用于微位移测量的笔束激光干涉仪

介绍了一种基于空间干涉原理的亚微米零差干涉位移测量方法。该方法是对笔束激光干涉仪在微位移测量领域的应用 ,干涉仪的测量精度不受光束波前畸变等光源噪声的影响。给出了干涉仪主要结构参数的选取原则 ;构建了用于微位移测量的笔束激光干涉仪实验系统。实验结果表明 ,该系统具有纳米测量分辨率。     

透明软质薄膜的表面形貌测量

为了实现光刻胶表面形貌的广域、高精度测量,对新一代测量理论及测量方法进行了研究。首先分析了被测物件的特性,根据其柔软、透明的特征提出应用光干涉法和机械探针相结合的方法进行测量,同时阐明了使用此方法进行表面形貌测量的优点,并据此原理搭建了光学多探针表面形貌测量装置,光学测量部分采用白光干涉计,探针部分采用拥有8只球型探头的多点悬臂测量探针。然后应用此装置对标准刻槽试件和半透明光造型薄膜试件进行了测量。测量52 nm的标准刻槽试件时得到了测量误差小于2%,标准偏差小于1 nm的结果,表明本装置可以达到高精度测量表面形貌的目的。通过测量高约400 nm的树脂材料证实了此装置可以克服多重反射的影响测量透明薄膜的表面形貌。     

Surface-profile measurement by means of a polarization Sagnac interferometer with parallel optical feedback

We describe a novel feedback interferometer for real-time, unambiguous measurement of surface profiles that consists of a polarization Sagnac interferometer and an optically addressed phase-only spatial light modulator. In this system the output intensity from the Sagnac interferometer is optically fed back to the phase modulator placed in one arm of the interferometer, which produces a sawtooth fringe intensity profile (instead of the conventional cosinusoidal one) that is directly and unambiguously related to the surface profile. Preliminary experimental results demonstrate the feasibility of applying this system to surface-profile measurement.     

静力水准系统用于基准高差测量的研究

为了拓展静力水准系统（HLS）在粒子加速器准直测量工作中的应用,开展了针对HLS系统用于多点间基于水平面的基准高差测量的实现方法的研究。基于传感器工作原理,设计并搭建了一套由双频激光干涉仪、高精度位移平台、HLS传感器等组成的比对系统,利用该系统控制多传感器在同一坐标系下观测同一液位。通过比对获得多传感器间基于底部坐标系的零位高度差,实现了多个传感器坐标系间相对于水平面的高差值测量,并验证了高差测量精度优于5 μm。除此之外,通过在HLS传感器上方安装靶座,使用三坐标测量机(CMM)严格标定各传感器电极板至靶球球心的距离,实现了多靶球球心位置基于水平面的高差值测量,并验证了其测量精度优于30 μm。     

Fiber-optic Based Scanning Confocal Microscopic Interferometer for the Measurement of Surface Topography

A fiber-optic based scanning confocal microscopic interferometer with digital feedback is developed for the precise measurement of the surface topography on a large-scale object of complex shape with steep surface slopes. Theoretical analysis on interference formation demonstrates the confocal characteristic of the proposed interferometer along its measurement path. Experimental results confirm the spatial resolution of the measuring system to be within 1 μm and the measurement accuracy to be better than 5 nm.     

Fiber-optic Based Scanning Confocal Microscopic Interferometer for the Measurement of Surface Topography

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Surface profilometry by wavelength scanning Fizeau interferometer

We have applied wavelength scanning interferometry to Fizeau interferometer for surface profilometry. This interferometer is free from ambiguity of the sign in the measurement result. It is more compact in setup than the Michelson interferometer used previously. Experimental results from a step and a dip on a mirror surface are shown. In the focal depth of imaging system, we could measure a mirror surface with less than standard deviations of 20 μm including quantization error in frequency analysis. We also could measure the surface shape of a coin. Origins of the noises appearing in the results are also discussed.     

Modified polarization point diffraction interferometer with extended measurable NA for spherical surface testing

The small pinhole of point diffraction interferometer based on pinhole-point diffraction places ultra-high requirement on both the adjustment of testing system and performance of CCD camera. Besides, poor fringe contrast due to the low reflectivity of test spherical surface would limit the measurement precision in the processing of fringe pattern. A modified polarization point diffraction interferometer with extended measurable numerical aperture (NA) is presented for testing the spherical surfaces with low reflectivity. Measurement error factors as well as the corresponding calibration procedure are introduced in detail. Comparing with the results of Zygo interferometer, measurement accuracy with root-mean-square (RMS) value about 0.0026λ and peak-to-valley (PV) 0.0134λ is achieved. The system has good measurement repeatability, and the standard deviation of measurement results RMS better than 0.0010λ is obtained. The proposed interferometer reduces the difficulty in the adjustment of the system and provides a feasible way for testing the surfaces with low reflectivity and high NA.     

一种超快时间分辨速度干涉仪的设计和理论研究

在单发、超快时间分辨的测量技术中,线性啁啾脉冲和光谱仪的结合使用是一种常见方法.本文以成像型光谱仪为记录系统,利用线性啁啾脉冲的频-时对应关系,设计了一种应用于自由面速度超快测量的速度干涉仪.理论研究了其工作原理和适用范围,该速度干涉仪可以实现皮秒量级的时间分辨,且速度灵敏度可调、易调,大大拓宽了速度干涉仪的应用范围.数值模拟了系统的测速过程,结果表明,重建速度信号与给定物体速度符合得很好,进一步验证了系统的可行性.     

Noncontact Measurement of Surface Topography by Mirau Interferometer

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透过检测中的准直镜精度容限

在干涉检验过程中,被检元件的面形误差检测精度受到干涉仪系统结构的影响,从而降低测量结果的可靠性。为了得到较高的检测精度,必须对检测系统进行分析,建立测量误差和系统结构的关联度。根据菲涅耳衍射近似理论,就菲佐干涉仪中的准直镜和标准镜面形误差对透过检测的影响进行了研究。通过对波前相位传递情况的分析,得出波前误差和系统结构参量的相关性,去除空腔系统误差,优化结构参量,并建立准直镜误差容限表达式。经计算得出,当被检面形变误差为0.2λ时,测试误差可以达到0.02λ,而对准直镜的面形误差要求只需0.8λ。     

数字式激光平面干涉仪校准规范介绍

数字式激光平面干涉仪是用于测量光学元件面形和无焦光学系统波像差的光学仪器。为了统一数字式激光平面干涉仪测量量值，保证其测量结果的准确性和溯源性，编写数字式激光平面干涉仪校准规范。简要介绍了数字式激光平面干涉仪校准规范的构成，被校仪器的技术指标和校准方法等。     

液面基准法标定干涉仪系统误差

为消除干涉仪标准参考面的误差,保证其测量准确度,本文采用液面基准法建立光学平面基准对仪器的系统误差进行标定.首先建立弯曲静液面动力学方程从理论上分析润湿效应对液面平面度的影响,并结合实验分析气流、温度、震动等环境因素对液面稳定性的影响,讨论波面稳定性评价指标,给予实验验证.最后用建立的大液面基准对干涉仪系统误差进行标定,给出标定结果.     

光纤Fizeau干涉仪的声发射检测研究

验证了一种基于光纤Fizeau干涉仪的声发射传感器,可用于固体表面传播的超声波的检测.这种传感器的特点是能够精确地检测由固体表面传播的超声波产生的微弱振动.当超声波信号通过光纤传感器到达探测器时,干涉仪的输出光强度受到了超声信号的调制.通过检测干涉仪的输出光强度并利用Fourier变换,测得了超声信号的振幅和频率.对传感系统的相位调制特性进行了仿真,并对实验结果进行了分析.     

Design and experimental verification of novel six-degree-of freedom geometric error measurement system for linear stage

In this study, a novel and simple measurement system for simultaneously measuring the geometric errors in six-degree-of-freedom (6-DOF) for a moving linear stage of a machine tool is designed and validated. Compared to laser interferometer and laser Doppler systems, this new measurement system is less expensive and capable of multiple functions. The proposed measurement system comprises an optics module, composed of two reflectors and two cubic beam splitters; a sensing module, composed of three two-dimensional position sensitive detectors (PSDs); and a helium-neon (He-Ne) laser. Using skew-ray tracing and a first-order Taylor series expansion, the 6-DOF geometric errors of the moving linear stage, which include translation and rotation errors, are analyzed. A laboratory prototype system is built to verify the effectiveness and accuracy of the proposed measurement system. The experimental results show that the displacement uncertainty and the angular uncertainty of the proposed measurement system are less than 1.2 µm and 0.4″, respectively. Compared with the Renishaw laser interferometer XL-80 laser system, the translational accuracy and the rotational accuracy of the proposed measurement system are less than ±1 µm and ±0.2″, respectively, when the linear stage travels 6 mm.     

Comparison between a white-light interferometer and a tactile formtester for the measurement of long inner cylindrical surfaces

Shape measurements of engineering surfaces are an interesting and important application for white-light interferometry (WLI). Due to some factors such as: (a) the high-processing speed, (b) the ability to measure a huge quantity of points of the evaluated surface, and (c) the non-contacting nature; WLI has become a valuable tool for practical applications. This paper shows the achieved comparison between a modified white-light interferometer and an established measurement system, namely a formtester with a tactile spherical stylus sensor, which is the most commonly used instrument in the industry. Furthermore, this paper shows that the combination between the modified white-light interferometer and an adequate measurement and processing strategy has enabled to obtain a good agreement between optical and tactile measurements of long inner cylindrical surfaces. A cloud of points (COP) measured with the modified white-light interferometer has presented a standard deviation of about 0.3 μm when it was compared with formtester measurement of the same parts.     

Introduction of the Impulse Response Function in Common-Path Interferometers with Fourier Plane Filters

In the present paper it will be shown how the introduction of a Fourier plane filter can create various types of common-path interferometers for measuring changes in surface tilt or curvature of an object surface. This is obtained by placing a holographic optical element in the Fourier plane of a 4-f optical system. The interferometers are analysed by using the paraxial approximation of the Huygens-Fresnel integral formalism, and the interferometer functions are given by a novel formalism using impulse response functions. Based on this technique, an interferometer for measuring dedicated changes in surface deflection is presented. This interferometer is insensitive to rigid surface rotations and displacements. The interferometer can be embedded in systems based on single point measurement of a time dependent deflection, i.e. vibrometers, as well as in full-field measurements such as electronic speckle interferometers.This paper was originally presented at the 2001 International Conference (2nd Joint OSJ-SPIE Conference) on Optical Engineering for Sensing and Nanotechnology, ICOSN 2001 which was held June 6-8, 2001 at the Pacifico-Yokohama Conference Center, Yokohama, Japan.     

Measurement of in-plane motions and rotations using a simple electronic speckle pattern interferometer

We describe the construction and operation of a simple electronic speckle pattern interferometer which is sensitive to in-plane motions and rotations. The interferometer is extremely simple and easy to use. It uses a commercial digital still camera for image acquisition, and a personal computer for image storage and analysis. The interferometer was used to measure very small in-plane rotations of a rough surface, and the results were found to be in good agreement with the expected values. We propose to use this system as an instrument for the measurement of small-angle rotations.     

Absolute surface form measurement of flat optics based on oblique incidence method

In this Letter, a test method based on oblique incidence is practically implemented in the interferometric measurement process. Three sets of wavefront data are achieved through cavity interference measurement with a Fizeau interferometer and one oblique incidence measurement. An iterative algorithm is applied to retrieve the absolute surface shape of the test flat. By adding two sets of measurements, the absolute surface error of the interferometer's reference flat can be obtained. The new method can not only calibrate the reference flat error of interferometer, but also provide the absolute measurement method for high precision optical components applied in high power laser systems.     

Fiber interferometer for simultaneous multiwavelength phase measurement with a broadband femtosecond laser

We present a fiber interferometer for the simultaneous measurement of phase at multiple wavelengths from a single broadband femtosecond laser. Narrow-bandwidth fiber Bragg gratings isolate a particular frequency from the broad-bandwidth laser pulse produced. The multiwavelength phase data permit the unambiguous measurement range to be significantly increased compared with the wavelengths used in the interferometer. Preliminary experimental results are presented for a two-frequency sensor with an absolute range of 0.13 mm and associated dynamic range of 43,000:1.