Design And Implementation Of Refractive Index Measurement System Of Liquid Based On Optical Fiber Sensing

Concentration is an important characteristic parameter used in the daily life and industrial production to characterize the liquid properties of the medium.The concentration of liquid or refractive index is needed to accurately measure in many areas,such as basic research,chemical industry,medical diagnosis,food manufacturing,environmental protection and so on.At present,there are a lot of ways to measure the concentration,the application of more physical experimental methods are mainly gravity method,optical method has diffraction grating method,Young's interference method,slightly incident method.Since the properties of the liquid substance to be measured are not easily changed by the optical method,the refractive index of the liquid is measured optically,and the liquid concentration is measured by the relationship between the refractive index and the concentration.It is the trend of measuring the concentration of the liquid at this stage.Compared to the more widely used.In particular,a large number of new methods have been developed in recent years to detect refractive index of solutions,such as optical waveguide multimode interference,plasma resonance,confocal spherical F-P interferometry,and SPR fiber-based sensing.This design introduces the concept of "differential pressure ratio" by deducing the relationship between solution concentration and refractive index.The optical fiber refractive index measurement system is used to measure the liquid concentration by optical modulation method.This paper covers the process design,process design,selection of key components,system design and implementation of liquid concentration measurement systems.Firstly,this paper introduced the background and significance of measuring the concentration of liquid,commonly used physical experiment methods in liquid concentration,the current research on sensors and liquid concentration detection methods,and the experimental source and content of this subject.In summary,the method of measuring theliquid concentration based on polarization maintaining fiber with linearly polarized light is determined.Secondly,according to electronic theory,Maxwell's equation and Lambert's law,from the relationship between light and substance,the theoretical model of the linear relationship between the solution and the refractive index in a certain concentration range is established.And the reflectivity components of the reflectance of s light and p light are compared and analyzed.Based on the system of liquid refractive index measurement in optical fiber sensor,the concept of "differential pressure ratio" is introduced,and the relationship between the refractive index and the pressure difference ratio is deduced theoretically.Then,the overall design scheme of liquid concentration measurement system based on optical fiber sensor is proposed,and the selection of key components and the design of process are introduced in detail.In the actual measurement of the optical system,there are some factors that affect the measurement accuracy,such as the unstable factors of the light source,the circuit noise in the photoelectric conversion process,etc.,will affect the liquid refractive index measurement results.In order to eliminate the adverse effects of these factors,critical techniques have been added to the system to optimize the measurement.Thirdly,it introduces the development of information processing part of liquid concentration measurement system,and explains the three aspects of data collection,data processing and data transmission,and describes the data that needs to be transmitted and carries out the technical selection and Program discussion.Finally,the simulation and experiment of the system are carried out.The feasibility and accuracy of the system are proved by comparing the experimental results and the theoretical results.The application and prospect of the liquid concentration measurement system in industrial production are summarized and forecasted.