- 學位論文
光纖光柵環形雷射於振動感測系統之應用
Application of fiber Bragg grating ring laser to vibration sensing system
摘要
本研究提出一種基於環形雷射的光纖布拉格光柵(Fiber Bragg Grating, FBG)振動感測系統架構，環形雷射部分以980nm泵浦光源、摻鉺光纖(Erbium Doped Fiber)、分波多工(Wavelength Division Multiplexing)、循環器(Circulator)和兩個波長相同的光纖布拉格光柵組成，當感測端之光纖布拉格光柵受到外在的物理參數影響，例如溫度、應變和振動等等，會使光纖布拉格光柵的中心波長產生偏移，造成環形雷射功率降低，此時即可使用強度調變技術來量測所受的外在物理參數。 此篇論文我們分別測量兩種振動，分別為受力式振動和自由式振動，受力式振動為外加振動在光纖布拉格光柵上，量測作用在光纖布拉格光柵上的振動，而自由式振動我們以懸臂樑來做實驗，透過施加應變使其自由性振動，量測懸臂樑的自然頻率，結果證明懸臂樑自然頻率與理論值相似。
並列摘要
In this study, we propose a fiber Bragg grating vibration sensing system based on ring laser. The ring laser section is composed of 980nm pump laser, erbium doped fiber, wavelength division multiplexing, optical circulator and two same wavelengths of fiber Bragg grating. When the sensing fiber Bragg grating is affected by external physical parameters, the center wavelength of the fiber Bragg grating will be shifted. The external physical parameter such as temperature, strain and vibration. It will cause the ring laser power decrease. We can utilize the intensity modulation technique to measure the vibration. This paper we measure two kinds of vibration. We apply vibration signals on fiber Bragg grating to detect the frequency of vibration. Another experiment is measure the vibration signal of cantilever structure. The results show the natural frequency of cantilever structure is similar to the theoretical value.