多普勒激光雷达配合型工作方式与相位调制探测方法的研究

发布时间：2018-03-12 13:33

本文选题：激光多普勒频移　切入点：Fabry-Perot干涉仪　出处：《哈尔滨工业大学》2014年博士论文　论文类型：学位论文

【摘要】：多普勒激光雷达是运动目标速度测量和大气风场遥感的有力工具，根据工作原理其主要可分为直接探测多普勒激光雷达和相干探测多普勒激光雷达。这两类多普勒激光雷达各自存在显著优势的同时，各自也存在着难以克服的缺点。相干探测多普勒激光雷达由于其采用的探测方法对激光器线宽、频率稳定性以及光学对准的要求相当苛刻，使其难于在工程实践中广泛应用；直接探测多普勒激光雷达受其边缘滤波器透过率特性的限制，较难获得到很高的测量精度和测量范围。针对两种多普勒激光雷达各自存在的问题，本文从以下两个方面展开研究：首先，本文提出了直接探测米散射多普勒测风激光雷达的配合型工作方式，并对其进行了理论研究。该直接探测多普勒激光雷达采用的是Fabry-Perot干涉仪双边缘技术，，其配合型工作方式是结合其自身的风速测量误差分布特点，根据实际风速测量的需要，通过动态调整出射激光频率在Fabry-Perot干涉仪透过率谱上的位置，来保证能始终利用Fabry-Perot干涉仪透过率曲线最高测量精度的部分对风速进行测量，从而达到提高测量精度、拓宽测量范围的目的。理论上证明，对于采用配合型工作方式的普通Fabry-Perot双边缘米散射直接探测多普勒测风激光雷达，其鉴频系统的参数设计可以不必考虑风速测量范围的限制来尽量提高测量精度，还可根据实际风速的需要调整自身的状态来获得最佳的测量结果。理论上证明，利用配合型工作方式设计的一种特殊角度调谐Fabry-Perot双边缘米散射直接探测多普勒测风激光雷达，与普通Fabry-Perot双边缘米散射直接探测多普勒测风激光雷达相比，具有相同的最小测量误差，但却具有更小的测量误差范围，两者的误差范围相差5.76倍。其次，本文提出了一种新的多普勒频移探测方法。该方法通过相位调制器使信号光在原有频率成分（载波）的基础上产生正负一阶边带，再通过在Fabry-Perot干涉仪对载波和边带的振幅和相位进行调整，使载波与边带产生固定频率的拍频信号，利用此拍频信号进行信号光多普勒频移测量。由于产生此拍频信号的光波是同一信号光的不同频率成分，它们经历相同的时间和空间，且相干性不会因探测距离的增加而降低，所以无需过高要求系统的光学结构和光源，自然可以获得极高的拍频效率，这就从根本上解决了相干探测方法存在的问题。理论与实验研究同时证明，信号光相位调制拍频信号的振幅与相位参量都可以用来进行多普勒频移测量；与Fabry-Perot干涉仪单边缘技术相比，拍频信号相位参量多普勒频移测量方法的测量范围提高了1倍，且无需对信号光进行能量检测。实验上，实现了利用基于LabView可视化语言与数据采集卡的虚拟数字锁相放大器，对相位调制拍频信号的振幅与相位两个多普勒鉴频参量的提取；证明了相位调制拍频信号振幅参量多普勒频移测量方法比普通边缘技术多普勒频移测量方法具有更高的抗外界电磁干扰能力，当外界具有高电磁干扰时，此拍频信号方法的测量精度可以比边缘技术方法的测量精度高约10倍左右。理论上，推导出相位调制拍频信号多普勒频移测量方法的测量误差公式；其仿真结果与实验结果相吻合；利用该公式获得了此种多普勒频移测量方法的最佳相位调制频率值和相位调制深度值。
[Abstract]:Doppler laser radar moving target velocity is measured and a powerful tool for remote sensing of atmospheric wind field, according to the working principle of the main can be divided into direct detection and coherent Doppler lidar detection Doppler lidar. The two kinds of Doppler lidar exist significant advantages at the same time, each is also difficult to overcome the shortcomings of the Doppler laser coherent detection. Because of its use of radar detection method of laser linewidth, frequency stability and optical alignment requires very harsh, making it difficult to widely used in engineering practice; direct detection Doppler laser radar by the edge filter transmittance limit, is difficult to obtain very high measurement accuracy and measurement range. According to the two kinds of laser Doppler radar problems respectively, this paper study from the following two aspects:
First of all, is presented in this paper with the type of work mode of direct detection of Mie Doppler lidar, and has carried on the theoretical research. The direct detection Doppler laser radar using Fabry-Perot interferometer with double edge technique, the type of work is a combination of its own wind speed measurement error distribution characteristics, according to the actual needs of the wind the measurement, by dynamically adjusting the laser frequency in Fabry-Perot interferometer transmittance spectrum position, to ensure that always interferometer transmittance measurement accuracy curve highest part of the wind speed measured by Fabry-Perot, so as to improve the measurement accuracy, measurement range widening purposes.
Theoretically, the working way of ordinary Fabry-Perot type with double edge Mie scattering direct detection Doppler lidar, the design parameters of frequency discriminator can not consider the wind speed limits of the measurement range to improve the measurement accuracy, but also according to the actual needs of the wind speed to adjust their status to obtain the optimum result.
Theoretically, the direct detection Doppler wind lidar based on a special angle design mode tuned Fabry-Perot double edge scattering meter, compared with ordinary Fabry-Perot double edge Mie direct detection Doppler wind lidar has the same small measurement error, the measurement error range but has a smaller range of error, both a difference of 5.76 times.
Secondly, this paper proposes a new Doppler frequency shift detection method. This method through the phase modulator of the optical signals in the original frequency components (carrier) to generate positive and negative first-order sidebands on the basis of the Fabry-Perot interferometer in the amplitude and phase of carrier and sideband adjusted, so that the carrier and sideband to produce a beat frequency signal with a fixed frequency, the signal light Doppler shift measurement of beat signal. Because of the light from the beat signal is different frequency components of the same signal, they experience the same time and space, and not because of increased coherence detection distance decreases, so without excessive system requirements the optical structure and light source, can achieve high frequency efficiency, which fundamentally solves the problems of coherent detection method.
Theoretical and experimental studies also show that, the optical phase modulation signal amplitude and phase parameters of beat frequency signal can be used to measure the Doppler shift; compared with the Fabry-Perot interferometer single edge technique, the measuring range of the beat signal phase parameter Doppler frequency shift measurement method is improved by 1 times, and there is no need for the signal light energy detection.
In experiment, the use of virtual digital lock-in amplifier LabView visual language and data acquisition card based on the extraction of the phase modulation of the amplitude and phase of the beat frequency signal two Doppler frequency parameters; prove the phase modulation of beat signal amplitude parameters of Doppler frequency shift measurement method is better than ordinary edge technology Doppler shift measurement method has resistance to external electromagnetic interference ability is higher, when the outside world has high electromagnetic interference, the accuracy of the measurement method of the beat signal than the measurement accuracy method of edge technology is about 10 times higher.
Theoretically, the measurement error formula of Doppler shift measurement method for phase modulated beat signal is deduced theoretically. The simulation results coincide with the experimental results. By using this formula, the optimal phase modulation frequency and phase modulation depth value of the Doppler shift measurement method are obtained.

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN958.98

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