Research On Magnetic And Gravity Field Measurement

Precision measurement of magnetic and gravity field is of great significance in both fundamental and applied science. Thanks to the rapid development of laser technology and atomic physics, scientists are able to measure the magnetic and gravity field more accurately based on the interaction between laser and atoms. This dissertation introduces the experimental research work of the author on optical pumped magnetometer and atom interferometer gravimeter.In the first chapter, the meaning of magnetic and gravity field measurement is introduced, the research background and current conditions of magnetometers and gravimeters are presented.Based on the optical detected magnetic resonance technique, the optical pumped magnetometers are capable of measuring the external magnetic field precisely. After a brief interpretation of the theoretical basis, the detailed experiment setup, including the laser system, the magnetic field system and the signal processing system will be introduced. With the optimization process, the sensitivity of 1.8pT/Hz1/2 is achieved. This part of work comprises the second and third chapters.Atom interferometer gravimeter is expeditiously developed in the recent two decades. In this kind of gravimeter, Raman pulses are adopted to manipulate the atomic wave packet and realize the atom interference consequently. Then the gravity acceleration will be extracted from the analysis of interference fringe. In chapter 4,I will start from the interaction between laser and atoms, and introduce the principle of Raman-pulse type atom interferometer gravimeter theoretically. Aiming at a compact setup of atom interferometry, in chapter 5, the several main parts of this setup, the vacuum system, the laser system, the Raman laser system, the magnetic field system, the fiber system and the measurement & control system will be presented detailedly. Then in chapter 6 I will introduce the experiment results including the realization of MOT, atomic fountain, state selection, interference result in Doppler-insensitive and Doppler-sensitive scheme. The gravity measurement resolution of 7.4×10-7g@360s is achieved.In the last chapter, the main experimental results will be summarized, and the suggestions for next step are proposed.