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Research On Fiber-optic Vector Magnetic Field Sensor Based On Magnetic Fluid

Posted on:2021-01-24Degree:MasterType:Thesis
Country:ChinaCandidate:Y X SongFull Text:PDF
GTID:2428330605978051Subject:Optical engineering
Abstract/Summary:PDF Full Text Request
As an important branch of sensing technology,magnetic sensing plays an indispensable role in many fields such as national defense and military,biomedicine,aerospace,machinery industry,and so on.With the expansion of the application field and the complexity of the measurement environment,the optical fiber magnetic field sensor has many inherent advantages compared with the traditional magnetic field sensor,such as:simplified structure,wide measurement range,high detection sensitivity,and strong resistance to electromagnetic interference.Even in harsh environments,such as flammable and explosive,strong corrosion,strong electromagnetic interference,etc.,fiber-optic magnetic field sensors have completely replaced traditional magnetic field sensors.Magnetic fluid with its unique physical properties and excellent optical characteristics widely favored by researchers.In recent years,the research works on magnetic field intensity of magnetic fiber-based optical fiber sensors had made continuous progress.However,the direction of magnetic field as an important parameter is usually ignored.In view of this,the research work in this paper will focus on the measurement of vector magnetic field intensity and direction.Based on this purpose,we designed and verified two novel optical fiber magnetic field sensors.The main research contents are given as follows:Using a high-temperature melting taper method,a single-mode optical fiber and a quartz capillary are melted into one body to obtain a novel optical fiber structure.This structure can excite the high-order mode in the optical fiber to the fusion of the capillary tube wall and the fiber cladding,inject the magnetic flow into the microcapillary in the structure and encapsulate,using the characteristics of the magnetic fluid refractive index in the microcapillary controlled by the magnetic field to Change the effective refractive index difference between the two main transmission modes in the fiber structure,and then realize the interference between the light wave modes.By detecting the change of the interference spectrum,the magnetic field information is effectively converted into the optical information in the optical fiber,and the fabrication of the all-fiber magnetic field sensor is realized.The proposed optical fiber sensor has a magnetic field sensitivity of 113 pm/mT in the range of 0-110mT.Based on the anisotropic distribution characteristics of magnetic nanoparticles in capillary in magnetic fluid,an optical fiber sensor with dual fiber channels was designed and fabricated.The proposed fiber-optic vector magnetic field sensor is numerically simulated by using COMSOL Multiphysics.The simulation results show that the distribution of hybrid mode in the fiber optic sensor is not only related to the magnitude of the magnetic field but also to the direction of the magnetic field.The effects of magnetic field intensity,magnetic field angle,and fiber axis angle parameters on the performance of the magnetic field sensor were studied.The experimental results show that the sensitivity of up to 244 pm/mT to the magnetic field intensity can be achieved.In addition,at any angle,the magnetic field angle sensitivity can be expressed as:dy/dx?0.2? cos[(x-133.13)?/93.57],and the angle error generated during the experiment is only ±1.4°.The proposed optical fiber sensor effectively achieves the purpose of measuring the strength and direction of the vector magnetic field simultaneously.
Keywords/Search Tags:Magnetic field monitoring, Fiber optic sensor, Mode interference, Magnetic fluid, Tunable refractive index
PDF Full Text Request
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