利用激光干涉测金属线胀系数

文中分析了洛埃镜干涉实验中 ,由金属受热膨胀引起的洛埃镜位置变化对干涉条纹间距的影响 ,导出金属的线胀系数与干涉条纹密度变化之间的关系。介绍了用CCD图象处理技术与计算机技术相结合 ,测量干涉条纹间距的方法     

虚拟光栅变频投影三维测量技术的研究

虚拟光栅变频投影三维测量技术采用多光束干涉条纹形成虚拟余弦光栅,将虚拟余弦光栅投影到被测物体上得到被物体形貌调制的变形虚拟光栅。通过调整多光束干涉的楔角改变虚拟光栅频率,将两幅不同频率的变形虚拟光栅经过光学接收系统成像在CCD像机上,对CCD像机记录的变频变形光栅图像进行综合处理从而获取被测物体的三位形貌。本文给出了这种测量技术的原理,实验结果表明,采用变频虚拟光栅投影三维形貌测量技术可以有效地解决三维测量中被测物体高度变化率过大引起相位展开困难的问题。     

利用白光扫描干涉测量表面微观形貌

由于激光显微干涉只能测量表面微观形貌的相对高度值,不能进行绝对测量,本文提出了白光显微干涉测量方法,研制了测量仪器,并对CCD像素格值和PZT进行了标定.该仪器以白光干涉理论为基础,利用空间频域算法计算白光干涉图零级条纹中心位置,根据零级条纹中心移动量来得到被测工件表面微观形貌.对被测工件表面进行了测试,试验结果表明:...     

一种基于光学技术的超声场测量方法研究

传统的水听器扫描法测量声场是一项冗繁、耗时的工程,光学三维条纹成像技术能在短时间内定量的测量声场.本文介绍了一种基于三维条纹成像技术的超声场检测方法,由CCD获得的声光衍射的断面强度图计算出光波经过声场后的相位分布图,对多幅不同角度相位分布图进行三维重建,由折射率和声压的关系可得出三维声压分布.通过实验结果和水听器得到的数据比较,两种结果有较好的一致性.     

不透明薄膜厚度的光干涉法测量以及台阶的影响

提出使用数字CCD拍摄光干涉条纹,使用图像处理软件进行灰度值扫描分析光干涉条纹的方法,对不透明薄膜进行光干涉法测厚.数字CCD和图像处理软件的结合使用能够最大限度的降低目测带来的误差,并且也避免了使用复杂的干涉条纹提取算法,可以方便、准确地对不透明薄膜进行光干涉法测厚.同时我们使用光干涉法和轮廓仪法对不同高度遮挡物形成的台阶进行了对比测量,分析了不同台阶边缘斜坡对于光干涉法测量结果的影响,指出在制备台阶时遮挡物的高度必须满足一定的条件,并且根据这个条件推导出在我们的磁控溅射设备中,遮挡物高度小于50 μm可以得到满足光干涉法测厚条件的台阶.     

时选窗技术在传声器自由场互易校准中的运用

实验室标准传声器的自由场互易校准是复现声压量值的一种基本方法,在测量过程中需要测试系统具有很高的信噪比.在空气声自由场声压基准装置中采用了步进正弦信号扫描和时间延迟谱技术测量传声器转移阻抗复频率响应,并采用IFFT得到脉冲响应,通过时域窗口消除反射,有效提高了信噪比,在体积较小的消声箱内完成了互易校准.     

全息剪切干涉法测量透镜几何象差

本文用全息双频光栅剪切干涉装置对透镜几何象差的测量进行实验研究。将象差光束中两剪切干涉光线的交点看成点源,提出了用经典杨氏干涉观点、由剪切条纹图确定这些交点的空间位置而直接得到几何象差的杨氏条纹分析法。对几个透镜的象差作了测量和分析;与设计理论值作比较,二者符合良好。     

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.     

长度计量基础知识讲座(三十四)

第三十四讲干涉显微镜1结构和工作原理干涉显微镜(以下简称仪器)主要由主体、工作台、干涉头、测微目镜、照明系统和摄影系统等部分组成。图1为常用的双光束干涉显微镜的结构形式。仪器基于等厚干涉测量平面度的原理,将同一光源发出的光线分为两束或多束,使其产生干涉。显微镜系统将干涉条纹放大,根据干涉条纹的间距     

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。     

Analysis of capillary interferometry for measuring refractive indices of minute samples

A method of measuring the refractive indices of minute samples by analyzing capillary interferometry is introduced. With the interference theory of light, the intensity distribution of an interference fringe pattern formed by a cylindrical tube of a capillary is obtained, and the influence of some parameters on the fringes are discussed. The measurement accuracy and its relative problems are analyzed.     

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.     

Fly Height Measurement Based on Phase Comparison Michelson Interferometry Using Low-Coherence Light Source

We present a method for measuring head fly height in hard disk drives using phase comparison Michelson interferometry (PCMI), which compares the phases of two interference fringe patterns formed respectively on the inner surface of a glass disk and the air-bearing surface of a fly head slider through the glass disk. To suppress interference noise and further enhance measurement accuracy, we adopted a low-coherence light source as an illumination source to replace a high-coherence laser. The captured fringe images enabled us to extract ridge lines much more accurately than with a laser. We compared our measurements in the sub-10 nm spacing range with calculations and found excellent agreement.     

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.     

Quasi-achromatic laser Doppler anemometry systems based on a diffractive beam splitter

We propose a new beam-splitter system that makes it possible to use nonstabilized laser diodes for laser Doppler anemometry (LDA) systems by making the system wavelength independent. The beam splitter consists of two linear diffraction gratings that produce two parallel beams with a beam spacing that is wavelength dependent. This ensures passive wavelength compensation for the fringe spacing in the measurement volume. One can choose the distance between the two parallel beams by changing the distance between the two gratings, whereas the distance to the measurement volume can be designed by choice of a condensing lens with the proper focal length. This means that the system can be designed to have a desired fringe spacing in the measurement volume. The gratings are implemented as surface-relief holograms in photoresist, which makes it possible to mass produce the beam-splitter system at low cost through replication of the structure. The method for passive wavelength compensation for the fringe spacing is demonstrated both theoretically and experimentally.     

基于近场测量法的水声换能器声场重建方法研究

为了提高对水声换能器声场分析的效率,开展了基于近场测量法的水声换能器的声场重建方法研究,首先将水声换能器的全息测量面近似为等效声源面,通过积分得到声场重建模型,然后利用自主研发的水下声场测量系统获得发射换能器全息测量面的复声压,实现对其声场的重建,最后比较不同全息测量面的重建结果和实测数据,并分析全息测量面的位置对重建结果的误差影响,得到了重建方法的有效测量区间。该声场重建方法可快速得到水声换能器的声场分布,并且准确可靠。     

Certification of specimens for checking profilographs and profilometers

Conclusions By studying the problems related to certifying specimens which have regular profiles and are intended for checking contact profilographs and profilometers of the M system it is possible to arrive at the following conclusions.In the case of the visual interference method for measuring heights, which is used for certifying specimens with a profile of a simple shape formed by straight-line segments, the measurement errors produced by superposing subjectively the sighting line of a reading device over an interference fringe are determined mainly by the interference field parameters (the visible width of an interference fringe and the luminance function in the contour-shaping area). Measurements with a minimum error correspond to visible fringe widths of 0.03–0.06 rad (under normal conditions).The angle between the profile elements can be measured by means of the interference method independently of the relative position of the reference plane when =0.Profilograms with an absolute and independent scale can be obtained for profiles of a complex shape by means of a photoelectric interference scanning system.In this system the profile elements' recording errors can be analyzed by means of the profile linear approximation method by representing the screen-emitted luminous flux in the form of a Fourier series of spatial frequencies.For the majority of the specimen's regular profiles the error which can be tolerated in practice for transmitting the shape of profile-approximating elements occurs when the ratio between the interference fringe width normal to the scanning trajectory and the size of the screen components is equal to ten. The raising of this ratio does not provide a substantial reduction of the error.Translated from Izmeritel'naya Tekhnika, No. 2, pp. 24–28, February, 1969.     

均匀活塞阵辐射声场研究

主要研究了均匀活塞阵的近-远场的辐射声场。首先利用点源声波干涉原理建立均匀点源活塞阵的辐射声场理论,进而推导均匀活塞阵的近-远场的辐射声场函数表达式,并采用Matlab软件仿真了近-远场的辐射声场,分析了近-远场的声场变化规律、声轴方向声压的变化规律和旁瓣级的变化规律。通过与实测的80 kHz均匀活塞阵换能器近-远场的辐射声场对比,表明了实测结果与仿真结果基本一致,验证了理论与测量方法的可行性,能够为实际测量工作提供指导。     

双通道传递函数法测量矢量水听器自噪声

针对矢量水听器自噪声测量时受环境干扰严重的问题,提出了利用双通道传递函数法测量矢量水听器的自噪声。给出了双通道传递函数法降低环境干扰的原理;并通过实验手段分析了利用该方法测量时,环境背景噪声条件及水听器布放距离等因素对测量结果的影响。研究结果表明,利用双通道传递函数法测量矢量水听器的自噪声,可以有效降低环境背景噪声影响,得到更加准确的结果。该方法为准确测量矢量水听器的自噪声提供了有效的手段,为矢量水听器在远程探测领域的实际工程应用提供了测量基础。     

双层插值NAH噪声源定位方法研究

针对近场声全息(near-fieldacousticholography,NAH)在实际测量环境下降低环境噪声的影响且保证全息面上声压重建精度的需求,基于空间面积分声压重建理论,在基于等效源法的近场声全息方法(near-field acoustic holography based on equivalent sour...