A Reference Optical System of Laser Doppler Longitudinal Displacement Measurement

In this paper, a new reference optical system is put forward to achieve longitudinal displacement measurement. An optical grating is used for frequency mixing and getting high SNR signals in the measurement. Conditions and methods for getting Doppler beat signals are presented.The experiments indicate that this optical syetem can be used to measure the longitudinal displacement with high accuracy.     

Study on a reference optical system applied to the outline loss measurement of complicated three-dimension object

In this paper, laser Doppler reference optical technique is studied, and an optical system with high resolving power which is applied to longitudinal displacement measurement of complicated 3-D object is brought forward. Structure of the measuring optical head is designed reasonably. The experiments prove that the new-type reference optical system can achieve the outline loss measurement of object with the relative error of 0.3%.     

一种可用于离面位移测量的光路的优化设计

为了实现对复杂三维物体表面轮廓、小空间内物体的纵向位移或振动等测量，有必要研制高分辨力、非接触的光学检测系统。由于激光多普勒技术具有动态响应快、线性度好、非接触、测量精度高等特点而优先被用于复杂三维物体离面位移的测量。但是物体表面散射光的多普勒信号非常微弱，因此解决信号的强度、信噪比则是实现测量的关键。研究了激光多普勒技术及散射光相位的无规变化的统计规律，设计出一种空间分辨力很高的参考光路，将它用于固体离面位移测量效果很好，其相对误差为0．3％。     

光纤外差干涉位移传感器性能的提高

利用半导体激光器 (LD)、光隔离器、光纤定向耦合器、自聚焦透镜等组成双路光纤斐索型干涉仪。采用三角波电流调制 ,上、下边沿拍频信号差动鉴相的方法 ,提高了测量灵敏度和位移响应速度 ,增大了测量范围 ;利用辅助干涉仪检测系统的相位漂移 ,并对LD发光波长进行反馈控制 ,提高了系统的稳定性 ,实现了大测量范围、高分辨率、高精度位移测量。     

双目立体视觉技术在结构试验中的应用

传统的动态位移测量方法属于接触式测量,常用应变式位移计直接测量结构变形,其测量精度往往取决于位移计安装情况,且测量的电信号容易受到试验环境的影响。随着光学测量技术的不断发展,基于双目立体视觉和数字图像处理技术的光学测量方法已开始应用于位移测量。为了解决传统动态位移测量的精度问题和环境对信号的干扰问题,将双目立体视觉技术应用到三层钢框架结构的振动台试验中,对结构在地震作用下的位移进行测量。研究结果表明:从位移时程和位移偏差率两方面同传统测量方法进行对比分析,光学测量方法减少了2.0 s~3.5 s的相对滞后时间,增强数据可靠性;位移偏差率最大为7.03%,最小为0.02%,均在测量误差允许范围之内,验证了光学测量位移方法在结构抗震试验中的可行性及优越性。     

面内位移测量的激光多普勒信号研究

在利用激光多普勒效应进行远距离处固体面内位移测量时，散射光的多普勒信号强度、信噪比及信号质量是位移测量的极重要参量，它们直接影响位移测量的距离和精度。为此研究了激光多普勒差动方法、锁相放大、数字滤波等技术，设计出能获得最好结果的差动光路以及高灵敏度、高Q值的锁相放大器和能重构丢失信号的同态滤波系统等，实现了50m处固体面内位移测量，其最大相对误差可以达到1.5％。     

基于相位凝固技术的激光反馈干涉术

针对激光反馈干涉术,提出基于相位凝固技术的调制解调方法,用以提高位移测量的分辨率,并设计了利用相位调制器进行调制的位移测量系统.利用调制器进行外腔相位调制,采集调制相位相对固定的干涉光信号,通过解调重构得到被测的位移信息.进行了信号调制、采样、重构技术的研究以及误差分析,并通过仿真验证了方法的可行性.结果表明,采用5点相位凝固采样技术,测量准确度可以达到λ/20.此方法可提高激光反馈干涉术的测量分辨率,实现信号实时采集处理,可用于位移的实时测量.     

飞秒光频梳的任意长绝对测距

高精度测距在工业、航空航天、科学研究等方面都具有重要应用, 而不断发展的激光测距技术始终处于前沿研究领域. 本文研究飞秒光频梳绝对测距技术, 拓展光梳在长度测量领域的应用. 在利用脉冲激光进行任意绝对长度测量中常用到飞行时间法, 然而其测量分辨力受限于电子器件的带宽, 仅为毫米量级. 为克服这一缺点, 本文研究了光梳多脉冲序列之间的时间相干性, 结合多脉冲序列干涉法和飞行时间法提出了任意长绝对测距的方法, 搭建了基于改进型Michelson干涉原理的任意绝对测长系统, 通过同时测量多脉冲序列的一阶和二阶互相关信号, 可以分别计算出飞行时间的时间差, 即可得到被测距离. 利用光梳作为光源进行了0.6m的绝对测距实验, 将测量结果与高精度激光位移传感器的测量值进行比较, 实验结果表明本系统具有良好的测量线性度, 并且测距精度可达±0.5μm. 关键词： 飞秒光频梳 任意长绝对测距 飞行时间法 多脉冲序列干涉法     

A novel interferometric vibration measurement sensor with quadrature detection based on 1/8 wave plate

In-phase and quadrature-phase (I/Q) signals often need to be formed in the laser interferometric vibration measurement technique. To avoid the disadvantages of traditional I/Q signals forming methods such as effect of piezoelectric ceramic (PZT) for generating high frequency carrier, or optical configuration with complicated structure, a novel interferometric vibration measurement sensor with quadrature detection is proposed. The sensor utilizes simple optical configuration which contains 1/8 wave plate to generate two I/Q signals, then the signals were processed by arctangent algorithm which is compiled by Labview software through data acquisition card. Theoretical analysis and experimental Lissajous figures synthesis prove the phase orthogonality of the two signals. The experimental results indicate that the system can measure the vibration displacement accurately.     

切线位移法测量微小角度偏转

叙述了将光电传感器的光轴相对固联于地理坐标系的转轴作切线运动并利用其切线位移模拟小角度偏转的方法。根据两轴初始零位对准值及切线位移量,由光电传感器的输出和所对应的角度偏移关系,获取光电传感器光轴的微小角度偏转量。该方法是一种简单有效的小角度偏移光电检测方法,可实现对微小角度偏移量的精密测量和实时读取,角度测量范围:±15°;测角精度:1″。     

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。     

Design of differential optical system of in-plane remote displacement measurement

In this paper, an optical system for in-plane remote displacement measurement is brought forward. The remarkable characteristic of this optical system is to use a big aperture lens to focus the waists of two Gauss beams on a scatter which have been expanded and collimated, so good laser Doppler signals and high measurement accuracy are achieved. The experiments prove that the measurement system consisting of this optical system, a lock-in amplifier and a digital filter can be used to measure the in-plane displacement of scatters in distance of 50 m with the relative accuracy of 1%.     

Non-incremental interferometric displacement measurement using a laser Doppler sensor with phase coding

The inspection of fast rotating objects with rough surfaces is an important task in the emerging field of process control. However, this is challenging since fast and non-contact inspection techniques with a measurement uncertainty in the nanometer range are often required. We present a novel optical sensor allowing non-incremental interferometric displacement measurement of moving solid state objects with rough surfaces. It features three wavelength coded interference fringe systems which are superposed slightly tilted. The displacement is determined by evaluating the phase shift between the resulting scattered light signals. Experimentally, a measurement uncertainty of 660 nm was obtained. This displacement uncertainty is independent of the lateral object velocity in principle. Due to this unique feature, the sensor can be utilized advantageously for precise displacement and vibration measurements of high speed objects as demonstrated by vibration measurements at a turbo pump shaft rotating with 48 000 rpm.     

Heterodyne interferometer for displacement measurement with amplitude quadrature and noise suppression

The high precision displacement measurement in nanoscale is crucial to many applications. We present a heterodyne interferometry with differential phase to amplitude conversion scheme for displacement measurement in nanoscale. In this approach, the differential phase introduced by the displacement is converted into the amplitudes of heterodyne signals in quadrature. Meanwhile, the heterodyne signals in phase quadrature are also achieved so that the displacement can be determined from the amplitude ratio of the quadrature signals, and the direction of displacement can be determined from the phase quadrature. Since the differential phase to quadrature amplitude conversion is achieved through the optical addition and subtraction by polarization tuning, which are based on differential detection concept. Thus the proposed method benefits from the features of differential detection with common phase noise and correlated amplitude noise rejection and that of quadrature detection with real time and wide dynamic range of phase measurement. To demonstrate the capability of proposed method in differential phase measurement, we measure the displacement drove by a commercially available PZT pusher and found close agreement between the experiment and the theory. The experimental evidence of noise suppression is also found with spectral measurements, which demonstrates the resolution of displacement measurement at 60 pm and minimum detectable differential phase of 5.6 × 10⁻⁶ rad/ over 50 kHz.     

Design and evaluation of a Blu-ray pickup head system for determining the tilt angle and displacement of the test plane

We present an optical system design for determining the tilt angle and displacement of the test plane. The proposed optical system consists of a Blu-ray pickup head and a pigtailed laser diode with a uniform Gaussian beam. The optical system is evaluated by two optical design software packages, Code V and LightTools. A quadrant detector is used to detect the relative relationship of the V_A, V_B, V_C and V_D output signals, which can be used to measure the tilt angle and displacement on the test plane. Both the tilt angle and displacement on the test plane can be determined from the change in the beam shape on the quadrant detector. The proposed system can generate a circular uniform beam shape to reduce the misjudgment and to enhance the measurement accuracy. Various simulation cases are presented in detail to show the feasibility of the proposed system.     

Measurement of the off-plane displacement of carbon steel corrosion with twin-object-beam electronic speckle interferometry

In this paper, twin-object-beam electronic speckle interferometry is used to study the longitudinal corrosion of carbon steel. The displacement expression of this technique is deduced and optical fibers are used to reduce the influence of the optical system and improve the quality of speckle pattern. Twin-object-beam electronic speckle interferometry cannot only quantitatively cipher out off-plane displacement as a result of corrosion, but also estimate the change of corrosion speed.     

CCD位移传感器结构参量计算方法

推导了CCD位移传感器的计算公式,给出了一种位移传感器结构参量的数值逼近计算方法,实验结果表明,利用该方法确定CCD位移传感器的结构参量,可提高测量精度.     

二维复用半导体激光器线性调频光纤位移传感器的研究

利用半导体激光器线性调频外差干涉原理和频域多路复用原理,研究了光纤位移传感器多路复用技术,制作了两路复用光纤位移传感器,研究和解决了多路复用时信号串话问题.实验证明,各路之间串话引起的误差小于±0.02μm,每路测量误差小于±0.05μm.     

光纤传感器位移和转速测量研究

介绍光纤传感器的测量原理,并对位移和转速测量进行研究,利用matlab软件对位移测量结果进行曲线拟合,且将光纤传感器和电涡流传感器的转速测量结果进行比较,最后得出利用光纤传感器进行测量具有电路结构简单、精度高、光路弯曲等优点。