Study On Self-Oscillated Laser Pumped Cesium Atomic Magnetometer

Magnetic fields are everywhere in nature,from atoms to space.It is one of the important properties of matter and affects our life all the time.To this end,the detection of magnetic fields will enable us to have a deeper understanding of the material and even the nature,and change our lives.As an important tool for magnetic field detection,magnetic measuring instruments have been paid much attention by relevant research teams in various countries.At present,various kinds of high precision magnetic measuring instruments developed abroad have been applied in various fields.Among them,the optical pump magnetometer is emerging in the field of weak magnetic measurement with the advantages of fast frequency response and high sensitivity.Biomedicine has always been an important field of magnetic instrument output.By detecting the magnetic field of human body,some diseases of human body can be diagnosed at a certain level and changes of diseases can be reflected.In recent years,more and more research has been done on the application of Optical pump magnetometer to biological magnetometry.However,the research on optical pump-magnetometer started late in China.Although some achievements have been made,there is still a gap between China and other countries in the field of weak magnetic measurement such as biomedicine.Therefore,it is of practical significance and urgent need to strengthen the study of optical pump magnetometer.This article embarks from the basic physical theory of optically pumped magnetometer,work with alkali metal cesium atoms as the magnetometer element,a vertical cavity surface emitting laser instead of traditional gas discharge light source,using the analysis of the characteristics of optical signal to complete the design of selfexcited magnetometer feedback,managed to set up autonomous cesium atom laser light pump magnetometer and complete the performance test and analysis.In this paper,a double-channel constant current source driver is designed for the driving condition of 894.6nm laser output,which can simultaneously stabilize the current output of 1.2m A and 150 m A.At the same time,according to the working temperature requirements of cesium atoms in the magnetometer,A non-magnetic heating system based on water heating is designed.This system can make the steady-state error of air chamber temperature within 0.02? in the set temperature range from 30? to 45?.According to the gas chamber specifications,a non-magnetic heating chamber was designed in accordance with the water heating mode.Through the numerical analysis and experimental verification of the thermal performance of the chamber,it was proved that the heating chamber has good thermal insulation and can heat the air chamber uniformly.Secondly,Helmholtz coil is used to establish the magnetic field to be measured by magnetometer,and the accuracy and stability of the magnetic field to be measured are verified by theoretical calculation and experimental measurement.Finally,the selfexcited cesium atom laser optically pumped magnetometer was integrated,which was placed in the magnetic field to be tested for debugging and performance testing.Through the analysis of magnetic field measurements and theoretical values,it is proved that the self-excited cesium atom laser optically pumped magnetometer can detect the magnetic field from 44?T to 89?T without magnetic shielding,and its highest resolution is 1.143?T.