Janus配置的激光多普勒测速仪的陆用组合导航（英文）

为了抑制车辆颠簸、倾角变化对传统激光多普勒测速仪的影响,设计了基于Janus配置的分光再利用结构激光多普勒测速仪,该测速仪由两个激光多普勒测速仪子系统镜像安装而成,可补偿倾角变化对速度测量的影响,因此对倾角变化不敏感.车载实验结果表明该测速仪的测速相对误差为0.3%,在55.6km的行程中组合导航的最大位置误差为5.8m.该结构激光多普勒测速仪能够抑制车辆颠簸、倾角变化对速度测量的影响,提高组合导航定位精度,更适合陆用组合导航.     

激光多普勒自主测速仪天线安装误差对测速精度的影响

为了减小激光多普勒自主测速仪天线安装误差引起的测速误差,以多普勒频移原理为基础,通过旋转矩阵的复合变换推导出测速误差与安装误差间的函数关系,分析了三个安装误差角对三维测速精度的影响,并对旋转矩阵采用Bursa模型线性化后在整体最小二乘准则下给出安装误差角的最优估计,从而实现测速误差的补偿。仿真结果表明:测速误差随速度的增大而增大,影响纵向、横向测速精度的主要因素是偏航角,影响垂向测速精度的主要因素是纵倾角,补偿后三维测速误差显著减小。     

相关时延及频谱不对称对声学多普勒测速偏差影响

研究了复协方差频移估计测速下相关时延及接收信号频谱幅值不对称对声学多普勒测速偏差的影响.不考虑测速公式简化误差,复协方差频移估计测速偏差可以简化为多普勒频移测量偏差.经推导,不考虑发射信号波束开角的窄带测频无偏、宽带测频有偏;考虑波束开角的窄带测频和宽带测频均有偏.相关时延不准确且频谱不对称是该偏差的重要来源.仿真分析...     

频移分离型三维激光多普勒测速仪研究

研究一种采用频移分离方法的新型三维激光多普勒测速仪（３ＤＬＤＶ）。该仪器以单色Ｈｅ－Ｎｅ激光器和单只光电探测器并配合简单的光学发射和接收系统即实现了三维速度分量的同时测量。三个分量的速度信号由声光调制器引入的三种光学频移区分，通过电子滤波器完成信号的相互分离。在光学发射系统设计中采用独特的单轴四光束结构，通过光束组合形成三双光束差动模式的激光多普勒测速仪光。本文中还给出了该仪器的系统设计参数并分析     

1.6μm相干激光测风雷达的速度标定研究

介绍了相干激光测风雷达系统中用转盘进行速度标定的方法,在实验室搭建了激光雷达速度标定装置。采用1.645μm种子注入单频脉冲激光器,在激光中心频率相对种子光移频量约62MHz、转盘直径300mm、转盘速度-47.12～47.12m/s可调、激光出射方向和转盘线速度方向夹角为36°时,采用相干探测的方法测出了多普勒频移并反演出了测量速度;数据处理过程中分别采用最大值频谱估计法和频谱对齐法计算多普勒频移和转盘速度。实验结果显示,频谱对齐法相对于最大值频谱估计法能够提高36.3%的测速精度,因此在激光雷达测风系统中采用频谱对齐法相对于常用的最大值频谱估计法测量的风速精度更高,这对提高相干激光雷达测风的风速精度提供了实验依据和参考标准,验证了频谱对齐法在激光雷达测风的数据处理中的可行性。     

公路超速检测激光测速仪研究（英文）

为了减少公路违章超速现象的发生,使交通安全监测体制更完善,设计并研制了一种可远距离工作的便携式激光多普勒测速系统.阐述了激光多普勒测速的基本原理和光束变换的实现方法,并利用双透镜类望远系统的结构搭建了用于公路超速检测的激光测速仪.理论分析与路边测试试验表明:该激光多普勒测速系统具有长工作距离和大景深的特点,并且可以较高精度获得车辆的行进速度.相比于传统激光测速仪,便携式激光多普勒测速系统提升了中心工作距离并增大了景深.新激光测速仪的中心工作距离为10m,景深为±1m,测速精度可以达到0.1%.     

谐振腔马赫-曾德尔干涉集成光波导陀螺

研究了光学环形腔中的单方向传输光在光学谐振腔中传输的情况，在系统旋转角速率变化时光束会产生频移，在此基础上，设计出一种具有谐振腔马赫-曾德尔干涉集成光波导陀螺结构，可以方便地检测出系统旋转角速率与方向，其检测精度与光波导谐振腔的品质无关。和萨尼亚克集成光波导陀螺相比较，性能价格比有进一步提高的潜力。     

载体振动对差动激光多普勒测速仪的影响

 为了减小载体振动对传统差动激光多普勒测速仪(LDV)测速精度的影响,提出了Janus配置的差动LDV,并对其速度测量的相对误差进行了理论分析与数值仿真。结果表明：Janus配置技术可以近似反演出载体上下振动时的俯仰角,并对速度进行补偿;载体上下振动对传统差动LDV的测量精度有较大影响,而对Janus配置的差动LDV的影响较小;在Janus配置的差动LDV中,当存在俯仰角且大小一定时,随着载体上下起伏速度与运行速度比值增大,速度测量的相对误差增大;当载体上下起伏速度与运行速度的比值为0.01,俯仰角小于10°时,Janus配置的差动LDV的速度测量的相对误差小于0.2%。     

双光束激光多普勒测速系统

激光多普勒测速以其高精度、使用方便而在速度测试领域得到广泛的应用. 本文介绍了激光多普勒测速和双光束测速系统的基本原理,并对流体速度进行了测量,得出了相应的实验结果.     

宽带多普勒测速技术中的发射信号

声波信号作为系统测速的载体,直接影响测速性能,是多普勒测速技术的关键。研究了不同发射信号的频谱特性及基于复协方差法的多普勒频移测量误差。一般假设二相编码信号频谱关于载频对称,但实际上其频谱为不关于载频对称的双边谱,不对称程度由不对称系数量化。不对称系数越小,测频偏差、标准差均越小,即测频性能更佳。仿真实验表明,在不考虑波束开角的点回波模型下,差分重复伪随机Blackman码元幅度调制编码信号与常用的非差分重复伪随机二相编码信号相比:不对称系数低3个数量级;信号频带同带宽内信噪比在0～-10 d B范围内测频标准差约下降2%～20%;信噪比高于10 dB时相对测频偏差约小5‰～6‰。     

激光多普勒测量中信号的误差分析

激光多普勒测量技术在流体以及固体表面测量中得到了广泛的运用。由于影响测量的误差源较多 ,因而在实际的测量过程中 ,激光多普勒测量的精度并不是非常的高。影响测量精度的误差主要是激光多普勒频率增宽 ,高斯光束的干涉以及安装误差。通过控制不同的系统参数 ,可以消除或减小相应的误差     

A geometric analysis of the probe volume in a dual beam laser Doppler velocimeter

The probe volume of the dual beam laser Doppler velocimeter is analyzed from a geometrical standpoint. The volume is graphically reconstructed and the existence of the characteristic dual beam laser Doppler velocimeter fringes is demonstrated. The fringes are analyzed and are shown to be composed of moving tubes or pockets of coherent radiation. The composition of the light is analyzed and the extent of the coherence of the laser radiation within the light pockets is considered. The scattered light from the tubes is analyzed and the coherence enhancement of the fringe structure is shown. This information is used in an attempt to resolve the controversy as to whether the dual beam laser Doppler velocimeter is governed by a fringe counting phenomena or by a beating phenomena of light from two sources of coherent radiation of different frequencies.     

The frequency shifting of laser light by electro-optic techniques

In velocity measurements by the laser Doppler method, a requirement exists for changing the frequency of one light beam with respect to another derived from the same source. This is particularly useful for the determination of the sign of a velocity. The required frequency shifting or single side-band generation can be accomplished by the use of electro-optical effects and a number of possible arrangements are discussed. Trials were made using Kerr cells and electro-optic crystals and single side-band generation demonstrated by a simple Doppler beating experiment. If a low efficiency can be tolerated as in Doppler beating with a reference beam, the production of a pure frequency shifted beam is not difficult up to frequencies of a few megahertz. The differential Doppler or fringe system however requires shifted and non-shifted beams of equal intensity and hence high efficiency conversion is imperative. Radio-frequency driving power requirements may also be a limitation. The theoretical efficiencies of various multi-cell electro-optic arrangements have been calculated as a function of R.F. excitation. The possible efficiency approaches unity as the number of cells is increased.     

Doppler shift of a laser pulse beam scattered by a rotating cone and cylinder

Based on laser radar equations, a Doppler shift model of a laser pulse beam scattered by a rotating arbitrary convex target is reported in this paper. The boundary relations between an incident pulse beam and the detected area elements are analyzed by geometric methods. The Doppler shift characteristics of the rotating cone and cylinder are discussed and the difference between the laser pulse beam and the plane wave scattered from the same rotating target is compared accordingly. Numerical simulations show that the Doppler shift is tightly relevant to their dimensions, speeds, and so on. In the same incidence conditions, the pulse beam and plane wave have difference peak values and the same Doppler shift bandwidth. If the waist radius of the pulse beam is larger, the peak value is higher, and the Doppler shifts are proportional to the speed of the rotating target. By virtue of our theoretical model, we probe into the scattered characteristics of the Doppler shifts of a laser pulse beam, which would benefit target identification in national defense.     

Measurement of absolute flow velocity vector using dual-angle, delay-encoded Doppler optical coherence tomography

Single-beam laser Doppler measurements of flow velocity are only sensitive to the velocity component parallel to the optical axis. We describe a simple modification to a standard Doppler optical coherence tomography (OCT) system using a single sample beam that provides velocity information from multiple angles within the beam. By introducing a glass plate midway into the OCT beam path, the sample beam is divided into several components, each with a different group delay and each providing a separate interferogram with its own effective Doppler angle. By combining the Doppler shift measured in each of these component interferograms, the flow velocity vector is fully determined.     

旋转镜鼓式热像仪的光雷达回波特性

 旋转镜鼓式热像仪对光场的扫描主要由镜鼓来完成，在激光束的照射下，镜鼓棱及其邻域的后向散射不可避免地给散射光引进了一个附加的多普勒频移。对平行光束经热像仪后的动态回波特性进行分析研究，提出了一种测量光束多普勒频移的方法，并建立了相应的实验系统。实验结果与理论分析是一致的，为判别热像仪的工作方式提供了一种可能的方法。     

激光多普勒测速仪中散射光特性的研究

后向散射光特性与多普勒信号的质量密切相关。为了设计高性能的激光多普勒测速仪,运用散斑理论详细分析了激光多普勒信号的强度与散射光斑大小的关系,结合泛函理论给出了计算多普勒电流的散斑表达式,并通过实验的方法研究了回波信号的偏振特性及其强度分布。理论分析与实验结果表明,激光多普勒信号的强度与接收器件光敏面的直径成正比,与光斑的直径成反比;选用光斑较小的圆偏振激光束,并用光敏面尺寸较小的探测器在镜面反射方向上接收信号光,可以大大提高多普勒信号的信噪比,增强系统的探测能力,为提高系统的测量精度创造有利的条件。     

基于Polytec激光测振仪的光存储设备振动测试分析系统

针对光存储设备振动频率高的特点,采用Polytec激光测振仪拾取振动信号,并给出了基于Polytec激光测振仪的光存储设备振动测试分析系统。可用于硬盘盘片、磁头滑块、折臂组件、光盘盘片等振动测试,为光存储设备动态特性的测试和分析建立了良好的实验基础。     

Velocity selective optical pumping and repumping effects with counter and copropagating laser radiations for D<Subscript>2</Subscript> lines of rubidium

The effects of a strong control or pump laser, counter propagating or copropagating with the probe beam, on the probe absorption spectra of ⁸⁵Rb and ⁸⁷Rb-D₂ transitions have been investigated inside a room temperature Rb vapour cell. In both cases a set of strong velocity selective resonance dips are observed at different velocities. Their movements across the Doppler broadened probe absorption profile have been studied for different lock frequencies of the control laser. These spectra are modified by optical pumping effects due to the presence of another hyperfine component of the ground state. A repumping laser, from the dark hyperfine component of the ground level transfers almost 75% of the atoms from the dark state to the pump probe cycle hence reducing the optical pumping effect. A numerical simulation is done to explain the observed spectra. The effect of a control laser on the Lamb dip spectrum of the probe laser has also been investigated. The control beam is used to improve the strength of a weak hyperfine dip on the Doppler broadened probe spectrum. The strength of the hyperfine dip increases by a factor of 3.2 in presence of the control laser. The observed dips show that pump-probe spectroscopy can be used as velocity selectors of atoms.