results on a stationary coin using four-step phase shifting and fast Fourier transform methods. The technique is especially useful in applications where the vibrating object has a complicated shape.     

基于双色条纹投影的快速傅里叶变换轮廓术

在实际傅里叶变换轮廓术测量中，获取的条纹图扩展的零频分量对傅里叶变换轮廓术的测量精度和测量范围有很大影响，甚至妨碍正确三维面形的恢复。π相移技术常被用来消除零频分量对测量的影响，但需要在测量系统中安装精密相移装置，并需要采集两帧具有π相位差的条纹图。传统傅里叶变换轮廓术中，完成精密相移需要较长的时间，影响了傅里叶变换轮廓术测量方法的实时性。提出了采用双色正弦光栅投影来实现从一帧条纹图中消除零频对傅里叶变换轮廓术测量的影响。该方法同传统的π相移方法相比，不需要相移装置，测量系统简单，并且能真正实现高速测量。     

Phase shifting algorithms for non-sinusoidal waveforms with phase shift errors

In phase shifting interferometry, phase errors due to harmonic components of a fringe signal can be minimized by applying synchronous phase shifting algorithms with more than four samples. However, when the phase shift calibration is inaccurate, these algorithms cannot eliminate the effects of a non-sinusoidal waveform. It is shown that by taking a number of samples beyond one period of the fringe pattern, phase errors due to the harmonic components of the fringe signal can be eliminated, even when there exists a constant error in the phase shift interval. A general procedure for constructing phase shifting algorithms that eliminate these errors is derived. A seven-sample phase shifting algorithm is derived as an example, in which the effect of the second harmonic component can be eliminated in the presence of a constant error in the phase shift interval.     

Frequency guided methods for demodulation of a single fringe pattern with quadratic phase matching

Phase demodulation from a single fringe pattern is a challenging task but of interest. A quadratic phase matching and frequency-guided regularized phase tracker (QFGRPT) and a quadratic phase matching and frequency-guided sequential demodulation (QFSD) for demodulation of a single fringe pattern are proposed. The algorithms are characterized by their improvements on both robustness and accuracy, which are realized by quadratic phase matching and frequency guided scanning strategy, respectively. Quadratic phase matching improves accuracy compared with the existing regularized phase tracker techniques and the frequency-guided sequential demodulation technique using linear phase matching. Frequency guidance ensures high robustness compared with the recently published path-independent regularized phase-tracking technique. Demodulation results from computer-simulated and experimental fringe patterns using the proposed methods are demonstrated and analyzed.     

基于快速傅里叶变换的实时相移校正算法

在相移测量剖面术（ＰＭＰ）中,提出了一种基于快速傅里叶变换的相移校正算法,利用最初多采的一幅条纹图的信息和傅里叶变换调制度模板,快速地计算出当前的相移值。采用该算法,能实时准确地控制投影光栅的移动,大大提高了测量系统的工和自动化程度,具有极大的实用价值。     

Analysis of phase distortion in phase-shifted fringe projection

This paper describes the analysis of phase distortion in phase-shifted fringe projection method. A phase distortion occurs when the phase shifting technique is applied to extract the phase values from projected fringe patterns in surface contouring. The phase distortion will induce measurement errors especially in the measurement of micro-components. The cause of such phase distortion is investigated and the influence of phase distortion on the measurement of micro-components is discussed. To eliminate the phase distortion, a continuous wavelet transform (CWT) is employed to extract phase values from object surface modulated fringe patterns. Principle of the proposed CWT phase extraction method is described and experiments are conducted to verify the proposed method. It is shown that by the use of CWT phase extraction method phase distortion induced in conventional phase-shifting technique can be completely eliminated.     

干涉仪自适应抗振的空间移相术

根据时域移相算法的概念,提出了一种空间移相术,它能够检测因外界振动导致条纹抖动而引起的干涉图样的空间相位变化.运用这种技术在TwymanGreen移相式干涉仪中建立了一套自适应抗振系统,它可以实时测量振动引起的相位变化大小,并通过反馈器件PZT实时校正干涉条纹的相位,使得干涉条纹稳定以保证光学测量的正常进行,与此同时PZT还作为移相器件.