Investigation On The Atomic Magnetometer

The detection of weak magnetic field has significant applications in many areas such as medical treatment, military technology, geophysical research, industrial detection and so on. In this thesis, a highly sensitive atomic magnetometer is investigated and demonstrated experimentally, whose principle is analyzed theoretically.In chapter 1, the investigation background and its significance are briefly introduced, which includes the applications of weak magnetic field detection, the description of some sensitive magnetometers and the trend of their development, and the significance of independent R&D of magnetometers which are on demand. Meanwhile, the main objective of investigation on a high performance magnetometer is also suggested.In chapter 2, the basic principle of a new type atomic magnetometer is explained theoretically by calculating the interaction between atoms and laser in a magnetic field. First, the characteristics of rubidium, Zeeman Effect and optical pumping process are introduced. Then by use of the Schrodinger Equation, the interaction process between atomic state vector and magnetic field and the theoretical expression of the relationship between transmitted laser power and magnetic field are calculated. Finally, the curve feature corresponding to the expression is analyzed and a basic way to develop an atomic magnetometer is also put forward.In chapter 3, the main structure of the experimental setup of the atomic magnetometer is presented which includes the laser source, magnetic sensor and signal detection devices. In the laser source unit, a circularly resonant laser beam is generated by precisely parameters adjusting and wavelength locking. Then in the magnetic sensor unit, sufficient rubidium atoms are provided to interact with laser in the magnetic field by adjusting the temperature. Finally, in the signal detection part, the external magnetic field is obtained by use of photodiode detection and computer signal process.In chapter 4, the performance test, simulate magnetic field measurement and result analysis of the experimental setup are presented. First, the theoretical result of the relationship between transmitted laser power and magnetic field matches well with the experimental result. Then a good outcome is achieved by simulate measurement and performance test. Finally, some factors which may affect the sensitivity of the atomic magnetometer are revealed, and meanwhile the ways of how to improve its performance in the future are also discussed.In chapter 5, a summary of the whole works is given and the outlook of such a sensitive atomic magnetometer which has much widely applications is given.