改善激光共焦扫描显微镜像质的方法

为解决传统光学显微镜样本上每一点的图像都受到邻近点衍射或散射光干扰的问题,研发了一套基于C#WinForm控制平台进行连续扫描方式的激光共焦扫描显微镜(LCSM)系统,并且成功地对生物细胞进行了扫描成像。针对共焦显微镜图像像质不高的问题,提出合理选取探测器针孔直径,并通过高斯低通滤波、盲解卷积的方法,确保实现高像质。实验结果表明,基于上述方法改进后的LCSM具有较高图像质量,该方法简单易行,便于实施。     

基于FPGA的高分辨超声快速扫描成像系统研制

针对超声C扫描成像系统步进式扫描方式速度慢的缺点,研制了一套基于FPGA技术的超声快速扫描成像系统,实现超声换能器在扫描平台连续运动过程中回波信号的快速采集与传输。系统将高精度点聚焦超声显微测试平台和FPGA硬件化信号采集和处理技术相结合,采用FPGA技术进行数位信号的高速采集和处理,利用幅值法和时间法进行回波信号特征值提取,实现了超声快速扫描成像。利用该系统分别对特制试件幅值法和时间法的成像分辨率进行分析;并对硬币和电子封装芯片进行扫描成像测试。结果表明,系统扫描速度快,检测结果直观,成像分辨率高,横纵向分辨力可达50μm,不仅可实现快速清晰成像,而且可进行微小结构的检测,为材料内部缺陷快速检测成像奠定了基础。     

步进扫描光刻机扫描运动轨迹规划及误差控制

研究一种步进扫描投影光刻机工作台扫描运动超精密轨迹规划算法及误差控制策略。在分析三阶扫描运动与步进运动轨迹规划异同点的基础上,提出三阶扫描运动轨迹规划算法。针对扫描运动精确性与严格同步性要求,分析扫描运动轨迹规划误差补偿的几个关键问题。根据扫描运动轨迹算法离散实现存在的误差,结合内部整数积分策略,提出扫描运动轨迹规划加减速段与扫描速度稳定段运动距离的离散积分策略误差控制方法。此外,为克服切换时间圆整引起的扫描曝光匀速段位置误差,提出一种基于常速扫描运动段位置修正因子的误差补偿方法。以上方法共同实现光刻机工作台扫描运动轨迹规划精度控制。实例证明提出算法是有效和精确的。该算法成功应用于100nm步进扫描投影光刻机工作台的超精密运动控制系统中。     

光热三维扫描系统的计算机控制及数据采集

介绍了一套光热三维扫描控制及数据采集系统,它由上位机(PC),分别控制下位机(MCUs)和锁相放大器,实现三个步进电机在三维空间以不同模式带动样品工作台扫描的自动控制,同时能进行采集和保存,并对所采集的数据进行实时成像处理。系统已成功地应用于固体材料的反射式和掠射式光热偏转无损检测。     

扫帚式激光三维扫描成像系统设计与实验

设计了一种基于单线激光雷达的扫帚式三维扫描成像系统来实现目标的三维重建。系统通过激光光束的二维扫描,配合轴向运动,形成包含距离和角度信息的三维点云数据。实测结果表明:采用设计的三维扫描成像系统对距离30m的目标进行测量,角度分辨率达到0.06°,行分辨率达到6cm,帧频达到2Hz,实现了快速扫描、高精度目标测量及系统小型化等目标。     

高速扫描激光共聚焦显微内窥镜图像校正

使用往复式逐行扫描的方式可以提高激光共聚焦显微内窥镜的成像速度和数据利用率,但这种扫描方式也会带来图像畸变和错位问题,从而影响系统成像质量。受扫描畸变影响,图像错位程度不一致,后期处理难以得到理想的校正效果。本文基于共振振镜的运动规律,推导了均匀空间采样过程中的采样时间函数,通过非等时采样方法校正了振镜速度变化带来的横向畸变。利用互相关法评价图像错位程度,采用遗传算法获得最优的采样开始时刻,实现了图像错位的校正。最终通过调整采样开始时刻和时间间隔在数据采集环节校正了图像畸变和错位。为了验证图像畸变校正和错位校正效果,本文搭建了基于往复式逐行扫描方式的激光共聚焦显微内窥成像系统。实验结果表明,该方法能够有效地校正图像畸变和错位,图像的横向分辨率。与现有方法相比,本文方法将图像的局部分辨率由10 pixel提高到6 pixel。     

激光共焦高速扫描显微成像的高帧速重构算法

针对激光共焦扫描显微镜的往复式逐行扫描成像方式带来的帧图像数据分割难的问题,在分析系统扫描方式、振镜的实际运动方式与理论运动方式差异的基础上,利用相邻两帧图像相似性大的特点,提出了一套完整的高帧速重构算法。该算法通过连续帧特征区域差分的方式实现了一维信号序列的自适应分割,即实现了对一维信号序列进行动态排列及分割成二维阵列图像数据,从而重构出多帧高精度图像。实验表明,该算法的成像误差低于1.6%,适用于成像速度高达300帧/s的激光共焦扫描显微成像。     

基于线扫描方式的激光共焦显微镜的研究

激光共焦扫描显微镜(LCSM)是一种新型光学显微镜,它能够对活体组织的深度结构进行清晰的二维或三维成像.由于传统共焦扫描显微镜采用单点扫描方式,成像速度慢,无法满足活体组织实时成像的要求.介绍一种以线扫描方式代替点扫描方式的激光共焦扫描显微镜.线扫描方式不但简化了扫描机构的设计,而且提高了扫描速度,使活体组织的实时成像成为可能.     

高分辨力光学微扫描显微热成像系统设计与实现

为提高已研制的基于非制冷焦平面探测器的显微热成像系统的空间分辨力,研究提出了一种基于光学平板旋转微扫描器的高分辨力显微热成像系统.分析了光学平板旋转微扫描的工作原理,给出了微扫描器相关的参数设计、加工容差,并与现有的非制冷显微热成像系统实现了一体化设计与加工,确定了光学微扫描显微热成像系统的技术指标.利用该系统实际采集的显微热图像与过采样处理结果表明系统整体设计的有效性,系统空间分辨力得到提高,可应用于高分辨力显微热分析.＃     

数字切片扫描技术浅析

详细阐述了现有4种数字切片扫描技术的原理及特点,并对比了优缺点。其中微物镜阵列扫描方案速度快,但实现复杂,成本高;线扫方案可以实现较快的速度,但对控制要求也较高,也容易出现扫描失败的问题;基于面阵传感器扫描的方案,实现较为简单,灵活性较好,可工作于连续运动和走停两种模式,连续运动模式可以提供与线扫接近的扫描速度,走停模式可以提高扫描成功率并获得更好的图像质量。     

单点式位移平台激光共聚焦扫描荧光显微镜

为了获得细胞图像,利用Visual Studio C#开发了移动位移平台的控制程序,使用位移平台单点扫描的方式设计激光共聚焦扫描显微镜(laser confocal scanning microscope,LCSM)。为了获得高分辨率的位移,位移由精度可以达到1nm的压电陶瓷驱动器驱动。设计了梳状和矩形两种扫描路径,通过程序设计位移补偿的方法弥补了机械运动的偏差。利用算术平均值的数字滤波方法处理数据采集卡采集的数据以减小随机噪声的影响。实验结果证明,利用C#程序控制的单点式平台扫描LCSM具有较好地测量效果。     

面向微纳材料的激光扫描二维成像系统

在对微纳材料光学特性表征中,需要获得分辨率更高的波长和强度的荧光图像。普通的显微镜无法满足测试的要求,因此将普通的成像显微镜、光谱仪以及纳米移动台组成激光扫描显微镜成像系统,并利用LabVIEW开发了一套完整的集二维扫描采集与信号图像处理一体的系统上位机软件。扫描采集过程使用了低通滤波等数字信号处理方法消除光谱仪信号噪声的影响。利用本系统测量硒化镉纳米带、单层二硫化钼得到了荧光强度图像以及荧光峰值波长图像,能分辨出最小波长为0.03 nm的荧光。将采集长度与实际长度进行比较并分析荧光强度差异,取得了较好的效果。     

White-light interferometer with partial correlogram scanning

A method for measurement of a surface microprofile with a nanometer resolution is described. The method is based on partial scanning of correlograms in a Linnik white-light interferometer. Experimental results on measurements of thin film thickness are presented. It is shown that a depth resolution of better than 1 nm can be obtained by correlogram scanning in the range from 1 to 2 periods.     

Ultrafast photon counting applied to resonant scanning STED microscopy

To take full advantage of fast resonant scanning in super‐resolution stimulated emission depletion (STED) microscopy, we have developed an ultrafast photon counting system based on a multigiga sample per second analogue‐to‐digital conversion chip that delivers an unprecedented 450 MHz pixel clock (2.2 ns pixel dwell time in each scan). The system achieves a large field of view (～50 × 50 μm) with fast scanning that reduces photobleaching, and advances the time‐gated continuous wave STED technology to the usage of resonant scanning with hardware‐based time‐gating. The assembled system provides superb signal‐to‐noise ratio and highly linear quantification of light that result in superior image quality. Also, the system design allows great flexibility in processing photon signals to further improve the dynamic range. In conclusion, we have constructed a frontier photon counting image acquisition system with ultrafast readout rate, excellent counting linearity, and with the capacity of realizing resonant‐scanning continuous wave STED microscopy with online time‐gated detection.     

Grating interferometer based scanning setup for hard X-ray phase contrast imaging

In x-ray radiography, particularly for technical and industrial applications, a scanning setup is very often favorable when compared to a direct two-dimensional image acquisition. Here, we report on an efficient scanning method for grating based x-ray phase contrast imaging with tube based sources. It uses multiple line detectors for staggered acquisition of the individual phase-stepping images. We find that the total exposure time does not exceed the time needed in an equivalent scanning setup for absorption radiography. Therefore, we conclude that it should be possible to implement the method into a scanning system without affecting the scanning speed or significant increase in cost but with the advantage of providing both the phase contrast and the absorption information at once.     

Reduction in acquisition time of scanning electron microscopy image using complex hysteresis smoothing

Complex hysteresis smoothing (CHS), which was developed for noise removal of scanning electron microscopy (SEM) images some years ago, is utilized in acquisition of an SEM image. When using CHS together, recording time can be reduced without problems by about one-third under the condition of SEM signal with a comparatively high signal-to-noise ratio (SNR). We do not recognize artificiality in a CHS-filtered image, because it has some advantages, that is, no degradation of resolution, only one easily chosen processing parameter (this parameter can be fixed and used in this study), and no processing artifacts. This originates in the fact that its criterion for distinguishing noise depends simply on the amplitude of the SEM signal. The automation of reduction in acquisition time is not difficult, because CHS successfully works for almost all varieties of SEM images with a fairly high SNR.     

Correction of image drift and distortion in a scanning electron microscopy

Continuous research on small‐scale mechanical structures and systems has attracted strong demand for ultrafine deformation and strain measurements. Conventional optical microscope cannot meet such requirements owing to its lower spatial resolution. Therefore, high‐resolution scanning electron microscope has become the preferred system for high spatial resolution imaging and measurements. However, scanning electron microscope usually is contaminated by distortion and drift aberrations which cause serious errors to precise imaging and measurements of tiny structures. This paper develops a new method to correct drift and distortion aberrations of scanning electron microscope images, and evaluates the effect of correction by comparing corrected images with scanning electron microscope image of a standard sample. The drift correction is based on the interpolation scheme, where a series of images are captured at one location of the sample and perform image correlation between the first image and the consequent images to interpolate the drift–time relationship of scanning electron microscope images. The distortion correction employs the axial symmetry model of charged particle imaging theory to two images sharing with the same location of one object under different imaging fields of view. The difference apart from rigid displacement between the mentioned two images will give distortion parameters. Three‐order precision is considered in the model and experiment shows that one pixel maximum correction is obtained for the employed high‐resolution electron microscopic system.     

Fluorescence lifetime imaging in scanning microscopes: acquisition speed, photon economy and lifetime resolution

In this paper a detailed discussion is presented of the factors that affect the fluorescence lifetime imaging performance of a scanning microscope equipped with a single photon counting based, two‐ to eight‐channel, time‐gated detection system. In particular we discuss the sensitivity, lifetime resolution, acquisition speed, and the shortest lifetimes that can be measured. Detection systems equipped with four to eight time‐gates are significantly more sensitive than the two time‐gate system. Only minor sensitivity differences were found between systems with four or more time‐gates. Experiments confirm that the lifetime resolution is dominated by photon statistics. The time response of the detector determines the shortest lifetimes that can be resolved; about 25 ps for fast MCP‐PMTs and 300–400 ps for other detectors. The maximum count rate of fast MCP‐PMTs, however, is 10–100 times lower than that of fast PMTs. Therefore, the acquisition speed with MCP‐PMT based systems is limited. With a fast PMT operated close to its maximum count rate we were able to record a fluorescence lifetime image of a beating myocyte in less than one second.     

扫描电化学池显微镜阿基米德螺旋快速扫描方法的研究

针对现有扫描电化学池显微镜(scanning electrochemical cell microscopy, SECCM)的扫描方法在扫描成像快速性上的不足,提出一种基于阿基米德螺旋线的新型SECCM快速扫描方法。传统跳跃扫描模式的跳跃高度是在没有先验知识的情况下靠人工经验设定的,为了避免碰撞其取值往往偏大,因此设置的扫描行程越长,消耗时间越久,速度慢、效率低。利用螺旋线轨迹预扫描快速获得待测平面的最高点,进而有效地降低了传统跳跃模式的跳跃行程,大幅提高了SECCM的扫描成像速度。此外,以螺旋线轨迹高速运动来检测最高点时,轨迹具有无冲击、因此样本运动过程无偏移,该扫描方法具有成像稳定性高的优点。通过带状金属表面成像实验表明,相对于传统跳跃扫描模式,阿基米德螺旋扫描方法在保证成像质量的同时扫描速度提高了约110%。可见提出的方法对提升SECCM扫描速度和成像质量有着重要的意义。