| The continuous development of the Internet of Things technology has brought human beings an efficient and convenient life,and at the same time,the demand for information-aware components has gradually increased due to social progress.As a tool for information perception and transmission,sensors are highly concerned by scientific researchers today.Magnetic field sensors have more important research significance because they are widely used in social production and daily life.In recent decades,many magnetic field sensors have been designed based on the magneto-optical characteristics of magnetic fluids,but there are still some shortcomings such as slow response speed and high cost.This paper uses the magneto-optic dichroism effect of the magnetic fluid to design a new magnetic field sensing system based on the detection of the polarization state of the light.The main research contents are as follows:?1?Briefly describe the research value of magnetic field sensors and their application in emerging technologies,introduce several different principles of magnetic field sensors and analyze their advantages and disadvantages;briefly describe the research background,composition and classification,optical properties of magnetic fluids,and summarize the research status of nature design magnetic field sensors.?2?The D-shaped optical fiber is made by the side arc groove polishing method,the side parabolic surface is immersed in the magnetic fluid,and an external magnetic field parallel to the side parabolic surface is applied in the direction perpendicular to the optical fiber to design a fiber with fast response speed and good robustness Magnetic field sensor.Based on optical polarization modulation,the effects of magnetic fluid concentration and magnetic field strength on the sensitivity of optical fiber magnetic field sensors are studied.The study found that increasing the magnetic fluid concentration can improve the sensitivity of the magnetic field sensor;the increase in the external magnetic field increases the depth of light polarization modulation.When the volume ratio of magnetic fluid to water is 1:6,and the magnetic field changes from 100 Oe to 200 Oe,the light polarization degree changes to 0.282×10-3/Oe.The signal processing system of the magnetic field sensor is composed of a polarization beam splitter and a photodetector.Compared with other types of magnetic field sensors,the structure is simple and the cost is low.?3?Design of magnetic field sensor based on magnetic fluid spatial light polarization modulation.Because the manufacturing steps of D-shaped optical fiber are complicated and difficult to manufacture,based on the original research,this paper simplifies the structure of the magnetic field sensor and designs a magnetic field sensor with a simpler structure and higher sensing sensitivity.The cuvette containing the magnetic fluid is placed between two magnets,and the light enters the cuvette perpendicularly and is perpendicular to the external magnetic field.The external magnetic field induces the magnetic fluid to generate a magneto-optic dichroism effect,which makes the vibration parallel and perpendicular to the magnetic field.According to the output voltage of the photodetector,the polarization state of light can be calculated to measure the external magnetic field.Based on the detection of light polarization state,the relationship between the concentration of magnetic fluid,the strength of the magnetic field and the sensitivity of the magnetic field sensing system is studied.The study found that a high concentration of magnetic fluid can improve the sensitivity of the magnetic field sensor;when the magnetic fluid concentration is 1%and the magnetic field changes from 25 Oe to 50 Oe,the light polarization degree changes to 0.384×10-3/Oe.The magnetic field sensor structure improves the sensor sensitivity on the original basis.In addition,a repeated magnetic field measurement experiment was performed on the magnetic fluid with a concentration of 3%to test the effect of hysteresis on the magnetic field sensor. |
PDF Full Text Request