二维零位光栅自动纳米定位系统

搭建了能够在二维方向上实现纳米级定位的二维自动定位系统。首先,加工了栅格间距为5 μm的64×64编码的透射式二维零位光栅;然后,分析设计了光栅系统光电转换电路和数据控制电路,实现了系统数据采集、显示和运动控制等功能。在此基础上搭建了基于二维零位光栅的纳米定位系统,并利用积分法实现了二维方向的自动定位。实验结果表明,系统定位速度对透射光强分布具有很高的依赖性,系统一次定位的成功率与初始位置密切相关。若起始位置在以零位为中心,半径为2.5 μm圆形区域内,系统可实现纳米量级定位对准;当起始位置在以零位为中心,5~200 μm为半径的圆环范围内,自动定位可能存在盲点,但通过改变初始位置重新进行搜索,仍然能够准确地实现纳米定位。     

对变线距光栅干涉测量中的环形条纹的分析

变线距光栅能够自动聚焦和消像差,在同步辐射装置、激光核聚变装置上有着广阔的应用前景,本文用干涉法测量变线距光栅的密度,设计并给出了实验中的光路,发现了环形的干涉条纹和变化规律,分析了这些现象产生的原因,产生明显的环形条纹的必要条件首先是变线距光栅的线密度单调变化的,连续增加或连续减小,其次要光栅的刻线是弯的,第三虚栅的密度接近待测光栅的整数倍,由于元件位置偏差,检测用的平面波会变成球面波,也会产生环形的干涉条纹,但是这种效应可以忽略.预言了类似双曲线的干涉条纹.通过对条纹运动规律的分析,可以在初步测量中定性分析光栅密度的变化趋势,从而为进一步测量做准备.     

A nano-scale alignment method for imprint lithography

A novel nano-scale alignment technique based on moiré signal for room-temperature imprint lithography in the submicron realm is proposed. The moiré signals generated by two pairs of quadruple gratings on mold and wafer are optically projected onto two photo-detector arrays, then the detected moiré signals are used to estimate the alignment errors in the x and y directions. The experiment results indicate that complex differential moiré signal is sensitive to relative displacement of the mold and wafer, and the alignment accuracy obtained in the x and y directions and in ϑ are ±20 nm, ±25 nm and ±1 μrad (3σ), respectively. They can meet the requirements of alignment accuracy for submicron imprint lithography.     

Dynamic position measurement technique for flash-on-the-fly wafer exposure

A wafer alignment technique is described for flash-on-the-fly operation of pulsed excimer laser exposure sources. The positioning requirements of the measurement system are defined and possible alignment patterns are discussed. A chevron grating is proposed as the basic measuring element and a ‘zeroth’ layer reference was used to improve image contrast. An array of etched pits bounded by the (111) crystal planes of the silicon wafer formed the reference pattern. Experimental results confirm that chevron gratings are a viable means of deriving alignment signals from wafers and the etched pit reference pattern gave good contrast throughout the process steps.     

莫尔信号传感器光栅倾斜角度对精密定位准确度的影响

介绍利用激光干涉莫尔信号的精密定位方法,给出激光莫尔信号传感器光栅设定角度误差时的莫尔信号位移特性,以此说明了光栅设定的角度倾斜如何影响精密定位装置的定位准确度。     

云纹法检测变线距光栅的线密度

变线距光栅在同步辐射装置、激光核聚变装置上有着广阔的应用前景,它的制作和检测方法尚未成熟,本文在介绍变线距光栅线密度变化规律的基础上,采用级数形式表达变线距光栅线密度,比较了几种测量方法后,将云纹法引入变线距光栅的检测中,从理论上介绍了几何云纹法和云纹干涉法,几何云纹法适合于线密度很低的光栅,云纹干涉法适合于线密度较高的光栅,云纹的密度反映了光栅的线密度,如果云纹非常密,精确地测量所有云纹的坐标比较难,可以用数云纹数目的方法测出光栅的密度变化,就变线距光栅的检测分别给出了有关理论公式,并给出实际测量中的光路和初步的结果,最后指出这种方法可以用在变线距光栅的加工中.     

基于激光莫尔信号精密定位装置的精度提高

为提高基于激光莫尔信号精密装置的定位精度 ,本文探讨了激光束束径与激光莫尔信号的依存关系 ,给出了与光栅衍射缝隙条数相对应的最小激光束束径的大小。其次还说明了激光源的光强度变化对精密定位装置的定位精度影响     

Efficiency of 2D alignment methods

In single particle analysis, the alignment of two-dimensional images is a fundamental step aimed at bringing into register various particle views of biological macromolecules observed with the electron microscope. The computational efficiency of this step is a deciding factor in design of alignment strategies for large sets of noisy data and in development of three-dimensional structure refinement methods. In addition, the accuracy of the alignment method varies depending on the numerical solutions adopted to efficiently perform exhaustive searches for three orientation parameters. The selected alignment methods are analyzed in terms of their computational complexity and the estimates of numbers of arithmetic operations for each method are given. The tests of alignment accuracy are performed using images simulated in accordance with the linear theory of image formation in the electron microscope. It is demonstrated that the efficiency of the alignment methods can be improved if approximate centers of gravity of particle views are known. The accuracy of the methods considered is largely affected, particularly for high noise levels, by the order in which interpolation steps are applied.     

Strain sensing characteristic of ultrasonic excitation-fiber Bragg gratings damage detection technique

There are good prospects for development of ultrasonic excitation-fiber Bragg gratings (UE-FBGs) damage detection techniques in the field of Nondestructive Testing (NDT). However, corresponding strain sensing theories are few and only applicable to the embedded fiber Bragg gratings (FBGs) sensors in composite structures. First, a four-cylinder sensing model for both the embedded and glued FBG sensors is established by introducing a surface-bonded effect coefficient obtained from simulation analysis in this paper. According to the shear-lag theory, an improved strain sensing function is derived from this model by considering the contribution made by the elastic modulus of host material. Then, based on above function, the strain sensing characteristics are analyzed. Finally, the system with an ultrasonic transducer to excite FBG and a demodulation device employing a tunable laser to detect FBG wavelength shifts was established to validate the theoretical analysis. The experiment results showed that the ultrasonic strain sensing ability of the FBG sensor decreased with the increase of ultrasonic frequency and glued thickness.     

Cryo-EM image alignment based on nonuniform fast Fourier transform

In single particle analysis, two-dimensional (2-D) alignment is a fundamental step intended to put into register various particle projections of biological macromolecules collected at the electron microscope. The efficiency and quality of three-dimensional (3-D) structure reconstruction largely depends on the computational speed and alignment accuracy of this crucial step. In order to improve the performance of alignment, we introduce a new method that takes advantage of the highly accurate interpolation scheme based on the gridding method, a version of the nonuniform fast Fourier transform, and utilizes a multi-dimensional optimization algorithm for the refinement of the orientation parameters. Using simulated data, we demonstrate that by using less than half of the sample points and taking twice the runtime, our new 2-D alignment method achieves dramatically better alignment accuracy than that based on quadratic interpolation. We also apply our method to image to volume registration, the key step in the single particle EM structure refinement protocol. We find that in this case the accuracy of the method not only surpasses the accuracy of the commonly used real-space implementation, but results are achieved in much shorter time, making gridding-based alignment a perfect candidate for efficient structure determination in single particle analysis.     

双目CCD结构光三维测量系统中的立体匹配

在立体视觉中,比较了几种常见立体匹配方法,并针对存在的问题,提出了多种方法融于一体的高效立体匹配方法.首先将计算机构造的用于解相的光栅由投影仪投射到物体上,再将计算机构造的一系列黑白相间的编码光栅也由投影仪投射到物体上;然后将畸变栅线图像由摄像机采集到计算机中,用解相光栅进行解相得到折叠在[-π,π]区间内的相主值,用所述结构光编码方法进行相展开得到相位的周期,二者相加得到真实相位值.利用插值算法将具有相同相位的点拟合成连续曲线,从而实现了两幅CCD图像相同相位曲线的匹配,再根据外极约束条件,得到两幅图像点的匹配.在反向工程中,用该方法对电话接线筒进行三维测量,实验验证了该方法进行立体匹配的高效性和准确性.     

基于啮合特性直齿锥齿轮分支传动静力学均载分析

为了改善直齿锥齿轮分支传动系统性能,提出基于啮合特性的静态均载分析方法。通过建立考虑中心轮安装误差的单级分支系统多体齿轮齿面接触分析(MTCA)方法,获得各齿轮副初始接触间隙;计及该间隙引起的啮合偏差,采用集中参数法主要考虑中心轮的浮动特性,建立考虑其支撑变形、各齿轮扭转变形相互耦合的静力学平衡方程,获得各分支均载系数,分析了载荷、安装误差、支撑刚度等对系统均载系数的影响。结果表明,随支撑刚度、安装误差的增大,均载系数逐渐增大,轴向对正误差和偏置对正误差对均载系数的影响是等效的;随转矩的增加,均载系数逐渐减小;各分支齿轮副的几何传动误差大小反映了均载系数变化规律,即齿面初始间隙越大,承担的载荷越小。研究结果为高精度直齿锥齿轮分支系统的均载分析提供了理论参考。     

MEASUREMENT OF 2-DIMENSIONAL DISPLACEMENT USING 2-D ZERO-REFERENCE MARKS

Several 2-D displacement sensing methods are reviewed. As to the cross diffraction grating, there is no absolute zero-reference. In regards to the optical fiber method, the output signal is affected greatly by the quality of the reflecting surface and it is hard to get high resolution. Considering the concentric-circle gratings, the displacement can only be gained with complicated calculating of the experiment data. Compared with the advantages and limitations of the methods above, a novel 2-D zero-reference mark is especially proposed and demonstrated. This kind of mark has an absolute zero-reference when used in pair, and the experimental result is simple to dispose. By superimposing a pair of specially coded 2-D marks, the correct alignment position of the two marks can be detected by the maximum output of the sharp intensity peak. And each slope of the peak is of good linearity which can be used to achieve high resolution in positioning and alignment in two dimensions. Design and fabrication of such     

基于光学传输矩阵的电动二维转镜读数修正

针对数字式二维转镜在光学转像时产生的转角值与实际像移不一致的问题,提出了一种运用光学矩阵修正读数误差的方法。根据二维转台对准读数检测原理建立数学模型,得出修正后的出射光线的俯仰角及方位角。为了验证上述模型的正确性,采用高精度经纬仪对修正后的出射光线方向进行校对。经实验对比,该方法在不提高加工安装精度的情况下修正了二维转镜的读数误差,其精度达到4″。     

基于平板扫描器的新型AFM系统

研制了一种基于平板扫描器的新型原子力显微镜(AFM)系统。该系统创新地把二维平板扫描器和一维反馈控制器相结合,有效地克服了传统扫描器Z向反馈控制与XY扫描平面之间的非线性交叉耦合误差,同时保证了大范围扫描时检测光路的稳定性。利用该系统与传统AFM作了氧化铝薄膜和光栅对比扫描实验,结果表明这种AFM系统能够获得无扭曲、规则的理想图像。     

基于PSD的工件自动对准系统

介绍了应用二维PSD建立的激光—PSD自动对准系统的组成、位置控制数学模型以及偏心调整机构。该系统能实现回转体类零件在工作台上的自动对准。试验表明,系统使用简单方便、精度高、可靠性好。     

基于PSD的工件自动对准系统

介绍了应用二维PSD建立的激光-PSD自动对准系统的组成、位置控制数学模型以及偏心调整机构。该系统能实现回转体类零件在工作台上的自动对准。试验表明,系统使用方便、精度高、可靠性好。     

基于二维PSD的激光准直系统研究

提出了一种以二维位置敏感传感器(PSD)作为反馈元件来实现激光光束自动准直的设计方案,同时建立了测量控制系统的数学模型。经过测试与理论分析,激光光束的准直控制范围不大于20μm,且此准直系统具有结构简单、调节快速的特点,可以广泛用于零件形位误差检测与机械安装调试过程中快速建立光学基准。     

NANOIMPRINT LITHOGRAPHY TECHNOLOGY WITH AUTOMATIC ALIGNMENT

Nanoimprint lithography (NIL) is recognized as one of the most promising candidates for the next generation lithography (NGL) to obtain sub-100 nm patterns because of its simplicity, high-throughput and low-cost. While substantial effort has been expending on NIL for producing smaller and smaller feature sizes, considerably less effort has been devoted to the equally important issue—alignment between template and substrate. A homemade prototype nanoimprint lithography tool with a high precision automatic alignment system based on Moiré signals is presented. Coarse and fine pitch gratings are adopted to produce Moiré signals to control macro and micro actuators and enable the substrate to move towards the desired position automatically. Linear motors with 300 mm travel range and 1 μm step resolution are used as macro actuators, and piezoelectric translators with 50 μm travel range and 1 nm step resolution are used as micro actuators. In addition, the prototype provides one translation (z displacement) and two tilting motion(α and β ) to automatically bring uniform intact contact between the template and substrate surfaces by using a flexure stage. As a result, 10 μm coarse alignment accuracy and 20 nm fine alignment accuracy can be achieved. Finally, some results of nanostructures and micro devices such as nanoscale trenches and holes, gratings and microlens array fabricated using the prototype tool are presented, and hot embossing lithography, one typical NIL technology, are depicted by taking nanoscale gratings fabrication as an example.     

体外凝血动态检测传感器装调检测误差控制方法

针对体外凝血检测传感器装调检测误差而引起传感器精度降低的关键问题,建立一种体外凝血动态检测传感器的装调检测误差控制方法。根据体外凝血检测传感器工作原理及结构特点,对于传感器装调及测量中所出现的关键误差进行了分析,通过理论分析推导了存在装调误差情况下传感器核心元件弹性支撑与机械探针装调误差与控制公式,搭建装调误差分析控制装置,建立消除装调误差前后传感器振幅变化关系,采用有限元数值分析法对传感器检测位置与倾角误差进行分析,并计算存在检测误差情况下传感器的振幅变化关系。利用本方法对体外凝血动态检测传感器装调检测误差进行消除试验,结果表明弹性支撑装调误差、探针装调偏转误差、检测对中误差对传感器振幅影响分别为8.263 Pa、9.56 Pa、11.28 Pa,经计算系统总装调检测误差为16.999 Pa,小于体外凝血检测传感器分辨力要求的21.85 Pa,所以本系统的精度可以保证体外凝血检测的精度,验证建立的体外凝血动态检测传感器的装调检测误差控制方法可以满足传感器误差分析的要求,为完善传感器生产工艺、提高产品质量方面提供技术保障,在提升临床凝血快速检测技术中发挥重要的作用。