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题名	幅频调制的远程检测及甄别
作者	黄灿鸿
文献子类	硕士
导师	范薇
关键词	幅频调制 FM-to-AM 波形检测 Waveform detection 光谱分析 Spectral analysis OMP算法 OMP algorithm
其他题名	Remote measurements and screening of FM-AM on high power laser
英文摘要	随着大型高功率激光装置的发展，与之相关的各种新技术也得到不断地发展。在高功率激光装置中，为了减少压缩靶丸时激光光束的空间不均匀性，并且抑制激光传输过程中的横向受激布里渊散射，都需要通过相位调制来展宽激光的光谱。激光的光谱被展宽之后，由于光学器件的光谱透过率不均匀，激光的振幅会出现调制现象，这种现象被称为幅频调制效应。幅频调制效应严重危害高功率激光装置的安全运行，为了避免幅频调制的影响，在高功率激光装置中需要对幅频调制进行调制深度的检测以及调制频率的甄别。本文设计了一套幅频调制的远程检测及甄别装置，开展了幅频调制监测的相关实验，并取得了符合预期的实验结果。本文的主要内容包括： 1. 以傅里叶变换为工具，采用分析传递函数的方法，建立了幅频调制效应的理论模型，分别讨论了频率传递函数和振幅传递函数对幅频调制的影响，并且分析了幅频调制中振幅调制信号的频谱结构，证明了幅频调制中存在的频率值是相位调制频率的整数倍，接着在理论上介绍了标准具效应、再生放大以及频率转换三种产生幅频调制的原理。 2. 提出一套幅频调制检测系统的设计方案，该设计方案包含两个部分，其中一部分是波形采集模块，该模块的作用是将宽频1053nm激光的波形复制到单频1550nm激光上，从而避免了在后续的检测过程中再次引入额外幅频调制的难题，第二部分是数据处理模块，该模块以VISA库和SCPI命令为基础，实现了示波器与计算机之间的通信，然后采用多项式拟合的方法，从示波器采集的波形中提取出了幅频调制信号，接着采用OMP算法去除信号中的电子噪声，并且得到幅频调制信号的频谱结构，最后计算出一个准确的幅频调制深度作为算法的结果。 3. 在实验上测试了幅频调制检测系统，并且得到了实时的检测结果。实验上通过波形采集模块对两路幅频调制信号进行采集，验证了多路信号检测的功能，并且比较了1053nm激光和1550nm激光在光纤中传播时产生的幅频调制效应，证明了1550nm单频激光在远程检测中的优势。实验上还比较了OMP算法处理前后的波形，证明了OMP算法去噪的能力，同时也比较了OMP算法和多次采样取均值的结果，验证了OMP算法的准确性，最后介绍了幅频调制检测软件的工作界面，通过合理地设计软件界面，帮助操作者更高效地进行实验。; With the development of high-power laser devices, a variety of related new technologies have also been developed continuously. In the high power laser device, in order to reduce the spatial inhomogeneity of the laser beam when the target is compressed, and in order to suppress the Transverse Stimulated Brillouin Scattering during the laser transmission, it is necessary to broaden the spectrum of the laser by phase modulation. After broadening the spectrum of the laser, the amplitude of the laser will appear to be modulated, which due to the inconsistent spectral transmittance and this phenomenon is called FM-to-AM. In order to avoid the influence of the FM-to-AM, the modulation depth and the modulation frequency of the FM-to-AM are required to be detected, which can seriously harm the safe operation of the high power laser device. In this paper, a set of remote detecting and screening FM-to-AM device is designed, and the experiment of this FM-to-AM detecting device is carried out, and the experimental results are in accordance with the expected results. This paper mainly consists of the following three sections: 1. With Fourier transform as the tool, the theoretical model of FM-to-AM effect is established by analyzing the transfer function. The effects of frequency transfer function and amplitude transfer function on FM-to-AM effect are discussed respectively. The spectral structure of amplitude modulation signal in the FM-to-AM effect is also analyzed. It is proved that the frequency in the amplitude modulation is an integral multiple of the phase modulation frequency. 2. Proposed the design of a set of remote detecting and screening FM-to-AM system. The design consists of two parts, one of which is the waveform acquisition module, the role of the module is to copy the waveform of the 1053nm laser to a single frequency 1550nm laser, which avoiding the introduction of additional amplitude modulation in the subsequent detection process. The other part is the data processing module, the module used the VISA library and SCPI command in the communication between oscilloscope and computer, then, the amplitude modulation signal is extracted from the raw data by using the polynomial fitting method. Then, the OMP algorithm is used to remove the electronic noise in the signal, and the spectral structure of the amplitude modulation signal is also obtained. Finally, an accurate modulation depth is calculated as the result of the algorithm. 3. The FM-to-AM detection system is tested experimentally, and the real-time result is obtained. Through the cooperation of two waveform acquisition modules, the function of multi-channel signal detection is verified, and compared the FM-to-AM in the 1053nm laser and 1550nm laser during transmission in the optical fiber, the advantage of 1550nm single frequency laser in remote detection is illustrated. The waveform after OMP algorithm processing is also compared with the raw data, which prove the denoising ability of the OMP algorithm. At the same time, the result of OMP algorithm is also compared with the result of multiple averaging, and the accuracy of the OMP algorithm is verified. Finally, the software interface of FM-to-AM detection system is introduced, by designing the software interface rationally, the operator can be experimented more efficiently.
学科主题	光学工程
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/30926]
专题	中国科学院上海光学精密机械研究所
作者单位	中国科学院上海光学精密机械研究所
推荐引用方式 GB/T 7714	黄灿鸿. 幅频调制的远程检测及甄别[D].

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