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基于单模-多模-单模光纤(SMS)结构的模间干涉现象,在外界环境变化时SMS光纤结构输出光场散斑图样的变化规律,提出了一种用于振动、应力及温度检测的光纤传感系统。该系统使用光电二极管测量散斑图样部分固定区域的光功率变化,即可得到施加在多模光纤上的外界应力,通过FFT和Hilbert变换,可得到外界振动(频率、幅度)和温度变化信息。对该系统的振动测量和温度测量进行定标后,经实验研究测得,该系统振动测量误差小于0.7Hz,温度测量误差小于5.0%。该系统结构简单,成本低,并可用于多参量的测量。
Based on the phenomenon of inter-mode interference of single-mode-multimode-single-mode optical fiber (SMS) structure, the variation regularity of the speckle pattern of output light field of SMS fiber structure under the change of external environment is proposed. Fiber optic sensing system. The system uses photodiodes to measure the optical power variation in the fixed area of the speckle pattern to obtain the external stress applied to the multimode fiber. The external vibration (frequency, amplitude) and temperature change information can be obtained by FFT and Hilbert transform. After the vibration measurement and temperature measurement of the system are calibrated, the vibration measurement error of the system is less than 0.7Hz and the temperature measurement error is less than 5.0%. The system is simple, low cost and can be used for multi-parameter measurement.