Surface Tension Sensing And Measurement Based Of Optical Fiber Fabry-perot Cavity Structure

Optical fiber sensor has been developing rapidly in recent years. It has a relatively broad application prospects with the advantages of slight weight, small volume, electromagnetic interference resistence, high insulation resistance and corrosion resistance. Based on the use of optic fiber F-P cavity interferometric sensors, this topic proposed an innovative design of surface tension measurement based on hollow fiber F-P cavity interferometric sensor. This thesis analysed the principle of the method of measuring the surface tension from the theoretical and experimental and stated it’s potential. The main work of the thesis is as follows:1、Referred to academic papers and literature of optical fiber F-P cavity interferometric sensor at home and abroad, this thesis introduced the development background, transmission principle, demodulation method and application prospect of optical fiber F-P cavity interferometric sensor. It also introduced the classification, production and its application of the optical fiber F-P cavity interferometric sensor, especially carried on the detailed classification according to the producing methods; and its advantages and disadvantages of each type is commented.2、Referred to relevant literature of surface tension coefficient measurement, this thesis introduced the background and the importance of surface tension coefficient; Systematic introduced the the traditional measuring methods and optical measuring methods of surface tension coefficient, and analysed the advantages and disadvantages of each method.3、This thsis introduced the production process of hollow optical fiber F-P cavity structure which is used in the experiment. The effect of the different lengths of the hollow optical fiber F-P cavity was experimently analysed, and this was for the choice of the optimal length.4、A measurement based optical interference method of liquid surface tension coefficient is proposed. An FP cavity formed by a single mode fiber fusion spliced with a hollow fiber, which was contact to the liquid surface. In experiment, five different liquids in the same temperature and distilled water in different temperatures were measured. Using the method of least squares linear fitting to deal with the results. The method is simple in structure, easy to operate and high sensitivity, which can provide reference in practice.