基于FPGA的光外差干涉信号处理方法研究
发布时间：2018-11-06 09:46
【摘要】：随着中国高新技术的发展，在航空航天、能源和材料工业等集中的领域，无损评价的要求最为急切。由于传统的超声探头检测时需要在探头与样品之间用耦合剂完成能量的传递，而耦合剂会对样品表面产生污染，且在一些有毒、高温、高压、高辐射等状态下无法进行检测。 本文主要完成了对激光外差干涉系统的设计以及对信号的处理与分析，首先介绍了激光外差干涉系统的设计框图，阐述了该系统的工作原理以及实际光路的搭建模型，并分析了系统中所使用的几个主要光学元器件的自身特性及作用。介绍了对于外差干涉信号进行处理的方法。其次通过选择用FPGA对该系统采集的信号进行处理，分析了完成信号处理所用的算法，以及选择何种编程语言的原因，设计了完成信号处理需要的各个模块，，并对每个模块的功能进行了仿真验证。最后对整个系统进行了一个仿真，将采集到的信号处理以后从仿真图中显示了出来，从而获得了激励所产生的激光超声振动位移与其频率的关系。 对数据的分析是通过对静态的数据变化、动态数据变化以及超声探头获得的数据为对比，证明系统设计的有效性，以及设计的激光外差干涉系统可以检测到激光超声信号，同时获得了频率为2.35MHz的激光超声信号，激励光斑与反射光斑越近，检测效果越准确，然后再通过设计的FPGA系统实现对数据的仿真，与动态以及超声探头获得的数据对比发现检测到频率为2.35MHz的激光超声信号时，振动位移较大，反之较小。
[Abstract]:With the development of high and new technology in China, the requirement of nondestructive evaluation is most urgent in the fields of aerospace, energy and material industry. Because the traditional ultrasonic probe needs to transfer the energy between the probe and the sample by coupling agent, the coupling agent will pollute the surface of the sample, and can not be detected under some toxic, high temperature, high pressure and high radiation conditions. In this paper, the design of laser heterodyne interference system and the signal processing and analysis are mainly completed. Firstly, the design block diagram of laser heterodyne interference system is introduced, and the working principle of the system and the building model of practical optical path are described. The characteristics and functions of several main optical components used in the system are analyzed. The method of processing heterodyne interference signal is introduced. Secondly, by using FPGA to process the signal collected by the system, the algorithm used to complete the signal processing is analyzed, and the reasons of which programming language is chosen, and the modules needed to complete the signal processing are designed. The function of each module is verified by simulation. Finally, the whole system is simulated, the collected signal is displayed from the simulation diagram, and the relationship between the laser ultrasonic vibration displacement and its frequency is obtained. The analysis of the data shows the validity of the system design and the laser heterodyne interference system can detect the laser ultrasonic signal by comparing the static data change, the dynamic data change and the data obtained by the ultrasonic probe. At the same time, the laser ultrasonic signal with frequency of 2.35MHz is obtained. The closer the excitation spot is to the reflected spot, the more accurate the detection effect is. Then the simulation of the data is realized through the designed FPGA system. Comparing with the data obtained by the dynamic and ultrasonic probe, it is found that the vibration displacement is larger when the frequency of the laser ultrasonic signal is 2.35MHz, and the contrary is smaller.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN791;TN911.7
本文编号：2313929
[Abstract]:With the development of high and new technology in China, the requirement of nondestructive evaluation is most urgent in the fields of aerospace, energy and material industry. Because the traditional ultrasonic probe needs to transfer the energy between the probe and the sample by coupling agent, the coupling agent will pollute the surface of the sample, and can not be detected under some toxic, high temperature, high pressure and high radiation conditions. In this paper, the design of laser heterodyne interference system and the signal processing and analysis are mainly completed. Firstly, the design block diagram of laser heterodyne interference system is introduced, and the working principle of the system and the building model of practical optical path are described. The characteristics and functions of several main optical components used in the system are analyzed. The method of processing heterodyne interference signal is introduced. Secondly, by using FPGA to process the signal collected by the system, the algorithm used to complete the signal processing is analyzed, and the reasons of which programming language is chosen, and the modules needed to complete the signal processing are designed. The function of each module is verified by simulation. Finally, the whole system is simulated, the collected signal is displayed from the simulation diagram, and the relationship between the laser ultrasonic vibration displacement and its frequency is obtained. The analysis of the data shows the validity of the system design and the laser heterodyne interference system can detect the laser ultrasonic signal by comparing the static data change, the dynamic data change and the data obtained by the ultrasonic probe. At the same time, the laser ultrasonic signal with frequency of 2.35MHz is obtained. The closer the excitation spot is to the reflected spot, the more accurate the detection effect is. Then the simulation of the data is realized through the designed FPGA system. Comparing with the data obtained by the dynamic and ultrasonic probe, it is found that the vibration displacement is larger when the frequency of the laser ultrasonic signal is 2.35MHz, and the contrary is smaller.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN791;TN911.7
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