A Research On Measurement Of Liquid Refractive Based Onoptical Fiber Displacement

Refractive index, is one of the important factors to study the optical properties of the liquid. It can reflect much information of liquid, for example, the close relationship between thermo-optical coefficient and it and the close relationship between photoelastic properties and it and so on. Therefore, accurately measuring the refractive index of different liquids has a profound significant in the research fields of liquid properties. With the development of science and technology, the traditional method to measure the refractive index of liquid can not meet the technical requirements. So in order to adapt to the development of lithography lens, infrared system, optical fiber communication and medicine, the study on the new method to measure the refractive index of the liquid becomes an important issue for the study on optical measurement.In order to measure refractive index with high precision, and non-contact intelligent measurement, this thesis carried out the research of measurement of liquid refractive, which is based on the optical fiber displacement.On the basis of the literature home and abroad, the thesis studies the refractive index of the liquid properties, measurement methods and the major factors affecting the measuring accuracy. First of all, base on the laser interferometry, the optical system of measuring the refractive rate of liquid is designed to complete the relevant derived interference theory. Compared with the common optical path, the optical components of the optical system are used less, which can realize the double beam interference. In addition, removing laser speckle theory is applied to remove laser speckle reasonably, which can strengthen anti-interference ability.Secondly, the displacement measurement method in the measurement system is studied and analyzed to puts forward a kind of optic fiber displacement measurement method, which is applied to the radiation type optical fiber displacement sensor. This application can cancel the traditional fringe counting and realize high precision displacement measurement. The measurement resolution can reach micron level.What’s more, demonstration system of the liquid refractive index measurement is set up. And the contrast experiment of the system and the error analysis are also studied. The effect of laser, optical path, optical fiber, color plate and measuring environment on measurement accuracy is also studied.Finally, taking water, sucrose solution as experimental objects, the effect of the temperature and concentration on the refractive index of liquid is analyzed to verify the measurement system. And accuracy of the system and is test and presented and the function of the system is verified.