基于衍射光栅的光纤光栅传感器解调系统研究

研究并实现了一种基于双衍射光栅的光纤布拉格光栅（FBG）传感器解调系统。该解调系统的光路由准直镜、衍射光栅、柱面反射镜和光电探测器等器件组成。通过准直镜后不同波长的平行光束经过衍射光栅后在空间展开,通过柱面反射镜聚焦在光电探测器成像面上。该光路通过采用两块衍射光栅的方法在减小解调系统尺寸的同时提高光学空间分辨力,采用线阵探测器替代扫描机构从而简化系统结构。从理论上分析了光束经过该系统后的空间光强分布,根据光强的高斯分布采用多项式拟合的方法实现了反射光谱峰值定位算法。通过与高精度光谱仪的测量结果对比表明,该解调方法具有较高的波长解调精度和稳定性。

Research of the Demodulation System Based on Diffraction Grating for the FBG Sensors

A demodulation system based on double diffraction gratings for fiber Bragg grating sensors is researched and realized.The optical path for the demodulation system comprises collimator,diffraction gratings,reflector and detector.The parallel beams of different wavelength from the collimator are split spatially when they penetrate the diffraction gratings,and then focused on the imaging plane of the detector by the reflector.A double-grating structure is employed to improve the optical resolution when the geometrical dimension is limited,and the linear array detector is introduced to simplify the mechanical structure.The intensity distribution of the beam when it goes through the demodulation system is analyzed theoretically,and peak search algorithm based on polynomial fit is applied on the reflected spectrum profile in accord with the Gauss mode.The demodulation technique is proved to be with high accuracy and high stability by the result comparison with high accuracy spectrometer.