空芯光纤多模干涉型光纤液位传感技术研究

为了测量液位高度变化，采用基于空芯光纤多模干涉效应的方法，研究了在外界介质影响下光源在空芯光纤中多模干涉所产生的干涉谱的变化，进行了基于空芯光纤中多模干涉效应的液位传感实验，研究了该液位传感器的干涉谱与液位变化的关系以及不同折射率液体对测量结果的影响，并分析了实验误差。结果表明，该光纤液位传感器的液位测量范围为0mm~55mm、液体折射率为1.33和1.35时，液位测量灵敏度分别为0.180nm/mm和0.224nm/mm。使用单模-空芯-单模结构的传感器进行液位变化测量是较为精准与可行的。

Research of the liquid level sensing technology based on a hollow fiber multimode interference optical fiber

In order to achieve the purpose of measuring the height change of the liquid,the method based on the multimode interference effect of the hollow core fiber was used to study the change of the interference spectrum caused by the multimode interference of the light source in the hollow core fiber under the influence of the external medium.The liquid level sensing experiment of the multimode interference effect in the core optical fiber was carried out.The relationship between the interference spectrum of the liquid level sensor and the change of the liquid level and the influence of liquids with different refractive indexes on the measurement results were experimentally studied,and the experimental errors were analyzed.The results show that the liquid level measurement range of the fiber optic liquid level sensor is 0mm~55mm,when the liquid refractive index is 1.33 and 1.35,the liquid level measurement sensitivity is 0.180nm/mm and 0.224nm/mm,respectively.It is more accurate and feasible to use a sensor with a single-mode-air-core-single-mode structure to measure liquid level changes.