高加速度超精密激光外差干涉测量模型

为了精确地描述激光外差干涉在高加速度超精密测量中加速度对位移测量精度的影响机理与规律,建立了高加速度超精密激光外差干涉位移测量模型.通过分析测量棱镜三维运动对多普勒频移的影响,推导出高加速度激光外差干涉位移测量模型.理论分析和仿真实验表明,当测量加速度为9m/s2,匀加速运行的位移为500mm时,由于加速度变化引起的相对论性效应对测量精度的影响为5nm.高加速度超精密激光外差干涉位移测量模型的建立,可提高激光外差干涉在高加速度超精密测量中的测量精度,为激光外差干涉在高速和超高速测量领域的应用提供了理论依据.     

两米光栅——线纹自动测量仪（一）

描述了一台能够对长度达１ｍ的线纹尺和长度达２ｍ的光栅尺（线位移传感器）进行测量的激光干涉仪，干涉仪设计成了双干涉光路系统，以消除光栅尺安装引入的阿贝误差，这台测量仪采用干涉条纹计量原理，对光栅尺和线纹尺的线值精度进行检测，并能对光机信号的质量进行评价。测量过程中，对空气折射率实现了实时修正。     

光栅计量型的垂直扫描位移工作台及其误差分析

为满足精密测量中垂直扫描白光干涉以及千分表、电感位移传感器、表面粗糙度触针位移传感器标定对垂直方向的高精度定位和高分辨率运动要求,研制出一种纳米级垂直扫描位移工作台.该工作台采用柔性铰链结构,压电陶瓷驱动位移,满足纳米级微位移驱动要求,同时利用两级杠杆放大结构,扩大了位移行程.针对压电陶瓷驱动的位移随电压变化的非线性特点,利用衍射光栅对压电驱动进行实时监控,对这种非线性误差进行实时补偿.衍射光栅固定在工作台的微定位板上,工作台的移动量可由衍射光栅二次衍射干涉后产生的条纹变化得到.根据衍射光栅的计量特点,分析垂直扫描位移工作台测量误差的主要影响因素.通过试验验证,优化系统误差,进一步提高了垂直扫描位移工作台的定位精度.     

共路激光干涉测量系统的研究

激光干涉测量系统在精密测量领域占有重要地位,它对温度变化、大气变化、激光波长变化、机械安装误差和外界振动等比较敏感,影响系统的测量精度和稳定性。针对此情况,该文提出一种新型的激光干涉光路,两光臂呈完全共路结构,使干涉条纹信号具有极强的抗干扰能力;对光路进行抗干扰分析和理论推导;构建位移测量系统,进行系统测试实验和误差分析。实验表明,本系统测量分辨力0.72nm,合成标准不确定度5．2nm（k=2）,运行速度0．56mm／s,量程0．01mm。     

基于干涉条纹移动量的非接触振动测量研究

为了实现大振幅、高带宽振动的非接触精密测量,本文提出了一种全新的光学测量系统.两束相干光的远场干涉条纹位置与两束光之间相位差有关,相位差的变化将引起干涉条纹移动.获取主条纹的位置,可以计算两束光之间的相位差,基于此可以还原物体的振动位移量.对振幅为10μm的单频余弦信号以及频率为44.1 kHz的声音信号仿真还原结果表明,本文所提光学系统和还原算法可以还原出亚微米级的振动信号,并能准确还原出音频信息.     

双衍射光栅位移传感器原理及应用

介绍了一种双衍射光栅位移传感器,给出了其基本结构,并从多普勒效应的角度分析了其工作原理,给出了双衍射光栅产生的干涉条纹的接收方式和相应的光电信号的处理方法。该传感器与精密位移工作台组合成的表面粗糙度测量系统,对粗糙度样板进行了实测,结果表明该传感器能满足表面粗糙度测量要求。     

激光两座标测量仪

本文扼要介绍最近研制的激光两座标测量仪的主体结构、所采用的基本干涉测长系统、以及由此演变而来的可补偿阿贝原则误差的干涉系统、小角度干涉仪、空气折射率干涉仪等共四种干涉系统。还介绍了为提高仪器导轨运动精度而采用的工作台运动的小角度和直度误差的随机检测和伺服校正系统,以及测头沿横向运动的直度检测和修正系统。对应用激光干涉测长中使用的细分和单位变换方法及两座标定位测头也作了简单介绍。     

基于光纤干涉仪的振动测量技术

本文介绍了基于光纤Mach-Zchndcr干涉仪的振动测量系统,用线阵CCD测量条纹动态位移,实现了光纤干涉条纹图像的连续采集.针对干涉条纹图像噪声的特点完成了低通滤波器的设计、图像的平滑处理,消除了干涉条纹中心的定位误差.文章绘制了干涉条纹位移曲线并对其进行了离散傅里叶变换,给出了所测振动的频谱特性.最后讨论了测量系统的灵敏度以及影响测量精度的因素,为了能够辨别条纹的移动方向,指出了条纹最大允许的移动速度限制,给出了实验结果.     

标准硅球直径精密测量系统的设计

基于多光束干涉的基本原理，导出了使用斐索干涉仪测量硅球直径多光束干涉光强分布的精确公式。针对目前的硅球直径测量系统忽略了多次反射对干涉信号造成的影响和系统中固有的条纹清晰度低的问题，研究了多次反射对干涉信号造成的误差，结果表明其最大光强误差可达到8％。通过对光学干涉系统结构设计和元件参数选择，最大限度地优化了干涉条纹的可见度，并设计出零背景光强标准硅球直径精密测量系统。数值模拟结果表明，该系统不仅极大地提高了干涉条纹对比度、消除了背景噪声，而且可通过改变透镜焦距调节干涉条纹的强度以达到CCD的最佳工作范围，从而提高了光强信号的测量准确度。     

一种基于Matlab的干涉条纹自动处理方法

对接触式干涉仪量块检定时产生的两种干涉条纹进行了研究,图像整体采用傅里叶级数曲线拟合法,实现干涉暗条纹大致定位.局部采用最小二乘二次曲线拟合法,确定干涉暗条纹中心的精确位置及暗条纹个数.利用Matlab和VC平台进行编程,快速有效地实现了干涉条纹中心位置的自动判读. 该方法已应用在中国计量科学研究院接触式干涉仪的量块检定中.     

基于计算全息的无衍射光莫尔条纹三自由度测量方法研究

针对工作台运动误差,提出了一种基于计算全息的无衍射光莫尔条纹三自由度测量方法。通过液晶空间光调制器(SLM)生成无衍射光,利用两束无衍射光干涉生成莫尔条纹。设计了无衍射光莫尔条纹三自由度测量光路,建立了三自由度运动误差数学模型,并用几何分析法将三种运动误差(偏摆角、滚转角和俯仰角)进行分离。利用旋转台模拟不同大小的三自由度运动误差,带有误差信息的无衍射光和莫尔条纹图案分别由CCD1和CCD2接收。实验结果表明,通过光斑中心偏移量计算出的实际运动误差值接近理论值,测量误差不超过0.0104°,验证了无衍射光莫尔条纹三自由度测量系统的可行性与正确性。     

Generation of carrier fringes in holography and shearography

Double-exposure holography and double-exposure shearography are often used together with the carrier fringe technique, which requires additional shifting of the light source in a prescribed manner between exposures. In the holographic carrier fringe technique, difficulty in prescribing a suitable movement of the light source may be alleviated through visualization of the moiré fringes that are reconstructed by slight displacement of two overlaid families of ellipsoids in a holodiagram. Because shearography is the first differential of holography, it is often impractical to perform two successive optical differentiations on the ellipsoids to visualize the shearographic carrier fringes. A simple method of discerning holographic and shearographic carrier fringes is described. The method is based on the hyperboloids in a holodiagram that represent Young's (interference) fringes produced by the interference of two point sources. The hyperboloids are analogous to holographic carrier fringes, whereas the moiré patterns reconstructed from two overlaid hyperboloids are analogous to shearographic carrier fringes. Use of this method for explaining the formation of deformation fringes in plate bending, as well as the effect of light-source movement on the deformation fringes, is also illustrated.     

Vibration-compensated interferometry system using phase-modulating interference fringe subdivision technology

An innovative vibration-compensation method, with phase-modulating interference fringe subdivision technology, is described. It simulates fringe movement by the phase difference of signals and can detect the fringe movement with an accuracy of 1/400 fringe spacing using this subdivision technology. A closed-loop vibration-compensation system is built, and the measurement of an interference fringe movement and a vibration-compensation test are successfully demonstrated. Because of this new method and a new feedback algorithm that was introduced, interference fringes can be stabilized at any preset phase position in real time. Compared with known methods, this method is simple and inexpensive, as well as effective.     

Measuring the refractive indices of liquids with a capillary tube interferometer

A theoretical analysis of the fringe pattern produced by a capillary tube interferometer is presented, which is expected to be two-beam interference, and a computer program to simulate the interference fringe pattern is established. By comparing the simulated fringe pattern and the experimental fringe pattern, the refractive index of the liquid can be given when the two fringes coincide best. The results of this method are close to those of the Abbe refractometer.     

Bandwidth in Dichromated Gelatin Holographic Filters

Refractive volume gratings in dichromated gelatin film have been studied. The swelling of the emulsion during developing leads to displacement of the interference fringes from the positions observed for the exposure set-up and the fringes are smoothly curved rather than irregular. The effects of the displacement are studied in exposed and developed holograms by examining the reconstruction angle and spectral bandwidth when using white light reconstruction. The influence of construction geometry and absorption on spectral bandwidth is illustrated with experimental results.     

Far-field interference from a sphere and its applications

A theoretical model of far-field interference from a sphere has been established, and its applications have been investigated. When two coherent parallel laser beams shine on a smooth sphere surface from opposite directions, the reflected lights form interference fringes at far field. The fringes have hyperbolic shapes and are not uniformly distributed. This paper derives a method for calculating the path-length difference between two parallel reflected lights, analyzes the interference field, and discusses reasons that cause the fringe density variations. A formula for calculating the highest orders of interference fringes is also provided. A method for using a spectrometer, CCD camera, and computer to measure the sphere diameter is demonstrated. The results agree with those from an Abbe comparator. The theory and methods are also suitable for measuring diameters of smooth cylinders.     

Three-wavelength electronic speckle pattern interferometry with the Fourier-transform method for simultaneous measurement of microstructure-scale deformations in three dimensions

We present the simultaneous measurement of three-dimensional deformations by electronic speckle pattern interferometry using five object beams and three colors. Each color, corresponding to an orthogonal direction of displacement, is separated through dichroic filtering before being recorded by a separate CCD camera. Carrier fringes are introduced by tilting the beam path in one arm of each of the three interferometers. The measured deformation modulates these carrier fringes and is extracted using the Fourier-transform method to achieve high displacement sensitivity. The field of view is on the order of a millimeter, making the system suitable for study of microstructural deformations. We compare experimental results with calculated values to validate out-of-plane and in-plane deformation measurements and demonstrate sensitivity on the order of 10 nm.     

Automated determination of best focus and minimization of optical path difference in Linnik white light interferometry

It is difficult to search for interference fringes in Linnik white light interferometry with an extremely short coherence length because of the optical path mismatch of two interference arms and the defocus of the reference mirror and the test surface. We present an automated method to tackle this problem in this paper. The determination of best foci of the reference mirror and the test surface is implemented by the astigmatic method based on a modified commercial DVD pickup head embedded in the interference system. The astigmatic method is improved by setting a threshold value in the sum signal to truncate the normalized focus error signal (NFES). The truncated NFES has a monotonic relationship with the displacement of the test surface, which removes the position ambiguity of the test surface during the autofocus process. The developed autofocus system is confirmed experimentally with a dynamic range of 190?μm, average sensitivity of 70 mV/μm, average standard deviation of 0.041?μm, displayed resolution of 4.4 nm, and accuracy of 55 nm. The minimization of the optical path difference of two interference arms is carried out by finding the maximum fringe contrast of the image captured by a CCD camera with the root mean square fringe contrast (RMSFC) function. The RMSFC function, combined with a 4×4 pixel binning of the CCD camera, is recommended to improve the computational efficiency. Experimental tests show that the automated method can be effectively utilized to search for interference fringes in Linnik white light interferometry.     

角位移Fabry-Perot干涉测量

提出了一种基于Fabry-Perot板干涉的角位移测量新方法。此方法采用函数近似,只需将初始入射角确定在40°到50°之间,即可由角位移与干涉信号条纹数变化间的函数关系,高精度测量角位移。解决了采用F-P板干涉法测量角位移需精确确定入射光初始角的问题。使用计算机处理采集的干涉信号,对干涉条纹进行细分,实现干涉信号相位测量的高分辨力。理论模拟和实验结果得出本方法可以实现精度为10-5rad数量级的角位移测量。该方法的测量装置采用带尾纤的半导体激光作为光源,由自聚焦透镜准直,出射光束直径为0.5mm,使探测头为小光斑。该装置结构简单,能实现小型化。