【作者】 杜军；

【导师】 曲彦臣；

【作者基本信息】 哈尔滨工业大学 ， 物理电子学， 2014， 博士

【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。更多还原

【Abstract】 Doppler Lidar is a powerful tool for velocity measurements of a moving target and wind. According to its working principle, it can be mainly divided into direct detection Doppler Lidar and coherent detection Doppler Lidar. Each of them has obvious advantages and insurmountable disadvantages as well. Coherent Doppler Lidar is difficulty to be applied in engineering practice widely, because its detective method requires a rigorous laser line width, a frequency stability, and optical alignment. Direct detection Lidar, for its edge filter transmittance characteristics restriction, is hard to reach high measuring accuracy and wide measuring range. According to this situation, this paper investigates two aspects of contents as followed:Firstly, this paper proposed a fitting type working manner for direct detection Mie Doppler wind Lidar that utilizes the Fabry-Perot interferometer double-edge technique, and theoretical research will be done at the same time. Based on the measuring error characteristics of the Doppler wind Lidar, the fitting type working manner, by changing the working point of outgoing laser on Fabry-Perot transmission curve for the requirement of real wind measurement, always uses the maximum accuracy curve party to measure the wind for increasing the measuring accuracy and range.Theoretically, it has been proved that normal Fabry-Perot double-edge Mie direct detection Doppler wind Lidar employing the fitting working manner, can improve the measuring accuracy as high as possible with no need to consider wind measuring range restrict when designing the system parameters, and can adjust its own state to suite the wind requirement for the best measuring result.It has been proved theoretically that the special angle tuned Fabry-Perot double-edge Mie direct detection Doppler wind Lidar designed with fitting working manner, comparing with the normal Fabry-Perot double-edge Mie direct detection Doppler wind Lidar, has the same minimum measuring error, but its measuring error range is5.76times less than the latter.Secondly, this paper proposed a new kind of Doppler shift detection method. It uses the phase modulator to make the signal light generate the first order sidebands from the original frequency component (carrier wave), then utilizes the Fabry-Perot interferometer to tune the amplitude and phase of them for generating the beat frequency signal with fixed frequency. This beat frequency signal is used to measure Doppler frequency shift. The beat frequency signal is generated from the different signal light frequency components, which undergo the same space-time and will not reduce coherence due to increase of detection range. No needing a tall order for optical structure and light source, extramly high beat frequency efficiency can be obtained spontaneously. This fundamentally solves the problems of coherent detection method.Theoretically and experimentally, it can be proved that the beat frequency signal amplitude and phase of phase modulation signal light can be used to measure the Doppler shift; measuring range of the Doppler shift measuring method using the beat frequency signal phase is twice as that of the Fabry-Perot single edge technique, and no needs to detect the energy of signal light.Experimentally, utilizing the virtual digital phase-locked amplifier based on LabView visual programming languages and Data Acquisition Card to extract the phase and amplitude of beat frequency signal of phase modulation has been realized; it has been proved that the Doppler shift measuring method of the beat frequency signal amplitude has a higher ability to resist external electromagnetic interference than the normal edge technique Doppler shift measuring method, the measuring accuracy of it is10times higher than that of normal edge technique under the condition of high external electromagnetic interference.In theory, Measurement error formula of phase modulation beat frequency signal Doppler shift measuring methods have been derived out; the simulation results of them fit the experimental results very well; by using these formula, the best phase modulation frequency and depth for this kind Doppler shift measuring method are gotten.更多还原