基于激光泵浦的钾光泵磁力仪关键技术研究

The prerequisite of underwater robot with high precision geomagnetic navigation is acquiring the marine magnetic field accurately. However, the resolution of existing marine magnetometers can not meet the requirements of high precision navigation system for deep sea because of some drawbacks such as poor monochromaticity, low light intensity of gas discharge lamp and spectral overlap of resonant vapor. In light of this, this project focuses on the basic mechanism of impact between potassium atoms and laser light in magnetic environment to establish a potassium magnetometer basing on laser pumping, which is expected to achieve magnetic measurement sensitivity of 0.001nT/√Hz. Magnetic measuring principle is analysed based on Zeeman effect, laser pumping and magnetic resonance. The movement mechanism of potassium atoms in magnetic environment and the angular correlation of magnetic resonance signal are researched in order to reveal the influence mechanism between laser parameters and magnetic measurement sensitivity and signal-to-noise ratio. The influence mechanism between Zeeman effect of potassium atoms with hyperfine structure and magnetic resonance signals are researched to establish the magnetic measurement model that can be used in wide range. Digital signal detection system contains laser frequency stabilization basing on modulation-free atomic dichroism, digital lock-in amplifier and particle swarm optimization for quick positioning. Magnetic measurement system noise theory is researched. In addition, blind source separation is used to analyse the error source in order to extract weak signals. All these research has great point in the improvement of high precision marine magnetometer and paves new way for high precision underwater navigation.

精确获取海洋磁场信息是水下机器人实现高精度地磁导航的先决条件。现有海洋磁力仪存在气体放电灯谱单色性差、强度低、共振元素光谱重叠等问题，磁测灵敏度难以满足深远海导航系统的要求。本项目基于激光泵浦、射频磁场对钾原子的作用机理，研究基于激光泵浦的钾光泵磁力仪，预期实现0.001nT/√Hz的磁测灵敏度。基于塞曼效应、激光光泵及磁共振研究系统磁测机理。研究钾原子在射频磁场中的运动机理及磁共振信号角相关性，揭示系统参数对磁测灵敏度、信噪比的影响机制。通过分析渐变磁场中钾原子超精细结构的塞曼效应对磁共振信号的影响机制，建立宽量程磁测模型。研究磁共振信号检测方法，主要突破基于无调制原子二向色性的激光稳频、数字锁相放大器、基于粒子群算法的磁共振点快速定位等关键技术。研究系统噪声理论，应用盲源分离分析噪声源。项目研究成果对高精度海洋磁力仪研究具有重要的理论价值，为实现高精度水下导航提供了新的技术途径。

精确获取海洋磁场信息是水下机器人实现高精度地磁导航的先决条件。现有海洋磁力仪存在气体放电灯谱单色性差、强度低、共振元素光谱重叠等问题，磁测灵敏度难以满足深远海导航系统的要求。本项目基于激光泵浦、射频磁场对钾原子的作用机理，研究基于激光泵浦的钾光泵磁力仪。基于塞曼效应、激光光泵及磁共振研究系统磁测机理，基于光学布洛赫方程推导了测磁表达式，并分析了磁共振信号的角相关性。然后，研究了原子各塞曼子能级粒子数随时间演化的规律，并采用仿真分析系统中激光泵浦光强、失谐频率及偏振态对原子各塞曼子能级粒子数的影响机制，揭示激光器输出参数对磁测灵敏度的影响机理。研究了温度以及泵浦光强对系统信噪比的影响。分析了渐变磁场作用下，非线性塞曼效应对磁测灵敏度的影响。研究磁共振信号检测方法，搭建了数字化磁共振信号的检测系统。主要突破基于无调制原子二向色性的激光稳频、数字锁相放大器、基于粒子群算法的磁共振点快速定位等关键技术。研究系统噪声理论，应用盲源分离分析噪声源。研制的基于激光泵浦的钾光泵磁力仪原理样机磁测灵敏度0.8pT•Hz-1/2。项目研究成果对高精度海洋磁力仪研究具有重要的理论价值，为实现高精度水下导航提供了新的技术途径。