基于滤光轮双相机系统的高光谱分辨率成像

滤光轮光谱成像系统在光谱成像领域应用广泛,空间分辨率高,但是光谱分辨率较低。针对这一问题,提出了基于滤光轮双相机系统的高光谱分辨率成像,设计了一种基于插分补偿的多光谱计算重构方法,实现系统的高光谱分辨率、高空间分辨率成像。首先利用滤光轮双相机成像系统采集多光谱图像以及RGB图像,然后从多光谱图像获取离散的光谱响应曲线,最后根据RGB三通道数据与光谱高维数据之间的映射关系以及能量守恒定理,进行光谱响应曲线的插分补偿并实现高光谱分辨率成像。实验结果表明,本文方法能够在保持空间分辨率的情况下,高效地实现光谱分辨率为5 nm甚至更高光谱分辨率的成像,重建结果与真实值的均方根误差为0.017 1,具有较好的准确性和鲁棒性。     

Investigation of a high spatial resolution method based on polar coordinate maximum entropy method for analyzing electron density fluctuation data measured by laser phase contrast

Laser phase contrast is a powerful diagnostic method to determine the spatial distribution of electron density fluctuations in magnetically confined plasmas, although its applicability depends on magnetic field configurations. The spatial resolution of fluctuations is linked with the resolution of the propagation direction that is derived from the two-dimensional spectral analysis of the wavenumber for the fluctuations. The method was applied to fluctuation measurements in a compact helical system. In order to improve the resolution of the propagation direction with a relatively small number of data points, the maximum entropy method with polar coordinates was employed. A spatial resolution of the order of 1 cm was obtained, which is satisfactory in a plasma with a 20 cm minor radius.     

Automatic segmentation of fluorescence lifetime microscopy images of cells using multiresolution community detection—a first study

Inspired by a multiresolution community detection based network segmentation method, we suggest an automatic method for segmenting fluorescence lifetime (FLT) imaging microscopy (FLIM) images of cells in a first pilot investigation on two selected images. The image processing problem is framed as identifying segments with respective average FLTs against the background in FLIM images. The proposed method segments a FLIM image for a given resolution of the network defined using image pixels as the nodes and similarity between the FLTs of the pixels as the edges. In the resulting segmentation, low network resolution leads to larger segments, and high network resolution leads to smaller segments. Furthermore, using the proposed method, the mean‐square error in estimating the FLT segments in a FLIM image was found to consistently decrease with increasing resolution of the corresponding network. The multiresolution community detection method appeared to perform better than a popular spectral clustering‐based method in performing FLIM image segmentation. At high resolution, the spectral segmentation method introduced noisy segments in its output, and it was unable to achieve a consistent decrease in mean‐square error with increasing resolution.     

基于事例推理的冲突消解系统研究

在协同设计过程中 ,由于相互影响、制约的协同小组对设计的考虑角度、评价标准、领域知识不尽相同 ,导致了设计冲突的产生 ,冲突在设计过程中具有正、负面影响 ,因而冲突的消解在协同设计系统中占据着重要的地位。但消解过程复杂 ,目前尚缺乏效果良好的方法。基于事例的推理 (CBR)利用以往处理问题的经验 (事例 )作为现在处理当前问题的参考 ,适用于复杂的工程环境 ,本文提出了基于事例推理的冲突消解系统 ,并对系统中的冲突检测、冲突消解作了详细的说明。     

小波多分辨率造型中基于能量法约束条件的处理

针对小波多分辨率造型中的约束问题,结合能量法实现小波编辑过程中约束的处理.由于B样条曲线曲面的线性约束条件可用与其相关的控制点来表示,而不同分辨率层的控制点又可以通过小波变换的方法进行相互转换,由此可将不同分辨率层的约束条件转换并影射到最高分辨率层.再利用小波多分辨率特性结合能量法对约束条件进行转换.在处理最高分辨率层的信息时,由于小波基和原始B样条基的等价关系,可以选用反映曲线大致走向的底层基函数及其控制顶点作为初值进行迭代计算,此时由于系统的自由度少因而迭代速度就变得很快,利用这种方法可以大大提升计算速度.     

A method for personal expertise-independent evaluation of image resolution in scanning electron microscopy

The two conventional methods currently employed for the evaluation of image resolution in scanning electron microscopy are the gap method and a fast Fourier transform (FFT) method. These can be highly dependent on personal expertise on the distinction between signal information and noise contained in a micrograph. Hence, the present paper proposes an alternative method (referred to as a contrast-to-gradient (CG) method) that can determine the image resolution of a micrograph without requiring personal expertise on the judgment of noise. The image resolution in the CG method is defined as a weighted harmonic mean of the local resolution, which is proportional to the quotient of the threshold contrast divided by the local gradient. The local gradient is calculated from the quadratic function that best fits the local pixel intensities over 5 x 5 pixels. It has been shown that the CG method, compared with the FFT method, has a broader range of applications for various types of images, such as low-contrast, noise-containing, filter-processed, highly directional, and quasi-periodic feature images.     

Entropy‐assisted image segmentation for nano‐ and micro‐sized networks

Image analysis is an important tool for characterizing nano/micro network structures. To understand the connection, organization and proper alignment of network structures, the knowledge of the segments that represent the materials inside the image is very necessary. Image segmentation is generally carried out using statistical methods. In this study, we developed a simple and reliable masking method that improves the performance of the indicator kriging method by using entropy. This method selectively chooses important pixels in an image (optical or electron microscopy image) depending on the degree of information required to assist the thresholding step. Reasonable threshold values can be obtained by selectively choosing important pixels in a complex network image composed of extremely large numbers of thin and narrow objects. Thus, the overall image segmentation can be improved as the number of disconnected objects in the network is minimized. Moreover, we also proposed a new method for analyzing high‐pixel resolution images on a large scale and optimized the time‐consuming steps such as covariance estimation of low‐pixel resolution image, which is rescaled by performing the affine transformation on high‐pixel resolution images. Herein, image segmentation is executed in the original high‐pixel resolution image. This entropy‐based masking method of low‐pixel resolution significantly decreases the analysis time without sacrificing accuracy.     

单光子荧光时间谱仪时间分辨率的设计和测定

探讨了影响时间分辨单元光子荧光谱仪时间分辨率的因素,组装和调试了三种类型的时间相关单光子荧光谱仪,测定了它们的激发光脉冲响应函数,提出了测定时间分辨率的方法,并测定了时间分辨率。     

旋转变压器用高精度编码器的设计

本文介绍了一种提高旋转变压器测角精度的方法,采用硬件补偿型编码器电路,可将数字精度由１３位提高到１５位,并且这种补偿方法具有一定的推广价值。     

基于图像清晰度评价的磨削表面粗糙度检测方法

针对当前机器视觉检测粗糙度主要采用图像灰度值信息进行统计分析,没有充分利用色彩信息且忽略了人眼视觉系统主观评判的问题,提出一种基于图像清晰度评价的磨削表面粗糙度检测方法。根据色块在不同等级粗糙度表面上形成的图像清晰度不一样,采用熵函数评价算法和基于色彩相关性的彩色图像清晰度评价算法分别构建清晰度与粗糙度之间的关系模型,论证了基于图像清晰度检测磨削表面粗糙度方法的可行性。试验结果表明,基于图像清晰度检测磨削表面粗糙度是一种可行的粗糙度检测方法,清晰度与粗糙度相关性强,清晰度有随着粗糙度的增大而减小的趋势,且利用色彩相关性的彩色图像清晰度评价算法对磨削表面粗糙度检测具有较好的灵敏性,并且该方法符合人眼视觉系统的主观评价;清晰度算法和主观评价二者结合可快速简易地在线检测工件的整体表面轮廓粗糙度。     

Subnanometric calibration of a differential interferometer

A novel self-calibration method is proposed for calibrating differential interferometers with subnanometer resolution, and the basic characteristics of the method are discussed. Analysis shows that without using any external reference, the calibration accuracy approaches the resolution limit of the interferometer, which is determined by the signal-to-noise ratio (SNR) and the stability of the measurement system. A compact differential interferometer that uses a laser diode as the light source has been developed in order to demonstrate the viability of the proposed calibration method. The conventional fringe-counting and phase modulation methods are combined in order to extend the measurement range and improve the resolution of the interferometer. The developed interferometer was calibrated using the new method, and the calibration results were compared to those obtained by a comparison calibration method that uses a capacitance displacement sensor as the reference.     

A Large and Thin Scintillation Plate as a Charged-Particle Coordinate Detector

A new method of light collection in a scintillation plate with wavelength-shifting fibers is described. Using this method, it is possible to determine the coordinates of charged particles traversing the plate. The spatial resolution of the system is comparable to the scintillation-plate thickness and competitive in comparison with the resolution of wire chambers. The results of the experimental testing are presented.     

振动数据处理中分辨率的确定方法及应用

在振动数据的处理过程中,需要对振动数据进行频谱分析,分辨率选择的好坏将直接影响到分析结果。分辨率的选择并非越高越好,应根据试验结果进行选择。选择与试验结果匹配的分辨率非常重要,如果数据处理分辨率选择不当,处理结果有可能误差比较大甚至错误,此外当分辨率无法改变时还可以根据分辨率选择数据段,以保证处理结果的准确性。本文根据工程实验总结出了振动数据频谱分析过程中分辨率的选择以及试验数据段选取的方法,在处理振动数据中验证了其正确性。     

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.     

基于亚像元CCD几何超分辨方法研究

摘要:为了在现有CCD像元尺寸的基础上提高CCD像元分辨力,对CCD几何超分辨问题进行了研究。从研究现状入手,给出了现有算法及其存在的不足,建立了亚像元超分辨成像数学模型,提出了基于亚像元的CCD几何超分辨方法：两片线阵CCD集成在同一器件中,在线阵方向上错开半个像元,同时读出时间减半,最终交织重组图像数据,以合成高分辨率图像。利用MATLAB7.0.1软件对双线性插值方法及亚像元成像方法进行了仿真,并定性定量地比较两种方法的效果。结果显示：亚像元方法合成图像分辨率约为低分辨率图像的2倍,且PSNR比双线性插值图像高0.2dB。该方法可以实时合成高分辨率图像,显著地减轻欠采样引起的图像模糊。     

A method for estimating spatial resolution of real image in the Fourier domain

Spatial resolution is a fundamental parameter in structural sciences. In crystallography, the resolution is determined from the detection limit of high‐angle diffraction in reciprocal space. In electron microscopy, correlation in the Fourier domain is used for estimating the resolution. In this paper, we report a method for estimating the spatial resolution of real images from a logarithmic intensity plot in the Fourier domain. The logarithmic intensity plots of test images indicated that the full width at half maximum of a Gaussian point spread function can be estimated from the images. The spatial resolution of imaging X‐ray microtomography using Fresnel zone‐plate optics was also estimated with this method. A cross section of a test object visualized with the imaging microtomography indicated that square‐wave patterns up to 120‐nm pitch were resolved. The logarithmic intensity plot was calculated from a tomographic cross section of brain tissue. The full width at half maximum of the point spread function estimated from the plot coincided with the resolution determined from the test object. These results indicated that the logarithmic intensity plot in the Fourier domain provides an alternative measure of the spatial resolution without explicitly defining a noise criterion.     

基于连续扫描方式的激光共焦扫描显微镜的研制

研发了一套基于连续扫描的激光共焦扫描显微镜(laser confocal scanning microscopy,LCSM)系统。该系统采用工作台连续运动方式实现扫描,提出了利用单次采集的数据滤除随机噪声的方法,避免了多帧取平均对成像速度造成的影响。实现连续扫描的关键在于解决工作台运动与数据采集的同步问题,利用采集卡有限采集模式,合理匹配工作台参数和采集参数,成功解决了这一问题。详细介绍了影响分辨率的因素,通过合理选取探测器针孔直径,取样间隔,确保了实现高分辨率的要求。系统利用Visual C#开发的控制平台,成功地对生物细胞进行了扫描成像。实验结果表明:基于连续扫描的LCSM具有较高的分辨率,生成的显微图像没有任何畸变,并且成像速度有了大幅度提高。     

Simultaneous Fusion and Denoising of Panchromatic and Multispectral Satellite Images

To identify objects in satellite images, multispectral (MS) images with high spectral resolution and low spatial resolution, and panchromatic (Pan) images with high spatial resolution and low spectral resolution need to be fused. Several fusion methods such as the intensity–hue–saturation (IHS), the discrete wavelet transform, the discrete wavelet frame transform (DWFT), and the principal component analysis have been proposed in recent years to obtain images with both high spectral and spatial resolutions. In this paper, a hybrid fusion method for satellite images comprising both the IHS transform and the DWFT is proposed. This method tries to achieve the highest possible spectral and spatial resolutions with as small distortion in the fused image as possible. A comparison study between the proposed hybrid method and the traditional methods is presented in this paper. Different MS and Pan images from Landsat-5, Spot, Landsat-7, and IKONOS satellites are used in this comparison. The effect of noise on the proposed hybrid fusion method as well as the traditional fusion methods is studied. Experimental results show the superiority of the proposed hybrid method to the traditional methods. The results show also that a wavelet denoising step is required when fusion is performed at low signal-to-noise ratios.     

凹面光栅分辨率的检测方法研究

构建满足凹面光栅使用条件的精确检测系统来检测凹面光栅的分辨率,根据系统的光源带宽、狭缝宽度和探测器像素尺寸的理论分析,结合凹面光栅的像差分析,给出一种凹面光栅分辨率检测系统的检测方法。系统按照JB/T 8239.2—95《衍射光栅技术条件》的标准方法,定量分析出上述三个因素的影响量,并提出了合理的计算方法,从而在检测系统的测量值中得到了凹面光栅实际的分辨率值。通过实验验证,实际检测结果与理论分析结果相差0.001 0~0.003 7nm,是一种能够真实反映凹面光栅分辨率的光学检测方法。     

Axial tomographic confocal fluorescence microscopy

By physical rotation of the sample, axial tomography enables the acquisition of otherwise inaccessible spatial information from an object. In combination with confocal microscopy, the method can fundamentally improve the effective three‐dimensional (3D) resolution. In this report we present a novel method for high resolution reconstruction of confocal axial tomographic data. The method automatically determines the relative angles of rotation, aligns the data from different rotational views and reconstructs a single high resolution 3D dataset. The reconstruction makes use of a known point spread function and is based on an unconstrained maximum likelihood deconvolution performed simultaneously from multiple (in our case three) angular views. It was applied to simulated as well as to experimental confocal datasets. The gain in resolution was quantified and the effect of choice of overrelaxation factors on the speed of convergence was investigated. A clearly improved 3D resolution was obtained by axial tomography together with reconstruction as compared with reconstruction of confocal data from only a single angular view.