【摘要】：隨著中國高新技術(shù)的發(fā)展，在航空航天、能源和材料工業(yè)等集中的領(lǐng)域，無損評價的要求最為急切。由于傳統(tǒng)的超聲探頭檢測時需要在探頭與樣品之間用耦合劑完成能量的傳遞，而耦合劑會對樣品表面產(chǎn)生污染，且在一些有毒、高溫、高壓、高輻射等狀態(tài)下無法進(jìn)行檢測。 本文主要完成了對激光外差干涉系統(tǒng)的設(shè)計以及對信號的處理與分析，首先介紹了激光外差干涉系統(tǒng)的設(shè)計框圖，闡述了該系統(tǒng)的工作原理以及實際光路的搭建模型，并分析了系統(tǒng)中所使用的幾個主要光學(xué)元器件的自身特性及作用。介紹了對于外差干涉信號進(jìn)行處理的方法。其次通過選擇用FPGA對該系統(tǒng)采集的信號進(jìn)行處理，分析了完成信號處理所用的算法，以及選擇何種編程語言的原因，設(shè)計了完成信號處理需要的各個模塊，，并對每個模塊的功能進(jìn)行了仿真驗證。最后對整個系統(tǒng)進(jìn)行了一個仿真，將采集到的信號處理以后從仿真圖中顯示了出來，從而獲得了激勵所產(chǎn)生的激光超聲振動位移與其頻率的關(guān)系。 對數(shù)據(jù)的分析是通過對靜態(tài)的數(shù)據(jù)變化、動態(tài)數(shù)據(jù)變化以及超聲探頭獲得的數(shù)據(jù)為對比，證明系統(tǒng)設(shè)計的有效性，以及設(shè)計的激光外差干涉系統(tǒng)可以檢測到激光超聲信號，同時獲得了頻率為2.35MHz的激光超聲信號，激勵光斑與反射光斑越近，檢測效果越準(zhǔn)確，然后再通過設(shè)計的FPGA系統(tǒng)實現(xiàn)對數(shù)據(jù)的仿真，與動態(tài)以及超聲探頭獲得的數(shù)據(jù)對比發(fā)現(xiàn)檢測到頻率為2.35MHz的激光超聲信號時，振動位移較大，反之較小。
[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.
【學(xué)位授予單位】：中北大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TN791;TN911.7

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