Development of an atomic force microscope operating in DC non-contact mode

开发以直流非接触模式运行的原子力显微镜

基本信息

批准号：
07650066
负责人：
KIKUTA Hisao
金额：
$ 1.15万
依托单位：
OSAKA PREFECTURE UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

The purpose was development of atomic force microscope operating in DC non-contant mode. In beginning, I have made a force feedback system with a seesaw shape lever. The lever deflection was detected by an optical lever method. The sensitivity of force measurement was -10^<-10>N.However the complex structure of the seesaw lever has caused intolerable thermal drift and a low frequency response. To overcome these problems, a novel force-feedback system using a micro-cantilever commercially available was proposed.Since the cantilever deflection is detected by a simple optical fiber interferometer, the thermal drift is reduced. And the high resonant frequency of the micro-cantilever allows the high-speed scanning of samples. The optical fiber end was coated by gold thin film. The electrostatic force between the fiber end and the gold coated micro-cantilever is balanced with the atomic force between the probe tip and sample.Some force curves were measured by using this force feedback system … More . The curves were quite different from those of conventional method in which the interaction force is determined from cantilever deflection without feedback system. Especially the maximum of the attractive force in approaching was in the same order of the maximum in going back. The stability of the system was improved, so that the force resolution was -10^<-11>N.However the frequency response was still poor because the control system used for the measurement was poor. Then I could not obtain an AFM images by scanning the sample surface.A discussion to design the feedback control system with a high frequency response was made. A simple dynamic model of cantilever was proposed in case that the probe tip was in the field of interaction force. Supposing a PID controller, the control parameters were estimated to realize the high frequency response of the feedback system.A simulation result shows a possibility of frequency response of higher than 1kHz. I will actually make the controller and will attempt to operate the AFM with non-contact DC mode. Less

目的是开发在直流非恒定模式下运行的原子力显微镜。首先，我制作了一个带有跷跷板形状杠杆的力反馈系统，通过光学杠杆方法检测杠杆的偏转。力测量的灵敏度为-。 10^<-10>N。然而，跷跷板杆的复杂结构导致了难以忍受的热漂移和低频响应，为了克服这些问题，提出了一种使用市售微悬臂梁的新型力反馈系统。悬臂通过简单的光纤干涉仪检测偏转，减少了热漂移，并且微悬臂梁的高谐振频率允许高速扫描光纤端部镀有金薄膜的静电力。光纤末端和镀金微悬臂梁与探针尖端和样品之间的原子力保持平衡。使用该力反馈系统测量了一些力曲线... 更多。这些曲线与传统方法的曲线有很大不同。相互作用力特别是接近时的吸引力最大值与返回时的吸引力最大值处于同一数量级，从而提高了系统的稳定性，使得力分辨率为-10^<-11。 >N.然而，由于测量所用的控制系统较差，因此我无法通过扫描样品表面获得AFM图像，因此频率响应仍然很差。讨论了设计具有高频响应的反馈控制系统。提出了一个简单的悬臂动力学模型。假设探针尖端处于相互作用力场中，估计控制参数以实现反馈系统的高频响应。仿真结果表明频率响应可能高于1kHz。实际制作控制器并将尝试以非接触式 DC 模式操作 AFM。