移相式干涉仪在锥体棱镜角度测试中的应用

为了实时、高精度地测试光学零件，对移相式数字波面干涉仪在锥体棱镜角度测试中的应用进行了研究。通过锥体棱镜二面角偏差计算方法得到了二面角偏差和干涉波面之间的关系，分析了干涉波面的形状与锥体棱镜综合误差的关系，编写了锥体棱镜角度和综合误差测试程序，并且在移相式数字波面干涉仪和ZYGO干涉仪上分别对锥体棱镜进行测试，给出了2者的比较测试结果。结果表明，移相式数字波面干涉仪测量锥体棱镜二面角偏差的误差在0.3″范围内，RMS值的测量误差在λ/50内；提出的方法可实现检测过程的自动化。     

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.     

对热释电摄像机调制方法的研究

本文主要分析了用于红外干涉测试中的热释电摄像机的工作原理及其调制特性，比较了几种调制方式的优缺点，最后提出了热释电成像的移相调制法，考虑了优选调制频率对测试结果的影响，并给出实测结果。     

Suppression of Multiple-Beam Interference Noise in Testing an Optical-Parallel Plate by Wavelength-Scanning Interferometry

Measurements of optical parallel plates in a Fizeau interferometer lead to problems from multiple-beam interference noise unless the back surface of the plate has an additional treatment to prevent its reflection from reaching the detector. Such internal-reflection noise can be separated from the fundamental interference signal by its modulation frequency in a wavelength-scanning interferometer. However, to completely eliminate the noise, the air-gap distance between the testing and reference surfaces of the interferometer must be adjusted to a specific value, depending on the thickness and refractive index of the plate. This adjustment requires an undesirable change in the air gap, which is related to the phase modulation rate of the interferometer, and also requires additional information regarding the testing plate, which makes the measurement laborious. We show that if we add new symmetries to the sampling functions of the phase measuring algorithm, we can obtain significantly greater tolerance for the air-gap error. A new 19-sample algorithm allows a tolerance of ±23% while keeping the systematic errors at less than λ/200. The periodicity of the new algorithm and an integrating bucket technique also provide more options for the thickness of the testing plate, which guarantees an air-gap distance more independent of this thickness.     

Analysis on 3D object measurement based on fringe projection

A coordinate measuring method is presented, which is specially devised to perform the measurement of coordinates with projected fringe techniques of projectors in three dimensions. The system is composed of two parts: one is a target which can move freely in three dimensions, and the other is a stationary two-dimensional array of photodetectors. The mini-projector is tied to the target, and the projected fringe is monitored by the photodetectors. The phase of the photodetectors can be precisely measured with the phase-shifting algorithm, so that, the xyz location of the target can be determined with the geometric model of multilateration using the method of optimization. In this paper, the measuring principle, iterative method, computer simulation and preliminary results are given. The phase-shifting technique has the advantages of high accuracy and noise endurance. The method will provide the basis for follow-up iterative optimization calculation. The experimental results prove that the proposed coordinate measuring method is of high precision.     

Parallel two-step phase-shifting microscopic interferometry based on a cube beamsplitter

Parallel two-step phase-shifting interferometry for microscopy is presented, and the recording condition for generalized two-step phase-shifting interferometry is discussed. A 45° tilted cube beamsplitter enables to replicate the orthogonally linear polarized object and reference waves into two parallel beams, respectively. As a consequence, two interferograms with quadrature phase shift are obtained along the two beams, and phase reconstructed with an improved algorithm. To reconstruct the phase distribution from the two-step phase-shifting interferograms, a certain recording condition should be satisfied. However, the recording condition has not ever been discussed before. In this paper, the recording condition for the two-step phase-shifting interferometry is derived and that is: the intensity of reference wave should be no less than two times object wave intensity.     

基于二维傅里叶变换的单帧干涉图相位提取方法

针对大口径光学元件干涉测试过程中,测试装置和干涉腔长较大,气流扰动和环境振动对移相测试过程产生影响等问题,采用一种基于二维傅里叶变换的单帧干涉图处理方法,只需要对一幅空间载频干涉条纹图进行处理即可获得待测相位,具有抗振测试的优点。对该方法的基本原理和算法过程进行分析,并对近红外大口径移相平面干涉仪中600 mm口径的光学平晶进行了面形测试。实验结果表明:采用该方法所得波面峰谷值(PV)为0.112,波面均方根值(RMS)为0.014,与移相算法所得波面数据相比,波面峰谷值偏差不到(1/500);波面均方根值(RMS) 偏差几乎为零。     

偏转平台剪切电子散斑干涉相移技术研究

在沃拉斯顿棱镜作为剪切器件的传统剪切散斑干涉术中,由于错位的二物光束同光路传播,很难通过将它们分开来引入附加相位的方法实现相移。本文提出的偏转平台法是利用平台上物体的偏转来引入附加相位的,从而可以实现剪切电子散斑干涉的相移。理论分析证明,物体的偏转可以引入稳定、线性的附加相位,并给出了物体偏转角度与附加相位之间的关系式;利用周边固定、中心加载圆盘进行了典型实验,给出了实验结果,证明偏转平台相移技术能够有效地从干涉条纹中提取位移导数信息。     

Self-calibration of a phase-shifting adapter for Fizeau interferometers

Phase-shifting interferometers with three piezoelectric transducers (PZTs) on their phase-shifting adapter (PSA) are widely used in precision measurement. The guarantee of the PSA to stretch as a flat is very important to the accuracy of the measurement. In this paper, we propose a systematic self-calibration method to calibrate the different displacements of the PZTs so that the PSA can be moved evenly as a flat. The proposed method uses only the interference patterns to calibrate the three PZTs and information about the exact position of the PZTs and the instrument parameters of the interferometer are not required. Experimental results show that, after calibration by the proposed method, the deviation of the measured phase shift error could be reduced about 43.1 times from 3.492 to 0.081°.     

两步广义相移干涉术的光学实验验证

提出了一种基于两步广义相移干涉术的波前再现技术以及基于衍射场统计特性的未知相移值提取算法,并且进行了光学实验验证.该方法中可仅利用两幅干涉图及一次不需精确预设的未知相移,参照物光光强和参考光光强,即可通过计算提取真实的相移量,进而恢复出物波波前复振幅,而无需借助傅里叶谱分析或数字滤波等操作.在光学实验中,对借助于空间光调制器（SLM）的间接输入和三维漫反射物体直接输入两种情况进行了详细地研究,得到的光学实验结果验证了所提方案的有效性和可行性. 关键词： 信息光学 相移干涉术 波前再现 数字图像处理