本論文之研究主題是探討KrF-248nm的準分子雷射於雷射超音波之應用，並且針對半無限體之雷利表面波(Rayleigh Surface Wave)與平板之藍姆波(Lamb Wave)，探討不同特性材料的波傳現象與頻散關係；研究重點為實驗量測與訊號分析。
　　在實驗部份，本研究建立兩套不同波源型態的雷射超音波量測系統，分別為線聚焦量測系統與光柵投射式量測系統；由兩套系統量測半無限域試件之雷利表面波，以波形比對的方式求得表面波波速。對於平板的藍姆波頻散現象，由線聚焦系統所產生的訊號，可利用表面波頻譜分析法，得到頻散曲線；由光柵投射式系統所產生之窄頻訊號，則可運用頻譜分析求得中心頻率，並由交互函數算出訊號之時間差，得到其在頻散曲線上之對應位置。
　　全文針對線聚焦波源的寬頻特性，與光柵投射式波源具有窄頻寬特性，選用不同性質的材料做量測分析，說明兩種波源之頻寬差異，並證明光柵投射量測式系統應用於波傳分析的可行性。

The theme of this essay is the application of KrF-248nm excimer laser on laser ultrasound measurement. Much of the effort is focused on experimental setup and measurement, as well as on signal waveform processing.
For the experimental part, this work develops two measurement systems using two different laser ultrasound sources, namely line-focus measurement system and projection grating measurement system. These two systems can measure Rayleigh surface wave quite accurately with a waveform comparison method. As to the dispersion phenomenon of thin plate’s Lamb wave, the dispersion curves can be obtained by using surface wave spectrum analysis for the line-focus measurement system. While for the narrow bandwidth signals obtained by projection grating system, the dispersion relation is determined by directly spectrum analysis and cross-correlation analysis on the waveforms.
This report emphasizes on the bandwidth characteristics of line-focus source and projection grating source. Using several materials as measurement samples, the difference between these two types of laser ultrasound is demonstrated. It also indicates the possibility of manipulating the bandwidth characteristics of laser ultrasound with the projection grating system.

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