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采用紫外写入光纤 Bragg光栅研究其应变传感特性。光纤光栅可借助外界应力引起轴向应变和折射率变化造成光栅 Bragg反射波长移动。在温度 2 0℃ ,利用波长在 4 0 0～ 1 80 0 nm范围色散的光谱仪并用In Ga As P/ In P ELD作宽带光源 ,从实验上测量了光纤光栅的应变与 Bragg反射波长间的关系 ,结果表明Bragg反射波长移动与光纤光栅外界应力变化在 1 55.4～ 1 56.8nm波长范围呈线性。外界应力引起的光纤光栅灵敏度为 1 .2 1 1 pm/ με,与理论计算结果基本一致。利用光纤光栅的应变传感特性 ,设计并制备了压力传感头。它由上、下两金属板和上金属板上可精密调节的两螺旋组成。光纤光栅的两端被分别固定在上、下金属板的定点上。上金属板可通过精密调节螺旋产生微小升降并作为荷重台面。在光纤伸长应变范围内通过螺旋调节 ,使光纤光栅产生尽可能大的伸长 ,以保持测试有较大线性范围 ;同时在 2 0℃恒温条件下 ,确定压力传感头的测试零点。用此压力传感头 ,在同一板材的不同厚度测量了压力变化引起 Bragg反射波长的移动 ,表明 :选择不同材料或同种材料不同厚度的金属板材可设计不同量程范围。这种压力传感头可适应不同量程的压力或荷载测量。
The strain sensing characteristics of UV-written fiber Bragg grating were studied. The FBG can cause the grating Bragg reflection wavelength to move by the change of axial strain and refractive index caused by external stress. The relationship between strain and Bragg reflection wavelength of fiber grating was experimentally measured at 20 ℃ using a spectrometer with wavelength dispersion in the range of 400 ~ 180 ~ nm and In Ga As P / In P ELD as broadband light source The results show that the wavelength of Bragg reflection wavelength and the external stress of FBG change linearly in the range of 1 55.4-1 56.8 nm. The sensitivity of FBG caused by external stress is 1 2 1 1 pm / με, which is basically consistent with the theoretical calculation. Using the strain sensing characteristic of fiber grating, a pressure sensing head was designed and prepared. It is composed of upper and lower metal plates and two spirals which can be precisely adjusted on the metal plate. The two ends of the fiber grating are respectively fixed on the fixed points of the upper metal plate and the lower metal plate. The upper plate can be finely adjusted spiral screw to produce a small lift and as a load table. In the fiber elongation strain range through spiral adjustment, the fiber grating to produce the greatest possible elongation to maintain a larger test linear range; at the same time at 20 ℃ constant temperature conditions to determine the pressure sensor head test zero. Using this pressure sensing head, the pressure change induced by the Bragg reflection wavelength was measured at different thicknesses of the same plate, indicating that the selection of different materials or metal sheets of the same material with different thicknesses allows the design of different ranges. This pressure sensor head can adapt to different ranges of pressure or load measurement.