用双波长法和相移法确定光弹性参数

分别采用双波长法和相移法研究了光弹性条纹的自动分析技术。分别采用波长为630nm和532nm的激光作光源,根据在不同光场下获得的等差线条纹光强变化,可实现等差线条纹的自动定级。同时,提出了新的图像处理方法,结合等倾线相移技术实现了第一主应力方向的全场确定,再以Tardy补偿法为基础,提出了全场等差线的相移方法。该文结合经典的实验对比,详细比较分析了这两种方法的优缺点。结果表明:该文提出的新的相移方法可实现光弹性条纹的自动化分析。     

基于白光相移干涉术的微结构几何尺寸表征

将Carré等步长相移法与白光垂直扫描相结合形成了一种白光等步长相移算法,该方法快速、准确、非接触,垂直分辨力可达亚纳米级.测量系统集成了Mirau显微干涉物镜,并通过高精度压电陶瓷纳米定位器带动物镜进行垂直扫描.分析了Carré法应用于白光干涉信号的相位提取的精度,对不同扫描步距以及不同信噪比情况下的测量进行了计算机仿真,确定了测量参数.结合重心法将相位计算的数据范围直接定位于干涉信号的零级条纹,从而省去了相位解包裹过程.通过对微谐振器和标准台阶的测量说明了该方法的有效性,并使用白光相移干涉、白光垂直扫描和单色光相移干涉对44 nm标准台阶进行了测量,并对测量结果进行了比较.     

Intelligent System for Mask Phase-Shifter Design

讨论了一个用于相移掩模智能设计的专家系统。这个系统包括输入输出系统，仿真系统，知识库系统，人—机接口，黑板系统。它有一个包括图形获取、预处理、模式抽取、搜索与解释、图形复合与输出等环节的工作过程。系统的软件实现运用了面向对象的表示方法。     

Phase evaluation of speckle patterns during continuous deformation by use of phase-shifting speckle interferometry

A method for measurement of continuous displacements that uses phase-shifting speckle interferometry is presented. The initial random phase of the speckle pattern is evaluated by phase shifting before deformation. The changing phase thereafter is evaluated from only one image at a time by a least-squares algorithm. The technique can be used for measuring transients and other dynamic events, heat expansion as well as other phenomena, for which it is difficult to accomplish phase shifting during deformation. Theory along with computer simulations and experimental results are described.     

Full-field optical coherence tomography by achromatic phase shifting with a rotating polarizer

We demonstrate two-dimensional detection optical coherence tomography (OCT) using achromatic phase shifting with a rotating polarizer. This phase shifting, which experiences a light beam with a cyclic change in its polarization state, is, in principle, independent of wavelength. We simulated the wavelength dependence of an achromatic phase shifter using Jones calculus and found that the achromatic region exceeded 145 nm when the deviation of the phase retardation was less than +/- 0.5 degrees. Using the achromatic phase shifter and a conventional phase-shift calculation method, we obtained en face OCT images of an onion at different depths. This method is effective to enhance the quality of OCT with an ultrabroad-spectrum light source.     

采用罗奇光栅离焦投影的位相测量轮廓术

本文提出一种采用罗奇光栅离焦投影的位相测量轮廓术。给出由离焦引起的光学低通滤波和N-位相算法表征的数字滤波的解析描述。证明由于采用罗奇光栅离焦投影而引起的误差只具有很小量级,在大多数实际应用中可以忽略。文中给出了计算机模拟和实验结果。     

Robust, common path, phase shifting interferometer and optical profilometer

We describe an improved implementation of our previously reported common-path, phase shifting, and shearing interferometer. Using a time-multiplexed phase shifting scheme, we demonstrate higher sampling resolution, better light sensitivity, and use of arbitrary phase shifting algorithms. We describe microscopic imaging of the surface profile of a copper-plated silicon wafer and demonstrate that the system is vibration insensitive with approximately lambda/100 repeatability. In a more general discussion of our method, we describe the different functional elements and suggest alternative designs and improvements. Possible uses include full-field coherent imaging and high dynamic range wavefront sensing, which we briefly discuss.     

MEMS显微干涉测量系统中相位提取算法的选择与分析

描述了一种基于相移显微干涉术的MEMS测试方法,达到了纳米级分辨力．从理论上分析了4种常用相移算法对测量过程主要噪声（相移器的移相误差和探测器的非线性响应误差）的抑制作用,并选定了适合本系统的Hariharan算法．通过对经过美国国家标准研究院（NIST）认证的一个台阶高度的测量,验证了各种算法的测量精度,说明Hariharan算法对噪声有更强的抑制作用,其测量重复性在亚纳米量级．     

Evaluation of core characteristics of magnetic phase shifters for thyristor amplifiers

The exciting current characteristic is suggested as a new method of evaluating the core characteristic. The phase shifting characteristic and the difference between a positive and negative waveform of a balanced half-wave type magnetic phase shifter are calculated by using the exciting current characteristics of cores employed in it. From these theoretical analyses, it can be determined that the difference of a positive and negative waveform is caused by a difference of exciting current characteristics of two cores used in it, and it becomes larger in proportion to larger control-circuit resistance. An experiment was performed using two pairs of cores, in which one pair of exciting currents are identical and the other pair differ. Theoretical results are in good agreement with the experimental results.     

用于变压器损耗校准的移相装置研制

针对变压器损耗测量系统(TLMS)校准中,对功率因数可调高压大电流信号源的需要,开展了移相技术研究及装置研制。装置在机理上利用希尔伯特变换,对输入信号进行卷积运算,得到正交参考信号;然后通过双参数的矢量合成技术生成相位可调的输出,从而产生不同功率因数的试验信号。基于此技术,搭建并实现了Compact RIO平台的移相装置。同时利用Compact RIO作为硬件平台、LabVIEW软件实现可视化操作,设计了相位测量仪器,并结合相角电压表Clark-Hess 2600对移相装置的稳定性和分辨率进行实验验证。实验结果表明:所研制的移相装置分辨率、稳定性及准确度优于0.001°。     

Spatial phase shifting for pure in-plane displacement and displacement-derivative measurements in electronic speckle pattern interferometry (ESPI)

Hitherto no method, to our knowledge, was known to incorporate spatial phase shifting for the measurement of pure in-plane displacements. We demonstrate that the modified Duffy two-aperture configuration [Opt. Lett. 22, 1958 (1996)], which is sensitive to only the in-plane displacement component and offers increased sensitivity, lends itself to measurement with spatial phase shifting. The configuration can also be used for obtaining displacement derivatives by the introduction of shear with the tilt of a mirror.     

Motion error correction of range migration algorithm for aircraft spotlight SAR imaging

Since a motion error is the main phase error source in the aircraft synthetic aperture radar, several reconstruction algorithms with motion error correction have been developed. An efficient motion compensation via the known motion error information is proposed. Specifically, the proposed method is based on the subarea technique with shifting and the subaperture technique via the mean values of the motion errors. Then, using the extended Taylor approximation and the principle of the stationary phase, the motion errors are corrected through compensation at the mixing stage and the Stolt interpolation stage.     

Precise and fast phase wraps reduction in fringe projection profilometry

Phase wraps in a 2D wrapped phase map can be completely eliminated or greatly reduced by frequency shifting. But it usually cannot be optimally reduced using conventional fast Fourier transform (FFT) because the spectrum can be shifted only by a integer number in the frequency domain. In order to achieve a significant phase wrap reduction, we propose a fast and precise two-step method for phase wraps reduction in this paper, which is based on the iterative local discrete Fourier transform (DFT). Firstly, initial estimate of the frequency peak is obtained by FFT. Then sub-pixel spectral peak with high resolution is determined by iteratively upsampling the local DFT around the initial peak location. Finally, frequency shifting algorithm that operates in the spatial domain is used to eliminate phase wraps. Simulations and experiments are conducted to demonstrate the superb computing efficiency and overall performance of the proposed method.     

Spatial mismatch calibration using circular carrier technique in the simultaneous phase shifting interferometry

In most simultaneous phase shifting interferometry (SPSI) systems, a group of phase shifting interferograms are captured simultaneously at the different physical locations to retrieve the phase. The data of different interferograms should be spatially matched correctly, which is hard to realize by existing methods or this spatial mismatch will lead to phase retrieving error. In this paper, a spatial mismatch calibration method is proposed, where the circular carrier is introduced in the interferograms of the SPSI system, and the modulating phases of any two interferograms can be retrieved by the demodulation technique of circular carrier interferogram. The slope of the difference between these two phases is proportional to the mismatch value, so this error can be extracted and the experiment setup calibrated. The main error sources of the proposed method are analyzed with the conclusion that its match precision can be achieved up to 0.5 pixel. In addition, the simulated interferograms and actual interferograms captured in a SPSI system are processed to validate our proposed method.     

Effects of Window Size on Accuracy and Spatial Resolution in Windowed Phase‐Shifting Digital Holographic Interferometry1

Abstract: Phase‐shifting digital holographic interferometry is a new method to measure displacement distribution on the surface of an object. Usually holography has speckle noise, which leads to a large error in the analysis of displacement and strain distributions. We previously proposed windowed phase‐shifting digital holographic interferometry (windowed PSDHI). The use of this method leads to accurate displacement analysis, decreasing the effect of speckle patterns. However, noise reduction involves a defect, which renders the spatial resolution low. In this paper, by comparing the conventional noise reduction method using spatial averaging with the windowed PSDHI on spatial resolution, the effectiveness of noise reduction is discussed.     

Interferometric phase reconstruction by nonuniform shifting of the reference beam

A method for phase measurement in common-path interferometers, believed to be novel, is presented. We use the property of phase reconstruction algorithms, such as the Carré and Hariharan algorithms, that do not require uniform phase across the reference beam. Only the ratio of the phase steps must be the same at each pixel. We show phase measurement and reconstruction in a common-path interferometer by shifting either the tilt or the focus of the reference wave front. We present a theoretical explanation of phase measurement using this property. We also present results from a proof-of-principle experiment using a scatterplate interferometer, in conjunction with the tilt phase-shifting technique, to measure the reflected phase of a test optical element. Furthermore, we present a computer simulation to demonstrate the mathematical validity of this measurement technique using defocus shifting, rather than tilt shifting, in the reference wave front.     

Pixelated mask spatial carrier phase shifting interferometry algorithms and associated errors

In both temporal and spatial carrier phase shifting interferometry, the primary source of phase calculation error results from an error in the relative phase shift between sample points. In spatial carrier phase shifting interferometry, this phase shifting error is caused directly by the wavefront under test and is unavoidable. In order to minimize the phase shifting error, a pixelated spatial carrier phase shifting technique has been developed by 4D technologies. This new technique allows for the grouping of phase shifted pixels together around a single point in two dimensions, minimizing the phase shift change due to the spatial variation in the test wavefront. A formula for the phase calculation error in spatial carrier phase shifting interferometry is derived. The error associated with the use of linear N-point averaging algorithms is presented and compared with those of the pixelated spatial carrier technique.     

相移掩模方法及其一维数值模拟

相移掩模方法是一种新的光刻技术，它可以提高现有光刻设备的分辨率，使超大规模集成电路及二元光学的制作迈上一个新台阶。本文介绍了相移掩模方法的基本原理，用部分相干光成象理论分析了用于光刻的投影照相系统的成象特性，导出了一维成象的简化公式，对一维光栅结构进行了计算机数值模拟并给出了模拟结果。     

A minimum zone method for evaluating flatness error of gage blocks measured by phase‐shifting interferometry

Abstract

A new method called “Control Plane Rotation Scheme (CPRS)” has been developed here for the analysis of flatness error in terms of the minimum zone definition, which conforms to the ISO/R1101 specification. An application of the phase‐shifting interferometry was performed for on‐line measurement of gage blocks. Experimental results were quite consistent with the specified grade of the inspected gage block with only an uncertainty of up to 0.005 μm.     

Spatial phase shifting in electronic speckle pattern interferometry: minimization of phase reconstruction errors

The advantages of spatial phase shifting (SPS) compared with temporal phase shifting in the field of electronic speckle pattern interferometry are described. Some periodic phase reconstruction errors occurring in SPS are discussed. It is shown that these errors become minimal for a spatial phase-shift angle of 2pi/3. Furthermore, a modified phase reconstruction formula is presented by which the noise in the reconstructed phase map is reduced.