相位调制激光多普勒频移测量方法的误差研究

为了能够对相位调制激光多普勒频移测量方法进行定量分析以及优化设计,使其在实际应用中获得最佳测量结果,从该多普勒频移测量方法的工作原理出发,对其测量误差分布规律进行了理论与实验研究,建立了该方法的测量误差模型。并利用该模型对此测量方法的频移测量精度等方面受相位调制频率和相位调制深度的影响进行了理论研究,发现当相位调制频率为Fabry-Perot干涉仪透射率曲线半峰全宽的0.63倍以及相位调制深度为1.08时,该方法的测量精度可以达到最高。     

位相共轭镜耦合到染料激光器中的频移现象

本文建议了一个测量位相共轭镜耦合到染料激光器后,当波长自扫描时,BaTiO_3晶体内的运动光栅的多普勒频移的方法,实验结果表明,多普勒频移Δf<0.2Hz.进一步的分析显示,多普勒频移不能解释朝长波方向扫描的波长自扫描现象.     

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。     

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     

多普勒展宽和多普勒频移在光谱分析中的应用

分析了多普勒展宽和多普勒频移区别，讨论了高斯拟合和弦积分线形分布的差异。利用多道光学分析仪（OSMA）测量HT-6M托卡马克限制器前Hα线形分布，通过高斯拟合由多普勒展宽和多普勒频移分别得出等离子温度和粒子入射速度。     

相位调制激光多普勒频移测量方法的改进

本文对现有相位调制激光多普勒频移测量方法进行了改进,通过定义新的鉴频参量来同时利用相位调制信号直流和交流分量中的有用信息进行多普勒频移测量.由于相位调制信号直流分量中包含着调制信号光的Fabry-Perot干涉仪光强透过率,所以这一改进本质上是将基于Fabry-Perot干涉仪的边缘技术激光多普勒频移测量方法的优势引入到相位调制测量方法中,以提高其自身的性能.理论上证明改进后的相位调制激光多普勒频移测量方法无需对信号光的光强进行测量,所以可以进一步简化探测系统的结构和较少噪声混入的通道.另外,通过对改进前后鉴频和测量灵敏度曲线进行对比,还证明了其具有更高的测量灵敏度和动态范围.实验上对硬目标反射的频移可控信号光进行测量,不但证明了理论的正确性,而且证明了改进后的相位调制激光多普勒频移测量方法,测量动态范围提高约1倍,测量标准偏差降低约35%.     

一种结合两类相位调制激光多普勒频移测量的方法

提出了一种新的激光多普勒频移测量方法,该方法以相位调制拍频信号振幅和相位作为自变量定义新函数,并以该函数作为多普勒频移鉴频参量,将两类相位调制激光多普勒频移测量方法结合.理论上将该方法的鉴频曲线、灵敏度曲线以及误差曲线等与两类相位调制方法的相应曲线进行比较,发现该方法不但继承了相位调制拍频信号振幅方法的工作方式,能够对小频移量进行测量,而且吸收了相位调制拍频信号相位方法的测量能力,具有更高的测量灵敏度和动态范围.通过实验对硬目标反射的频移可控信号光进行测量,证明了理论的正确性,而且通过调整平移参数,可以使该方法的测量动态范围提高约26.8%,更适合对高多普勒频移量进行测量.     

光栅位移激光多普勒遥测技术的研究

研究了利用运动光栅的多普勒效应进行切向位移的遥测技术。提出了测量光路，采用声光调制器作为分光和频移器件并用于鉴向，实现了５０ｍ的远距离光栅位移遥测。达到测量分辨率０．８μｍ，光栅位移４０ｍｍ，最大累积误差优于３４μｍ。并用理论分析和实验，证明了远距离目标的焦深及其计算方法，导出了计算公式。     

用超声衍射效应实现位移测量

本文叙述了用声光调制器实现位移测量的原理。入射光束与声光调制器间的相对运动引起的多普勒频移被反映光衍射的频移中去，通过测量该多普勒频移，测量出声光调制器的位移的大小，文中给出了实验结果。     

基于模拟乘法器的超声多普勒黏度测量实验系统

基于模拟乘法器的超声多普勒黏度测量实验系统以落球法为基础,以频移信号处理电路和数字存储示波器作为数据测量单元的核心,根据多普勒效应原理准确地测算出落球的终极速度,进而得出液体的黏度.该系统可以开展与多普勒效应相关的设计性实验.实验过程中信号的转换、传输及数据测量清晰明了,利于培养学生的综合实验能力和创新能力.     

Simultaneous Measurement of Wind and Aerosol Backscattering in the Troposphere by High Spectral Resolution Lidar with Iodine Filter

We propose a high spectral resolution lidar system which is capable of measuring aerosol backscattering and line-of-sight wind velocity in the troposphere. An iodine vapor filter is used to separate the aerosol and Rayleigh scattering components as well as to discriminate the Doppler shift frequency. The performance of the lidar system is estimated with reasonable parameters. The error of horizontal wind velocity below an altitude of 6 km is less than 0.5 m/s, and accuracy of the aerosol backscattering coefficient is better than 40% below 10 km. This system is particularly suitable for the study of aerosol transportation in the troposphere.     

Research on laser Doppler velocimeter for vehicle self-contained inertial navigation system

An idea of using laser Doppler velocimeter (LDV) to measure the velocity for the vehicle inertial navigation system was put forward. The principle of measuring its own velocity with laser Doppler technique was elaborated and reference-beam LDV was designed. Then Doppler signal was processed by tracking filter, frequency spectrum refinement and frequency spectrum correction algorithm. The result of theory and experiment showed that the reference-beam LDV solved the problem that dual-beam LDV cannot be used for measuring when the system was out of focus. Doppler signal was tracked so that signal-to-noise ratio was improved, and the accuracy of the system was enhanced by the technology of frequency spectrum refinement and correction. The measurement mean error was less than 1.5% in velocity range of 0-30 m/s.     

分子过滤瑞利散射技术测量火焰温度和密度

 为了解决瑞利散射光易受米散射和背景杂散光干扰的问题,发展了结合窄线宽激光器、分子过滤器以及像增强器等技术的分子过滤瑞利散射技术。在图像诊断的基础上,依据测量的碘蒸气吸收光谱曲线,对CH₄/air预混火焰进行了诊断,获得了密度场和温度场分布。距炉面15 mm火焰中心区域处,分子过滤瑞利散射(FRS)技术测量的温度为1 827 K±84 K,密度为0.19 kg/m³,其测温结果与CARS法的测温结果基本吻合。最后分析了FRS技术测温不确定度。实验表明FRS技术具有较高的信噪比,可以定量测量温度和密度信息,有望应用于超音速燃烧流场、紊流场等复杂流场的诊断。     

固体相干成像激光雷达实验

采用单块非平面环形激光器的本地振荡器、种子注入高重复频率Q开关Nd∶YAG激光器的功率振荡器、振镜扫描偏转和光学接收装置、控制和显示等部件构成固体相干成像激光雷达实验装置.利用该装置对目标进行了距离成像和速度测量实验.在图像分辨力为64×64时,获得了成像速度为8 fps的目标距离图像.速度测量平均误差为6%.     

基于边缘技术的大气激光通信原理研究

介绍了利用边缘技术检测激光频率信号，实现大气激光通讯的原理。描述了利用碘分子滤波器作为边缘滤波器的原理性实验系统，并介绍和分析了实验结果。基于边缘技术的通讯系统拥有很窄的光学带宽和很高的激光频率稳定性，系统的光学信号带宽在400MHz以内，并且接收系统仅对激光信号的频率敏感，可以剔除大气中绝大部分的干扰。对于原理实验的不足之处，文中进行了初步的探讨。     

A Doppler lidar with atomic Faraday devices frequency stabilization and discrimination

In this paper, we report a Doppler lidar in which the laser frequency is stabilized and the backscattered light frequency is discriminated by a multi-peak and a less-peak atomic Faraday anomalous dispersion optical filter (FADOF), respectively. The transmission spectrum of the FADOF is stable as it is based on an atomic transition, and slightly tunable with a magnet due to Zeeman effect. The high frequency stability of the FADOF provides a high velocity accuracy; and the tunability of the FADOF transmission spectrum makes the measurement range flexible. We describe an experimental lidar system based on cesium FADOFs, and the experimental error is of±0.74 m/s over velocities ranging from ?40 to +40 m/s.     

多纵模激光F-P标准具双边缘测风可行性分析

讨论采用多纵模激光器作探测光源用于双边缘多普勒激光雷达测风的可行性。给出了多纵模激光器谐振腔腔长与边缘滤波器F-P标准具腔长之间的关系。分析了多纵模双边缘测风的主要特性,计算灵敏度、信噪比和径向测速误差,并与单纵模测风性能进行对比。可用类似单纵模测风中动态频率跟踪技术解决多纵模激光器频率漂移问题。     

测量角度对激光干涉测速的影响分析

对现有激光干涉测速技术中不同的照明角度和测量角度进行了分析,讨论了入射激光和反射激光的角度对测速结果的影响,并结合理论分析进行了实验设计和动态测试,测试结果与理论分析吻合,表明倾斜测试时,其测量结果均低于靶的真实运动速度.对于一维运动的平面靶,可以通过测量结果除以测量角度的余弦值进行修正而得到靶的真实运动速度.透镜口径等因数对测速结果的影响在1%以内.     

测量水的振动频率与水波传播速度

利用激光器、硅光电池等器件,采用光折射方法设计了激光测量水的振动频率与水波传播速度实验.本文介绍了实验原理和装置,测量了水的振动频率和水波向外传播的速度,观察了小块物体落水激起的水波情况.     

Wind measurements with incoherent Doppler lidar based on iodine filters at night and day

An incoherent Doppler wind lidar based on the iodine filter at 532 nm is presented for day and night wind measurements, which was developed by the Key Laboratory of Ocean Remote Sensing of Ministry of Education of China, Ocean University of China. The system operates with a fiber and a narrow-band interference filter to reject daylight. A photon counter is used to improve the detection range. Two iodine filters are used to lock the transmitting laser frequency and to discriminate the Doppler frequency shift, respectively. The method to retrieve the wind profile is described. The detection range of wind profiles (with a 136 m vertical resolution) extends from 100 m to 15 km at night and to 12 km during daytime. The detection range covers the troposphere in the middle and high latitude areas. The comparison experiments between the lidar and radiosonde were performed both during the night and during the day. The standard deviation of the wind direction and speed were 15.5° and 3.1 m/s at night and 15.7° and of 3.2 m/s during the day. This system also has the capability to measure the aerosol backscattering ratio. PACS 42.68.Wt; 92.60.Gn; 92.60.Mt