基于光纤干涉法的液体表面张力系数测量及温度影响研究

Liquid surface tension coefficient measurement and temperature impact based on optical interference method

为了提高液体表面张力系数的测量精度,并充分发挥光纤干涉法的高精度、非接触等优点,提出了一种利用干涉原理的空心光纤(HOF)液体表面张力系数测量方法。即利用HOF一端与单模光纤(SMF)相连,另一端与待测液面接触形成Fabry-Perot(F-P)腔实现液体表面张力系数的测量。毛细效应使得被测液体进入HOF内,不同的表面张力导致HOF形成的F-P腔腔长发生变化,通过检测F-P腔两个相邻干涉峰的间距就可以间接得出液体的表面张力系数大小。实验中,分别测定了相同温度下5种不同液体的表面张力系数和不同温度下蒸馏水的表面张力系数,对测量的结果进行最小二乘法线性拟合。实验中,温度的改变采用水浴加热法,不同温度下蒸馏水表面张力系数的测量结果与理论值的最大误差为0.26%。本文方法结构简单,容易操作,有较高的灵敏度,可为实际液体表面张力系数测量提供参考。

In order tO improve the accuracy of surface tension coefficient measurement, and to give full play to the advantages of optical interference method,a novel measurement based on optical interference method for liquid surface tension coefficient is proposed. An FP cavity is formed by a single mode fiber fusion spliced with a hollow fiber,which contacts the liquid surface. As the liquid rising into the hollow fiber by capillary phenomenon, the length of FP cavity is changed with different liquids. The surface tension coefficient measurement then can be achieved by monitoring the adjacent interference wavelength spacings. In experiment, 5 different liquids in the same temperature and distilled water in different temperatures are measured using the method of least squares linear fitting. Distilled water is heated by water bath heating method. The experimental result is similar to the theoretical value, and the error is less than 0.26 %. The presented method is with simple manufacturing, easy operation, and high accuracy, so it is suitable for measurement in practice.