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为满足光纤光栅传感系统的解调仪器高分辨力、微型化的需求,针对光纤光栅传感1 550 nm波段设计了光谱成像法光纤光栅解调系统的分光光路系统.成像系统形式采用交叉式Czerny-Turner结构,分析了使用超环面镜代替球面镜、在结构中加入额外的柱面透镜或柱面反射镜以及使衍射光栅工作在发散光条件下的3种校正像散方法的特点,最终选用使衍射光栅工作在发散光条件下的校正像散方法,实现在不加入附加光学元件条件下的像散校正,同时采用小角度入射的方法减小系统彗差.通过Zemax对成像系统进行了参数优化与光线追迹分析,优化结果证明了上述像差校正方法适用于光纤光栅解调.在解调光谱范围内,可明显分开波长间隔为1 nm的光斑,满足光纤光栅解调的分辨力需求.
In order to meet the demand of high resolution and miniaturization of the demodulation instrument of FBG sensing system, a spectroscopic optical system of FBG demodulation system was designed for the FBG sensing 1 550 nm band.The imaging system was of the crossover type Czerny-Turner structure, the characteristics of three methods of correcting astigmatism by using toroidal mirrors instead of spherical mirrors, adding additional cylindrical lenses or cylindrical mirrors to the structure and operating the diffraction grating under divergent light conditions are finally analyzed. Finally, The method of correcting astigmatism which makes the diffraction grating work under the condition of divergent light is adopted to realize the correction of astigmatism without adding additional optical elements and the system of coma aberration is reduced by the method of small angle of incidence.The imaging system is made by Zemax The optimization results show that the above-mentioned aberration correction method is suitable for FBG demodulation. In the demodulation spectrum range, it can obviously separate the light spot with the wavelength interval of 1 nm and meet the resolving power of FBG demodulation demand.