A calibrated atomic force microscope using an orthogonal scanner and a calibrated laser interferometer

A compact and two-dimensional atomic force microscope (AFM) using an orthogonal sample scanner, a calibrated homodyne laser interferometer and a commercial AFM head was developed for use in the nano-metrology field. The x and y position of the sample with respect to the tip are acquired by using the laser interferometer in the open-loop state, when each z data point of the AFM head is taken. The sample scanner, which has a motion amplifying mechanism was designed to move a sample up to 100 μm × 100 μm in orthogonal way, which means less crosstalk between axes. Moreover, the rotational errors between axes are measured to ensure the accuracy of the calibrated AFM within the full scanning range. The conventional homodyne laser interferometer was used to measure the x and y displacements of the sample and compensated via an X-ray interferometer to reduce the nonlinearity of the optical interferometer. The repeatability of the calibrated AFM was measured to sub-nanometers within a few hundred nanometers scanning range.     

原子力显微扫描云纹法的相移技术研究

提出一种原子力显微镜扫描云纹法的相移新技术 ,运用原子力显微镜的压电扫描头作为相移元件 ,对所得云纹图像可进行 0 - 2 π范围内的四步相移。对该方法的测量原理和实验技术进行了详细的阐述。作为典型实验和应用实例 ,分别对由全息光栅和含热变形的电子封装试件栅形成的云纹进行相移分析。成功的实验结果表明 ,该方法是可行的 ,为微米云纹方法的条纹处理提供了一种新途径。该方法可望在微观变形的云纹法测量中发挥积极作用     

原子力显微镜的压电陶瓷非线性及图象畸变的校正

研制了卧式原子力显微镜(AFM)系统,讨论压电陶瓷的非线性及AFM图象畸变的软件校正方法.提出利用光束偏转法精确测定XY扫描器压电陶瓷的伸长量与控制电压之间的相互关系,得到压电陶瓷的非线性曲线;根据非线性的偏离程度,通过扫描软件对X和Y方向的扫描电压作逐点补偿,据此有效地校正图象畸变.并给出分别用未校正软件与校正软件扫描获得的部分样品的AFM图象.     

Double-reflection polygon mirror for high-speed optical coherence microscopy

We report on a high-speed, high-efficiency, high-duty-cycle, path-length-maintaining and linear beam scanner suitable for en face scanning optical coherence microscopy. Fast transverse beam scanning is achieved by use of a double-reflection polygon mirror (DRPM) rotating at a constant speed. With a motor speed of 18,000 rpm and a scanner diameter of 50 mm, the DRPM provides a line rate up to 3 kHz, +/-1.8 degrees scanning range, and 90% duty cycle. A much higher scanning speed and much larger scanning range can be readily achieved by increasing the scanner diameter.     

Atomic force microscopy studies of chemical–mechanical processes on silicon(100) surfaces

Atomic force microscopy (AFM) is used to examine chemical–mechanical processes on Si(100) surfaces. The AFM tip serves as a single asperity contact to exert tribological forces as well as an imaging tool. By scanning in chemically aggressive solutions, material removal can be observed directly. In the silicon system, high-force scans are used to remove oxide and initiate etching in selected locations, followed by low-force scans to image the resulting surfaces. Material removal rates were measured as a function of applied load, number of scans, solution composition, and time. In basic solution, places where the underlying silicon is exposed etch rapidly, producing structures 100 nm or less in size. Although the surface roughness initially increases during etching, the final surfaces are smooth. The oxide is extremely sensitive to applied stress: even very light scanning accelerates oxide dissolution. Once the oxide is removed, chemical etching proceeds through the underlying silicon with or without AFM scanning; but the silicon etches more rapidly if AFM scanning is continued, due to true chemical–mechanical (tribochemical) effects.     

双探头三维表面轮廓测量系统

提出了一种将原子力显微(AFM)探头与位置敏感探测器测距探头相结合的双探头三维表面轮廓测量新方法, 可在获取样品表面轮廓的同时, 测定样品局部形貌。搭建了双探头三维表面轮廓测量系统, 阐述了系统的工作原理, 并对其结构组成包括双探头、步进扫描台和计算机控制平台进行了说明。用2000 line/mm的光栅进行了扫描实验, 对系统的测量范围进行了标定。以外径8 mm、内径4 mm的金属垫圈为样品, 进行了整体三维表面轮廓与局部表面形貌测量实验, 给出了垫圈表面图和局部三维形貌图。结果表明, 该系统能满足不同尺寸和材质的样品的测量要求, 即可实现对样品轮廓的大范围扫描测量, 又可对样品局部进行高精度形貌测量。     

基于快速扫描光学延迟线谐振扫描的相位调制方法

提出利用快速扫描光学延迟线(Rapid Scanning Optical Delay Line,RSOD)作为光学相干层析成像(Optical Coherence Tomography,OCT)系统的相位调制器,并采用正弦驱动方式(谐振扫描)来提高扫描频率,进而实现高频相位调制的方法.介绍了基于RSOD相位调制器的干涉信号包络解调方法,分析了大振镜低频率线性驱动、小振镜高频线性驱动和大振镜高速正弦驱动三种实施方案对OCT性能的影响,并针对谐振扫描方案中轴向扫描的非线性提出了图像畸变定量校正的方法.结果表明:RSOD大振镜谐振扫描的模式能够兼顾系统成像速度、成像范围以及系统信噪比的要求,是一种行之有效的相位调制方法.     

碳纳米管的可控长度拾取及导电性分析

拾取指定长度的半导体性碳纳米管对大规模制造碳纳米管场效应管具有重要意义.本文提出了一种利用原子力显微镜探针和钨针对碳纳米管进行可控长度拾取的方法并进行了碳纳米管导电性分析.在扫描电子显微镜下搭建微纳操作系统,针对切割操作过程中原子力显微镜探针、钨针和碳纳米管的接触情况进行了力学建模和拾取长度误差分析.建立了单根金属性碳纳米管、单根半导体性碳纳米管及碳纳米管束与钨针接触的电路模型,推导了接入不同性质碳纳米管后电路的电流电压特性方程.使用原子力显微镜探针对碳纳米管的空间位姿进行调整,控制钨针对碳纳米管上目标位置进行通电切割,同时获取切割电路中的电流电压数据.实验结果表明,本文提出的方法能够有效控制所拾取碳纳米管的长度,增加碳纳米管与原子力显微镜探针的水平接触长度能够减小碳纳米管形变导致的拾取长度误差,建立的电流电压特性方程能够用于分析碳纳米管的导电性.     

Scanning tunnelling microscopy imaging and modification of hydrogen-passivated Ge(100) surfaces

Scanning tunnelling microscopy (STM) study and modification of hydrogen (H)-passivated Ge(100) surfaces have been investigated. Thermal oxidation procedures were used to minimise surface roughness. Ge samples were passivated in HF solution after thermal oxidation. STM and atomic force microscope (AFM) imaging showed that, using HF etching after thermal oxidation, we can obtain a natural H-passivatedtopographically and chemically flat Ge(100) surface. The root-mean-square (rms) roughness ofa H-passivatedGe(100) surface measured both by STM and AFM is less than 2 ?. Electric properties of H-passivatedGe(100) surfaces were studied by scanning tunnelling spectroscopy (STS) in nitrogen ambient. STS showed that the H-passivated Ge surfaces were not pinned. Modification on H-passivated Ge(100) surfaces was carried out using STM by applying an electric voltage between the sample and tip in air. Modified features were characterised by STM and AFM imaging. On the H-passivated Ge(100) surfaces, stable, low-voltage, nanometer-scale modified features can be produced.     

Large depth-of-view portable three-dimensional laser scanner and its segmental calibration for robot vision

A portable 3D laser scanning system has been designed and built for robot vision. By tilting the charge coupled device (CCD) plane of portable 3D scanning system according to the Scheimpflug condition, the depth-of-view is successfully extended from less than 40 to 100 mm. Based on the tilted camera model, the traditional two-step camera calibration method is modified by introducing the angle factor. Meanwhile, a novel segmental calibration approach, i.e., dividing the whole work range into two parts and calibrating, respectively, with corresponding system parameters, is proposed to effectively improve the measurement accuracy of the large depth-of-view 3D laser scanner. In the process of 3D reconstruction, different calibration parameters are used to transform the 2D coordinates into 3D coordinates according to the different positions of the image in the CCD plane, and the measurement accuracy of is obtained experimentally. Finally, the experiment of scanning a lamina by the large depth-of-view portable 3D laser scanner used by an industrial robot IRB 4400 is also employed to demonstrate the effectiveness and high measurement accuracy of our scanning system.     

A study of AFM-based scratch process on polycarbonate surface and grating application

We report on the possibility of applying atomic force microscope (AFM) lithography to draw micro/nano-structures on the surface of a polycarbonate (PC) substrate. We also fabricated a grating structure on the PC surface using the scratch method. An AFM silicon tip coated with a diamond layer was utilized as a cutting tool to scratch the surface of the sample. In order to obtain pattern depth deeper than the control method of interaction force, we used a scanner movement method which the sample scanner moves along the Z-axis. A grating of 100 μm × 150 μm was fabricated by the step and repeat method wherein the sample stage is moved in the direction of the XY-axis. The period and the depth of the grating are 500 and 50 nm, respectively. Light of 632.8 nm wavelength was diffracted on the surface of the PC substrate.     

新型光波导阵列电光快速扫描器的光波导效应

对新型光波导阵列电光快速扫描器中的光波导效应进行了研究,分析了考虑光波导模式效应的光波导阵列电光快速扫描器的扫描特性,指出光波导模式特性主要影响新型光波导电光快速扫描器的扫描范围和效率,并研究了在应用该器件进行光束扫描时的技术要求.     

基于IEC标准的日本滨松SHR22000全身用PET扫描仪性能测试

SHR22000是日本滨松光子学株式会社开发的人体全身用正电子发射断层扫描仪. 扫描仪具有32层探测器环, 二维采集可形成63个切片, 病人孔径为60cm, 单个体位数据采集时间为3—5min.扫描仪的轴向视野为22.5cm, 经5个体位可以完成全身扫描, 视野中轴10mm处平均横向分辨率可达到3.2mm. 本文依照国际标准IEC 61675-1(亦即GB/T18988.1-2003)规定的各项指标对该扫描仪的空间分辨率、灵敏度、散射和计数率特性以及复原系数进行了测试, 并给出结果数据.     

衍射光学二维激光扫描器设计制作研究

提出、设计并采用激光直写和反应离子刻蚀技术制作出一种新型的衍射光学纯相位型二维激光扫描器,并进行了系统参数的实验测试,其扫描角度为２５°×２５°,衍射效率为４１％。     

Rayleigh instabilities in multiply charged sodium clusters

The stability of multiply charged sodium clusters Na(q+)(n) (q< or =10) produced in collisions between neutral clusters and multiply charged ions A(z+) ( z = 1 to 28) is experimentally investigated. Multiply charged clusters are formed within a large range of temperatures and fissilities. They are identified by means of a high-resolution reflectron-type time-of-flight mass spectrometer (m/deltam approximately 14 000). The maximum fissility of stable clusters is obtained for z = 28 and is X approximately 0.85+/-0.07, slightly below the Rayleigh limit (X = 1). It is mainly limited by the initial cluster temperature (T approximately 100 K).     

光学显微镜与CCD监视器组合的原子力显微镜

研制了一种与光学显微镜结合并配置 CCD 监视器的原子力显微镜,可同时获得样品的原子力显微镜图象及光学图象.已能分辨出5纳米的精细结构,最大扫描范围可达2μm.文中给出了本仪器获得的一些样品图象结果.     

Comparison of fractal analyses methods and fractal dimension for pre-treated stainless steel surfaces and the correlation to adhesive joint strength

The fractal dimensions of six differently mechanically pre-treated stainless steel samples were investigated using five fractal algorithms. The surfaces were analyzed using a profiler, atomic force microscopy (AFM), scanning electron microscopy (SEM) and light microscopy (LM), and thereafter adhesively bonded and tested in single-overlap joints to test their tensile strength. All samples showed different fractal behavior, depending on the microscopic methods and fractal algorithms. However, the overall relation between fractal dimension and tensile strength is qualitatively the same, except for the SEM images. This verifies that tensile strength is correlated to fractal dimension, although only within the length-scale of the profiler and the light microscope (≈0.5–100 μm). The AFM method was excluded in this comparison, since the limitation in the z-direction for the AFM scanner made it difficult to scan the rougher parts of the blasted samples. The magnitude of the surfaces is a parameter not often considered in fractal analysis. It is shown that the magnitude, for the Fourier method, is correlated to the arithmetic average difference, R_a, but only weakly to the fractal dimension. Hence, traditional parameters, such as R_a, tell us very little about the spatial distribution of the elevation data. Received: 22 December 1999 / Accepted: 9 October 2000 / Published online: 9 February 2001     

High-speed atomic force microscopy with phase-detection

In order to improve the scanning speed of tapping mode AFM, we have studied the phase-detection mode AFM with a high frequency (1.5 MHz) cantilever. The phase shifts versus tip-sample distance with different types of samples including polymer, semiconductor, and graphite were measured and the interaction forces were analyzed. It was found that the phase shift in repulsive region is nearly linear as a function of distance, which can be used for feedback control in general, except that some blunt tips cause reversed polarity of phase shift due to excessive energy dissipation. High-speed image with scan rate of 100 Hz was obtained which were controlled with phase shift as a feedback signal.     

二维计算全息激光扫描器

本文讨论了计算全息激光扫描器的基本原理,详细推导出平移型二维等间距线阵扫描器的位相函数表达式和平移型二维抛物线扫描器的位相函数表达式。本文还详细介绍了上述二种扫描器的制作方法,并给出实验结果。对于等间距线阵扫描器,作者提出了一种简单易行的制作方法。     

Examination of the developed scanning system for red-green-blue laser projector with a feedback control

The galvanometric scanning system is widely used in laser material processing and laser shows. The scanner is a broadband component, damped sufficiently to operate over a wide range of frequencies, from zero to a higher value related to its mechanical resonance. Developing a galvanometric scanner is an important issue in the design of optical systems. This study focuses on the development of the scanning system for a laser projector using red, green, and blue diode lasers. The performance of the laser projector, which consists of the scanning control system, color control system, and position detector, is also discussed.