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题名: 原子力显微镜光电信号处理技术研究
其他题名: Study on Opto-electronic Signal Processing in Atomic Force Microscopy System
作者: 鲁鹏
导师: 董再励
分类号: TN911.74
关键词: 高速信号处理 ; 小信号处理 ; FPGA ; 四象限探测器
索取号: TN911.74/L84/2011
学位专业: 计算机技术与应用
学位类别: 硕士
答辩日期: 2011-05-27
授予单位: 中国科学院沈阳自动化研究所
学位授予地点: 中国科学院沈阳自动化研究所
作者部门: 机器人学研究室
中文摘要: 21世纪是纳米科技的时代,如今全球各国都将纳米技术研究作为国家发展战略,纳米技术无疑将带来社会和经济的巨大发展。纳米科技的研究需要借助各种观测和操作工具,原子力显微镜(Atomic Force Microscopy, AFM)是其中应用最广泛的一种。AFM除了能够在常态下实现对原子、分子尺度大小物体的观测,并且由于其超高的分辨率和运动精度,可控、可重复的运动方式,独特的机械力作用机理,任意环境的可适应性而广泛应用于纳米观测和操作领域。 虽然具备了如此多的优点,但是AFM在扫描图像时在精度和速度上有很多限制:由于背景光和电磁辐射等因素的干扰,使AFM的检测精度受到影响而无法精确分辨出样品表面的轻微起伏变化;由于反馈速度的影响导致扫描速度慢,无法对探针样品间的作用力实现精确控制,无法有效的保护探针和样品,从而造成图像精度不高。因为上述问题的限制,导致了在理论上本应有原子级成像精度的大多数AFM系统却很难成出一幅清晰的原子排列图像。 本文针对上述问题,以自主研发的操控型原子力显微镜系统为平台,从光电传感器检测原理出发,综合小信号处理,FPGA和高速数据处理技术,进行了以下工作: l    光电传感器信号检测原理和噪声研究。对原子力显微镜中探针悬臂梁微位移检测单元中的光电传感器位置检测原理进行探讨,并分析影响其检测精度的各种因素和处理方法。 l    设计原子力显微镜成像过程中象限探测器信号处理方案。提出了在接触模式下扫描采用调制激光的方法提高接触模式下的扫描精度。依据原子力显微镜常用扫描模式下的光电传感器输出信号的共性与差异,设计出一套同时兼容两种模式并且保持检测精度和反应速度的光电信号处理方案,并且确定了DSP和FPGA相结合的双处理器系统。 l    设计小信号放大及数据采集和反馈电路。依据设计好的信号处理方案,设计信号处理的硬件系统。包括光电传感器的前置放大电路和反馈控制系统中模数混合设计及数字控制核心相关设计。 l     信号处理方案的FPGA实现。针对设计好的信号处理方案设计相应的数字算法,包括FIR滤波器算法和振幅检测算法,实现了大数据量高速信号的采集与处理。并且根据信号处理方法设计FPGA的逻辑实现以及相关接口的实现,包括模数转换器接口、数模转换器接口、与DSP通信的通用存储器接口(EMIF)等。 对系统进行综合测试,不仅能够实现对于两种扫描模式的兼容,而且支持在线调整扫描参数和手动操作等附加功能,最后进行实验,取得了初步的成果。
英文摘要: The 21st century is the era of nanotechnology, nowadays every country over the world has been arranged the nano research as a national development strategy, which will bring enormous social and economic developments. Nanotechnology research needs a variety of observations and operational tools, and atomic force microscopy (AFM) is the most widely used in nano-observation. Taking advantage of its probe based imaging in observing objects with ultra high resolution and precision, AFM has the potential as a nanomanipulation and imaging tool to assemble devices on the nanometer scale. Although the advantage of AFM is obvious, there are some restrictions of its imaging: because of the background light and electromagnetic interference (EMI), the probe’s slight deflection cannot be detected accurately; slow feedback speed makes the interaction force between the tip and sample uncontrollable, which leads to the low imaging precision and abrasion of the tip. Because of the issues above, it is very hard to image atomic, though AFM can reach an accuracy of 0.1 nano-meter theoretically. In this research, based on the principle of sensor detection, the techniques of digital signal processing, FPGA and high-speed realtime signal processing technology, several critical and challenging problems have been studied. The principle of sensor detection and the noise has been studied. The photoelectric detection principle of four quadrant detector was introduced in this paper, and the noise affecting imaging is researched.   The four quadrant detector signal processing scheme is designed. Sine-wave light intensity modulation mode laser is used in AFM’s contact mode to improve the imaging accuracy. A signal processing method which supports the contact mode and tapping mode can both increase the feedback speed and improve the precision. DSP and FPGA are used in this system. The hardware for data collection and control system are designed. According to the scheme, hardware is proposed including a pre-amplifier circuit which can improve signal-to-noise and circuit of control system. Algorithms is designed and analyzed. A FIR digital filter and sine-wave amplitude detection algorithms is designed. The interfaces between FPGA to the digital - to - analog converter, analog - to - digital converter and Texas Instruments TMSC6000 DSP platform were designed. The system was tested, which can both work in contact mode and tapping mode. Adjusting parameters online and manual operation are supported.
语种: 中文
产权排序: 1
内容类型: 学位论文
URI标识: http://ir.sia.cn/handle/173321/9411
Appears in Collections:机器人学研究室_学位论文

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Recommended Citation:
鲁鹏.原子力显微镜光电信号处理技术研究.[硕士学位论文 ].中国科学院沈阳自动化研究所 .2011
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