新型数字式原子力显微镜的研制与应用研究

【作者】 陈英飞；

【导师】 章海军；

【作者基本信息】 浙江大学 ， 光学工程， 2005， 硕士

【摘要】 以扫描隧道显微镜(STM)与原子力显微镜(AFM)为代表的扫描探针显微镜(SPM)技术，是纳米技术发展的重要基础。其中AFM由于测量不受样品导电性的限制，具有更加广泛的应用领域。随着纳米技术的发展，仪器本身的稳定性、操作的简便性、易维护性等以及应用领域的拓展和产业化也越来越受到人们的关注。本文提出了AFM系统数字化的新思想，对其原理和方法进行了系统的理论研究，在数字式原子力显微镜的研制上取得了一系列的突破，为数字式AFM在国内的普及和产业化奠定了良好的基础。 本文在全面分析国内外AFM技术研究和应用现状的基础上，对现有AFM仪器的缺陷和不足作了比较全面的理论分析和实验研究，着重分析AFM的反馈控制规律和探针一样品的进给规律，提出了用数字PID调节器实现AFM系统的反馈控制和样品的进给由步进电机控制丝杠传动机构实现，使AFM仪器的功能、自动化和稳定性在技术上向前迈了一大步，为AFM技术能够更简单、方便、有效地应用到各个科学领域奠定了基础。 本文的工作特点和创新之处主要体现在以下几点： 1、在理论研究的基础上，提出了原子力显微镜数字化的新方法。随着全面数字化时代的到来，数字化扫描探针显微镜的研制也日益提上了进程。目前，国内SPM仪器大多还停留在模拟量控制的水平，仪器本身无法在本质上做进一步的更新。因此，为提高仪器本身的稳定性、操作的简便性以及进一步增加仪器的功能，必须在AFM系统中采用数字化技术。 2、设计完成了AFM的数字PID反馈控制系统。目前，国内原子力显微镜大多采用模拟PID控制，虽然模拟控制具有反应速度快的优点，但缺点是精度不高，抗干扰能力不强，往往会引入附加的惯性环节，且电路结构复杂。而AFM系统的工作特点即探针一样品间距的精确控制，要求有一个灵敏、高效、精确、稳定可靠的反馈控制系统。目前，AFM的数字PID控制研究虽然已取得一定的进展，但都是通过DSP实现的，这无疑提高了AFM的成本，且技术难度大、开发设备昂贵。为此，我们研制了基于计算机的数字PID控制，PID控制规律用计算机程序来实现，各种控制算法只要改变计算机程序就可实现，具有很大灵活性，一些原来在模拟PID控制器中无法实现的问题，在引入计算机以后，就可以得到解决了。且计算机原本就是AFM系统的一个重要组成部分，因此，我们不需要增加新的设备就可实现AFM的数字PID控制，这无疑降低了仪器的成本，且提高了仪浙江大学了吹_l论文器的实用化和简易化程度。 3、设计完成由步进电机控制的AFM自动进给机构及其程序的编写。计算机控制步进电机驱动器输出脉冲信号驱动步进电机转动，从而实现AFM的探针一样品自动逼近，提高了操作的简便性和系统的自动化程度。 4、研究采用了新型的PCI数据采集卡及其软件的编写。提高了AFM系统与不同计算机和不同操作系统的兼容性，为AFM的普及奠定了良好的基础。 5、拓展了AFM的扫描控制软件和图像处理软件功能。如样品图像的三维标尺添加功能、纳米粗糙度线/面测量功能、微位移测量功能等。关键词:纳米技术、原子力显微镜、数字PID控制、步进电机、进给机构、数字化、图像处理、AFM应用更多还原

【Abstract】 With the development of nano-technology, scanning probe microscopy (SPM), especially atomic force microscopy (AFM), has been the most widely demanded and applied tools for researchers to pursue more ambitious goals, and has actually become the indispensable instruments for nano-scientists and engineers. Besides the stabilization of the instrument itself, the simplicity of its operation, the easiness of maintenance, the expansion of its application sphere and the trend of it becoming an industry have aroused more and more concerns.In this thesis, a new concept of digital AFM has been put forward, and a series of breakthrough of digital AFM has been gained based on the systematic research of its principle and method, which expands AFM’s application sphere and lays good foundation for the popularization of AFM in China.On the basis of analyzing the current situation of AFM’s research and application nationally and internationally, the paper makes thorough theoretical analysis into the defects of AFM made in China. The feedback control system of AFM and the action law of tip-sample feeding mechanism are emphatically analyzed in this thesis. We developed the new method of feedback control system which is implemented by incremental PID control, while another new method of feeding mechanism which is implemented by stepper motor based on the research of approximation law of tip-sample and kinds of other feeding mechanisms, which make AFM forward a long way on the technique function, automation and stability, which will help the atomic force microscopy expediently and effectively used in various scientific areas. And the development of digital AFM not only has important theoretical significations, but also has a great prospect for practical applications.The research content and achievements of this thesis are as follows:On the basis of the theoretical researches, we developed the new method of digital AFM. With the coming of the over-all digital time, the research of digital scanning probe microscopy has become increasingly important. At the present time, most SPM in China only stay on the level of analog quantity control, which is the intrinsic reason that the instrument can’t be further refreshed. The digital technique, therefore, should be used in the AFM system, for increasing stability of the instrument itself, the simplicity of its operation, and the function of the instrument.We have constructed a digital PID feedback control system of AFM. At present, analogy PID control only with the merit of fast reaction speed, while the shortcomings are low precision, week ability of anti-interference, complex circuit construction, is widely used in most AFM in China. However a sensitive, highly active, precise, steady and reliable feedbackcontrol system is actively demanded in AFM system, recording to operating principle of AFM. Though the research of digital PID control of AFM has gain a certain development, the PID control is implemented by the technique of DSP, which not only increase the cost of AFM, but also has difficulty technique. We develop a new method of digital PID control in which AFM is implemented by the technique of computer. The control algorithms will be changed so long as change the programs in the computer, which brings a great flexibility. Some questions that aren’t settled in the analogy PID for a long time, thus can be successfully resolved. Further more, the computer is formerly a part of the AFM system, which not only reduces the cost but also enhances the instrument’s utility and simplification.A feeding mechanism, in the charge of stepper motor, adjusting the spacing interval between the sample and the tip has been accomplished. The computer is in control of the stepper motor driver to output impulse signals that are used to drive the stepper motor. The sample, therefore, is automatically moved to approach the tip, which not only enhances the simplicity of the operation, but also improves the automation of the system.A new sort of data acquisition board is used in the AFM system. And we optimized the so更多还原