深空环境频率调制原子力显微镜测量技术研究

将原子力显微镜应用于深空探测对于人类真实、准确地了解太空物质的微观形貌及性质具有重要意义。频率调制原子力显微镜（FM-AFM）工作带宽不受品质因数Q值限制，可以使用高Q值微悬臂探针，相比幅度调制原子力显微镜更适用于真空环境。现有的商品化FM-AFM不能智能操控、体积大、功耗高、需高压驱动，不能直接用于深空探测。本项目将在实验室已有基础上对FM-AFM的智能化、小型化和低功耗进行研究，包括：自主选区技术和参数自适应技术的研究，使仪器在无人值守的情况下能够自主操作；自激励模块和数字频率解调电路的研究，在保证解调精度的条件下达到电路的小型化和低功耗；探头的机械结构和材料的研究，减小其体积和重量。同时，本项目将双臂自由振动的石英音叉作为FM-AFM的力传感器，建立其双臂自由振动的机械模型，研究针尖样品相互作用力对于石英音叉振动频率的影响机制，为FM-AFM反馈控制的优化设计以及定量解释奠定理论基础

The application of atomic force microscope（AFM）in deep space exploration will be of great significance to understand the microstructure and the properties of the space substances. The imaging quality of frequency-modulation atomic force microscopy (FM-AFM) will not be influenced by the value of Q. So it works better than Amplitude modulation atomic force microscope in vacuum environment. The existing FM-AFM in the market have many defects, such as lacking of intelligence operation, over-sized equipment volume, high energy consumption and high voltage driving, etc, that it can not be directly used for the measurement in deep space environment. Based on our previous research，we focus on the research of intelligent, miniaturization and low power frequency modulated AFM in this project. It includes: the development of auto-zoom technology and parameters adaptive technology to make the instrument operate autonomously in unattended environment, research of self-excitation module and digital frequency demodulation circuit. The circuit will be miniaturized and lowered power consumption under the premise of guaranteeing the demodulation accuracy .The volume and weight of the detector will be reduced with improved mechanical structure and material. Meanwhile, the quartz tuning fork is used as force sensors in FM-AFM. The introduction of a mechanical model of the quartz tuning fork can be used to optimize the design of the feedback control of atomic force microscope and to establish the foundation for quantitative interpretation of the experimental results.