Study On The Refractive Index Measurement Technology Of A Little Flowing Liquid

The refractive index is one of the important optical parameters of the materials.The refractive index of a material is closely related to other important physical,biological and chemical properties.By measuring the refractive index,other widely used characteristic parameters such as concentration,biomedical marker,salinity and fermentation kinetics can be indirectly obtained.This indirect detection method promises reliable & real-time results and minimal sample preparation with no fluorescent labeling required.More than that,the refractive index can be used as an indicator to monitor the dynamic changing process of liquids.It is necessary and important to determine the refractive index of some liquids in the chemical,pharmaceutical,petroleum and many other industrial departments and science research.In recent years,with the development of refractive index measurement technology,the demand for continuous measurement and measuring the refractive index of small volume liquid is gradually expanding.In this thesis,we introduced a variety of refractive index measurement methods,and studied the principle of the optical critical-angle method in depth.In order to verify the performance of the technology,we designed a flow refractive index measurement system.Based on the traditional critical-angle refractometer,we designed a flow channel structure for the measuring pool which is containing the liquid.The liquid is fluidity through a pair of water inlet/outlet,so that the refractive index of the flowing liquid can be measured continuously.The width of the measurement channel is designed to be tiny,which can realize the measurement of small volume liquid.Through a series of refractive index measurement experiments,it is proved that the system has good accuracy,stability and practicability.In order to solve the problem of high-efficiency measurement and smaller volume liquid measurement,the technology was further optimized and improved from two directions.First,in order to improve measurement efficiency,we increased the number of flow channels.the design of a measurement pool with two independent liquid flow channels,can achieve to measure the refraction index of different liquids at the same time,and the system has self-check function;Second,in order to measure the refractive index of micro liquid,we reduced the channel width.We designed a microchannel measurement pool based on microfluidic technology,and the technology was applied in the refractive index matching of a microfluidic chip.We did a series of experiments to verify the above techniques,and the experimental results showed that both of the two improved techniques could solve the limitations in the actual measurement scenarios and obtain accurate measurement results.