面向敏感环境的反射式光纤传感防盗系统设计

Design of reflective optical fiber sensing anti-theft system for sensitive environment

为了解决在敏感环境中位置测试容易受到干扰的问题,提出了一种基于反射式光纤传感防盗系统。该系统采用T型光纤探头作为无源传感探头,反射配件安装于安防外壳表面,通过实时测试位置偏移量提供安防预警。探测模块通过预先测试最佳反射位置的方式,将光纤探头与反射配件固定于安防位置上。在获取激光回波信号的基础上,计算了关于位置的场强分布函数。在标定实验中,测试位置由0递增至5.0 mm,响应光功率最大值为18.76μW,方差最大值0.124。当超过3.0 mm后的曲线单调性良好,符合系统设计要求。在不同干扰类型对比实验中,分别对比了湿度、温度、振动对系统测试结果的影响程度。实验结果显示,干扰项的光功率波动无论是线性还是非线性的,其波动范围小于4μW,而真实人为打开条件下,其波动程度大于18μW。与此同时,系统反演计算的位移偏移量也发生显著改变,相比干扰项的位移偏差均值大8倍以上。系统具有传感端无源、灵敏度高、实时性好等优势,可有效应用于敏感环境中的安防监测。

In order to solve the problem that the position test is easily interfered in the sensitive environment,an anti-theft system based on reflective optical fiber sensing is proposed.The system uses a T-type optical fiber probe as a passive sensing probe,and the reflective accessories are installed on the surface of the security enclosure to provide security early warning through real-time testing of position offsets.The detection module fixes the optical fiber probe and the reflection accessories in the security position by pre-testing the optimal reflection position.On the basis of acquiring the laser echo signal,the field intensity distribution function with respect to the position is calculated.In the calibration experiment,the test position was increased from 0 to 5.0 mm,the maximum response optical power was 18.76μW,and the maximum variance was 0.124.When the curve exceeded 3.0 mm,the monotonicity of the curve was good,which meets the system design requirements.In the comparison experiments of different interference types,the influences of humidity,temperature and vibration on the system test results were compared.The experimental results show that whether the optical power fluctuation of the interference term is linear or non-linear,the fluctuation range is less than<4μW,and the fluctuation degree is greater than 18μW under the real artificial opening condition.At the same time,the displacement offset calculated by the system inversion is also changed significantly,which is more than 8 times larger than the average displacement deviation of the interference term.The system has the advantages of passive sensing end,high sensitivity and good real-time performance,and can be effectively applied to security monitoring in sensitive environments.