外差干涉仪中声光调制器特性对测量精度的影响

提出并论证了混合型声光调制器衍射光的衍射级次混叠特性, 它使衍射光强中存在着驱动频率的谐波项, 此外入射光束的漂移将引起衍射光的频率漂移。分析了在外差干涉仪中应用它们对测量精度的影响, 提出了消除这些因素影响的方法： 利用双声光调制器外差干涉, 并在干涉仪的内部提取测量的参考信号。用双声光调制器的外差干涉仪可以实现纳米测量。     

外并干涉仪中声光调制器特性对测量精度的影响

提出并论证了混合型声光调制器衍射光的笛射级次混叠特性,它使衍射光强中存在着驱动射频率的谐波项,此外入射光束的漂移将引起衍射光的频率漂移。分析了在外差干涉仪中应用它们对精度的影响,提出了消除这些因素影响的方法;利用双声光调制器外差干涉,并在干涉仪的内部提取测量的参考信号。用双声光调制器的外差干涉仪可以纳米测量。     

全视场外差长腔干涉测量技术

提出了一种适用于长焦光学镜片面形测量的新型激光干涉仪。利用全视场外差移相技术能有效抑制振动和大气等环境因素对长腔干涉测量的影响,采用Twyman-Green干涉仪结构,实现测量波面和参考波面的外差相干测量。搭建了实验验证系统,实验证明该方案能较好地抑制外界振动和大气湍流对测量精度的影响,实现了较高精度的长腔干涉测量,仪器的RMS(Root Mean Square)重复测量精度达到0.45‰λ。该技术可以作为长腔干涉测量的可选方案之一。     

纳米精度外差干涉仪非线性漂移的研究

在纳米精度外差干涉仪中，由于非线性温度漂移，成为外差干涉仪实现纳米精度测量的重要误差源。本文对差动干涉仪的理论分析得出如下的结论，干涉仪中除了测量光路和参考光路以外，还存在参考光误差分量和测量光误差分量的额外光路，从而引和了干涉混叠，产生非线性漂移：１／４波片的相位延迟量误差和安装是引入非线性漂移的主要因素，其影响程度是一阶的，提高波片对加工精度，并尽量减少其级数可降低非线性漂移。     

在线测量表面粗糙度的共光路激光外差干涉仪

一种新型的、用于在线测量表面粗糙度的激光外差干涉仪已研制完成。该仪器体积小（２５ｃｍ×２０ｃｍ×１０ｃｍ）、抗外界环境干扰能力强。仪器以稳频半导体激光器作为光源。共光路设计,使测量光和参考光沿同一路径入射到被测表面上。计大数和测小数周期相结合的外差信号处理方法,实现了大的动态测量范围和很高的测量分辩率。同时还采用了全反射临界角法进行自动聚焦。该仪器的纵向和横向分辨率分别为０．３９ｎｍ和０．７３μｍ;自动聚焦范围为±０．５ｍｍ,在焦点±２５μｍ范围内,聚焦精度为１μｍ;８０分钟内整机稳定性：３σ＝１．９５ｎｍ。     

激光干涉仪应用于无导轨测距的研究

本文提出了一种使用外差激光干涉仪实现无导轨测距的方法.该方法动态跟踪测量反射镜,使测量信号不中断,实现反射镜在一定范围内的非直线运动.这样,拥有双频激光干涉仪的用户,再添置一台比较简单的跟踪装置,即可用于无导轨测距,测量精度可远高于通用测距仪,为大型设备现场组装和安装提供了新方法.本文介绍了工作原理及实验情况.     

基于人工神经网络的大量程光纤实时距离干涉测量仪

提出了一种基于人工神经网络的全光纤化大量程实时距离干涉测量仪.采用双正弦相位调制方法,即通过同时调制半导体激光器的波长和干涉仪的光程差实现外差测量.为了扩大干涉仪的测量范围和消除输出信号中的交叉敏感,采用人工神经网络进行信号处理,把两路经过初步解调的干涉信号作为输入样本,物体距离的实际值作为输出样本,对神经网络进行训练,以使其具有良好的推广能力.实验结果表明神经网络的使用不仅扩大了距离的测量范围而且提高了测量精度.     

用于位移精密测量的光外差马赫-泽德干涉仪

本文介绍了我们研制的用于位移精密测量的光外差马赫－泽德干涉仪。由于在光路设计中采用了共光路的布置，共模抑制技术得以实现，环境干扰产生的噪声得到很好的消除，相位检测的稳定性和精度大大提高。使用该干涉仪测量了一台在光学相移器内ＰＺＴ微位移驱动装置的电压－位移关系。测量结果具有良好的线性和重复性，与预期相符。根据测量数据分析，该光外差干涉仪具有３ｎｍ的位移测量精度。     

一种基于光学倍乘原理的绝对距离干涉测量系统

介绍了一个基于光学倍乘原理的绝对距离干涉测量系统。系统包括两个干涉仪:采用半导体激光器作为光源的定位干涉仪和测量位移的外差干涉仪。介绍了光源的选择,系统的设计以及信号的采集和处理方案。采用这套绝对测量系统,可以实现长度为2m以内的绝对距离测量,定位精度可以达到±0.5μm。     

双平衡式相干接收原理及其在外差干涉仪中的应用研究

利用琼斯矩阵理论推导了光学双平衡式相干接收的原理,得到了具有正交相关性的包含全部光学信息的IQ信号,给出了基于IQ正交信号解调待测光信号信息的信号处理算法.基于该原理设计了一种高速微机电系统扫描式激光外差干涉仪,得到了待测玻璃的厚度信息分布图.该干涉仪的波前相位差提取准确度可高达0.01 rad、测量速度可达40 frame/s、最大测量直径可达到300mm,在实时光学检测方面有广阔的应用价值.     

共光路外差干涉法精密测量光学表面

报道了光学外差法测量表面起伏精度及横向分辨精度达到０．１１ｎｍ及４μｍ。本文采用的是完全共光路外差干涉系统，阐述了它的原理、构造及噪声的影响，并将测量结果与其它商品仪器测量结果作了比较。     

Micro-Gal laser absolute gravimeter based on high precision heterodyne interferometer

A micro-Gal absolute gravimeter based on high-precision and high-stability heterodyne interferometer is presented. The distance measuring technology of the gravimeter is studied in detail. The experimental results of distance measuring for a free-falling motion show that the high-precision heterodyne interferometer described in this paper can meet the demand of a micro-Gal absolute gravimeter with relative uncertainty of 6.4 × 10-9. Moreover, the heterodyne interferometer is more stable than the Mach-Zehnder interferometer (MZI) which is widely used in present absolute gravimeters.     

激光外差干涉快速超精密测量模型研究

为了精确地描述激光外差干涉在快速超精密测量中的位移测量．建立了激光外差干涉快速超精密测量模型。传统外差干涉测量模型采用舍去高阶误差的方法,便于分析与快速计算,但存快速纳米精度测量中,高阶误差已经影响到测量精度．根据多普勒频移公式,通过分析激光外差干涉的测量原理．在已有的激光干涉测量模型上增加了u^2/c的积分项．相当于将传统测量模型进行了高阶误差补偿。通过理论分析可知,当最高测量速度为1m/s,运行位移为3m时,该测量模型能够减小约18nm的测量误差,解决了传统测量模型存存的残余误差累计问题,从而为激光外差干涉在快速超精密测量领域的应用提供了一种理论依据。     

Heterodyne interferometer scheme using a double pass in an acousto-optic modulator

We introduce a heterodyne interferometer scheme utilizing the double-pass arrangement of the deflected beams of an acousto-optic modulator. To prove our new idea, the interferometer has been applied for measuring small amplitude vibrations. The output intermediate frequency signal from the interferometer is processed by using an I/Q demodulator. In theory, it can provide the quantum noise limited sensitivity, whereas, in our present Letter, the sensitivity of the phase measurement is limited by the resolution of the 16?bit A/D converter used for processing the I/Q signals. Details of our interferometer scheme are discussed.     

Linearization methods of laser interferometers for pico/nano positioning stages

Presented work introduces methods for improving linearity of a heterodyne laser interferometer system. The heterodyne configuration exhibits high potential in demanding applications, like pico/nano positioning. Those applications require superior accuracy, more difficult to obtain in a homodyne configuration of the laser interferometer. The homodyne setup is more susceptible to external light, variation of DC offset and higher noises, especially the 1/f noise. Those issues are filtered out in the heterodyne configuration. The main disadvantage of heterodyne setup are higher measurement nonlinearities. In this paper there are first introduced sources of nonlinearities and their impact on the overall accuracy. According to those findings there are proposed techniques to eliminate error caused by parasite beams, i.e. nonlinearities. Presented method is based on digital signal processing and is reliable and easy to use. In the shown approach the nonlinearities correction is completely automatic. Such system is applicable for X/Y positioning stages. Presented configuration of the laser interferometer is able to track the displacement with 100 pm resolution up to 7 m/s of translation velocity. The resolution can be improved to 10 pm by limitation of maximal velocity. In the paper there is confirmed that errors caused by nonlinearities are in range of ±0.6 nm. Achieved accuracy is comparable to capacitance gauges with presented laser interferometer having much better dynamic range.     

高精度表面粗糙度外差干涉仪信号处理系统的研制

针对用于磨床加工的光外差表面粗糙度在线干涉测量仪，文中介绍了整机的信号处理系统，着重讨论了两项关键技术。即宽动态范围测量信号的自动控制和高精度动态相位测量，系统的测量精度达２．６°（相当于３．２ｎｍ），允许测量中最大多普勒频移±２０ｋＨｚ（对应高度的变化率±８．７５×１０－３ｍ／ｓ），完全满足磨床加工中表面粗糙度在线测量的要求。现场测试证实了这一点，这对于精加工、超精加工表面粗糙度的在线质量控制、提高加工精度等非常重要。     

Absolute distance measurement by using modified dual-wavelength heterodyne Michelson interferometer

This study proposes a modified dual-wavelength heterodyne Michelson interferometer for measuring the absolute distance that can avoid the influence of wavelength drifts. This modified interferometer consists of two conventional Michelson interferometers. A standard plate is introduced in one arm of one Michelson interferometer. The phase differences of p- and s- polarization test lights in the two interferometers can be measured accurately by dual-wavelength heterodyne interferometry. Hence, the absolute distance can be determined by substituting the phase differences into special derived equations. Meanwhile, the test lights suffer from the same wavelength drift effect. Therefore, the negative effect caused by the drift can be offset, and the measurement stability can be significantly increased. The feasibility of this method was demonstrated with a measurement resolution of about 1.36 μm. Additionally, this method has a simple structure, easy operation and rapid measurement.