【作者】 张廷凯；

【导师】 张鸿海； 甘志银；

【作者基本信息】 华中科技大学 ， 机械制造及其自动化， 2009， 博士

【摘要】 原子钟是精确的计时工具,在天文、航空航天、卫星导航和物理科学等方面扮演重要角色,但由于其体积较大,在很大程度上限制了其应用的范围。实现原子钟的微型化能够拓展原子钟在不同行业的应用,扩大原子钟的应用领域,将会带来积极的社会效益和经济效益。因此,微型化原子钟成为近几年各国研究的一个热点。本文围绕微型原子钟,开展了对微型原子钟物理机理、设计方法和制作工艺的研究。在相干布局数囚禁(CPT:Coherent Population Trapping)物理机理的基础上,研究CPT原子钟的频率控制系统。从物理机理上建立原子钟的频率控制系统模型可以实现对原子钟计时性能更深入的认识,对于指导原子钟的设计实践具有重要的意义,基于物理机理建模的难点是建立原子钟物理系统的数学模型。本文首先在CPT共振方程的基础上,研究激光调制方式下的CPT共振机理,可以得到用调制频率(即计时输出频率)描述的CPT共振方程;进而研究根据CPT谱线实现原子钟锁频的数学过程,并通过对激光调制过程中物理鉴频系统的信号流分析得到物理系统的鉴频模型。最后根据原子钟的系统组成到出原子钟系统的频率控制系统模型。在此基础上进一步研究频率控制系统的不同设计和实现方案,以及用频率控制模型研究原子钟长期稳定度和短期稳定度的方法。原子钟微型化的关键是其中物理部件——碱金属蒸汽腔——的微型化,本文在介绍芯片级原子钟的基础上,进一步讨论原子钟微型化制作工艺方面的共性基础问题,包括材料选择、加工工艺、封装方法等。研究了实现物理系统微型化的各种工艺方法的特点和可行性。最后,基于MEMS技术的工艺方法,设计制作小型化原子钟物理系统。为了提高碱金属蒸汽腔的制作水平,深入研究了实现基于玻璃—硅—玻璃结构的碱金属蒸汽腔封装制作的MEMS键合工艺——阳极键合。根据玻璃的导电性质,研究键合过程电流特性,得到了不同键合条件下的电流分析和比较的数学模型。基于价键理论,建立了阳极键合的机理模型,进一步得到键合过程的外电路电学特性与键合质量的内在关系。基于上述两点,建立了不同键合条件下键合质量比较的分析模型。结合成键理论,详细讨论了阳极键合新型操作方法——两电极法多层阳极键合——的键合机理,并解释了键合过程中特殊现象——电流脉冲——的产生机制。开展了相关实验研究。最后介绍了微型原子钟物理系统制作实践过程中涉及的一些问题,并提供了相应解决策略;简要介绍了基于MEMS技术制作的小型CPT原子钟的原理样机。更多还原

【Abstract】 As precise timekeeper, atomic clock can play an important role in defferent fields such as astonomy, aerospace, navigation and physics. But it is not used widely until now for its big volume. The miniaturization of atomic clock will helpful to enlarge the application fields of atomic clock, and then will bring deep influence on the world in both society and economy. So the miniature atomic clock is becoming the research direction of atomic clock in recent years. In this dissertation the author has studied the principle, design and manufacture about miniature atomic clock.The control model of atomic clock is deduced on the base of coherence population trapping (CPT). Control model base on physical principle would be much useful in the realization of atomic clock, but be difficult in modeling of physical package. Base on the resonance equation of CPT, the equivalent equation as a function of modulating frequency is deduced from the modulation process. The method for locking frequency according to CPT line is studied. The model of frequency detection for physical package is attained according to analysis the course of detection. Then base on the construction of atomic clock the frequency control model is obtained and then different design methods are studied. The methods for studying long term stability and short term stability of atomic clock on the base of control model are studied simultaneously.The concept of chip-scale atomic clock is introduced, the common foundations of miniature atomic clock such as material, manufacture and package are discussed. The technologies for realization of miniature physical package are studied. Base on MEMS technologies some relevant practical works for miniature physical package are performed.Anodic bonding, the MEMS technology for realization of alkali vapor cell with a structure of glass-silicon-glass is studied deeply. The source of current during anodic bonding is explained and the theoretical model for forecasting bonding result is presented. According to the electric character of glass, the character during anodic bonding is studied and the model for analyzing and comparison of currents under different conditions such as temperature and applied voltage is obtained. The physical model for anodic bonding is constructed base on valence bond theory, and the essence relationship between bond result and circuit character is obtained. Base on the above two results, analytical model for bond result under different conditions is obtained. The bonding course of innovation operation of anodic bonding, multi-stick anodic bonding using two electrodes is studied on the base of valence bond theory, the reason for current spike during bonding is given. Relevant experimental studies are performed.Some relevant problems in the course of experiment are discussed. Prototype of miniature atomic clock made by MEMS technology is introduced chiefly.更多还原