Optimization the parameters of multichannel continuously scanning digital X-ray radiography systems

Analytical formulas for optimal selection of the values of the main parameters of a multichannel continuously scanning digital X-ray radiography system, which is based on a linear detector array, and the minimum required value of the exposure dose rate from an X-ray source are obtained using the specified values of the system’s spatial resolution in the “worst case” and the testing capacity taking the digital filtering of the radiation detection results into account.     

Optimal selection of parameters of multichannel continuously scanning digital-radiography systems

For continuously scanning digital-radiography systems containing a linear detector array, a problem of optimal selection of the length and width of the aperture of an individual detector in this array, the radiation detection time, and the impulse response of a digital filter was solved. The maximum of the system’s spatial resolution in the “worst case” served as the optimality criterion for a specified testing capacity.     

A mathematical model of multichannel continuously scanning systems for digital X-ray analysis

A mathematical model of continuously scanning systems for digital X-ray analysis is developed. The systems contain a linear array of detectors that can be used not only in systems of radiation sources with an anisotropic angular distribution and a nonuniform distribution of the quantum yield over the focal spot but also in systems of detectors with nonuniform spatial sensitivity to incident radiation. The systems also make it possible to normalize the records of the radiation image of a tested object and perform digital filtering of the results.     

Selecting parameters of discrete scanning systems for digital X-ray imaging

For discrete scanning systems of digital X-ray imaging that contain an array of detectors, optimum values of the aperture length for each detector in the array and the step of discrete displacement (scanning) of a tested object are found. The determined values ensure the maximum resolution of such systems in the scanning direction for a given testing performance.     

多通道数字化快门速度测试仪的设计与实现

多通道数字化快门速度测试仪主要应用于幕帘式相机快门有效曝光时间的测试。在像面上的不同点设置多组光电接收器,将像面接收到的光信号转换为电信号。高速数据采集系统利用DMA方式按时序对各接收器的曝光信号进行实时瞬态数据采集。采集数据经计算软件处理,得到各点处的快门有效曝光时间。利用软件解决了瞬态信号与实时采集同步的问题。测试系统简单可靠、测试结果显示直观。     

光谱分析用多通道检测器的工作原理和选用

介绍了用于光谱测量的三种多通道检测器（电荷注入器件、电荷耦合器件、MOS图像传感器）的原理，对主要型号多通道检测器的特性进行了分析与比较，讨论了在设计光谱仪器时选用多通道检测器的原则。     

探地雷达在盾构前向探测应用中工作参数的选择

为了实现利用探地雷达对盾构前向地质做出超前预报,规避盾构施工风险,选取适当的探地雷达中心频率及地质数据采集参数,对提高数据的可靠性和有效性极为重要.结合盾构施工要求,分析了探地雷达天线中心频率选择的主要影响因素,指出天线中心频率的选择既要满足对探测深度和分辨率的要求,又要满足其在盾构机上的安装情况.总结了探地雷达在盾构前向探测超前预报应用中地质数据采集参数设置的一些基本原则与技巧,分析了A/D采样位数、采集点数和扫描速率三者之间的关系.     

Development of X-ray excitable luminescent probes for scanning X-ray microscopy.

Transmission soft X-ray microscopy is now capable of achieving resolutions that are typically 5 times better than the best-visible light microscopes. With expected improvements in zone plate optics, an additional factor of two may be realized within the next few years. Despite the high resolution now available with X-ray microscopes and the high X-ray contrast provided by biological molecules in the soft X-ray region (lambda = 2-5 nm), molecular probes for localizing specific biological targets have been lacking. To circumvent this problem, X-ray excitable molecular probes are needed that can target unique biological features. In this paper we report our initial results on the development of lanthanide-based fluorescent probes for biological labeling. Using scanning luminescence X-ray microscopy (SLXM, Jacobsen et al., J. Microscopy 172 (1993) 121-129), we show that lanthanide organo-polychelate complexes are sufficiently bright and radiation resistant to be the basis of a new class of X-ray excitable molecular probes capable of providing at least a fivefold improvement in resolution over visible light microscopy. Lanthanide probes, able to bind 80-100 metal ions per molecule, were found to give strong luminescent signals with X-ray doses exceeding 10(8) Gy, and were used to label actin stress fibers and in vitro preparations of polymerized tubulin.     

数字电影滤光反射镜光谱设计

为了满足数字电影光学系统色温要求及提高光源能量利用效率,降低设计及光学薄膜镀制难度,计算了色温变化小、光源利用效率高的可见光高反射光谱波段。根据椭球滤光反射镜的工作原理及滤光薄膜的光谱特性,结合氙灯光源光谱及人眼的视觉函数,分析了可见光不同光谱波段对系统光效率及色度坐标的影响。获得了可见光波段光效利用率高,色度参数变化小的波段范围,解决了数字电影反光镜滤光薄膜可见光高反射波段初始设计问题。由滤光薄膜设计及镀制结果得到,405～690nm波长范围可作为数字电影滤光反射镜薄膜高反射区域,相比与氙灯光源光谱,x、y色度偏差不超过0.001,理论反射光光效率达99%以上。     

CR扫描仪激光扫描光学系统的设计

设计了一种适合于计算机X射线扫描仪的新型激光扫描系统,其空间分辨率为10lp/mm。针对常用扫描机构的不足,用五角棱镜和聚焦物镜组成扫描臂取代传统的Fθ镜头,利用成像板的柔韧性实现圆弧形进片,扫描臂同时作为接收器收集激发出的荧光,从而简化系统结构,提高系统性能。利用所设计的光学系统,分析了激光光点大小对分辨率的影响,结果显示光点越小,系统分辨率越高。分析了系统中影响激光光点大小的因素,在高转速条件下对扫描臂进行了有限元仿真,计算了当入射光与五角棱镜入射面不垂直及五角棱镜存在安置误差时,对激光光点大小的影响。结果显示光点直径最大相对变化量为0.07%,表明所设计的激光扫描光学系统具有一定的容差性和实用性。通过实验验证了所研制扫描仪的性能,结果表明图像具有良好的视觉效果,能够满足工业检测要求。     

一种称重系统的数字滤波算法及编程实现

本文介绍一种较为实用的称重系统用数字滤波算法,并给出其C语言的实现程序,希望与从事称重系统研发的工程技术人员共同探讨,共同进步,一起推动称重行业的发展。     

瞄准误差对多通道X射线KB显微镜一致性的影响

围绕着八通道Kirkpatrick-Baez(KB)显微镜在神光-Ⅲ主机上的应用,分析了瞄准误差对该显微镜成像性能和通道间一致性的影响。通过光线追迹,模拟了X射线显微镜的空间分辨率、像点间隔和系统效率随视场和物像距的变化。从中心视场到±200μm视场,空间分辨率下降约2.9μm;从中心视场到±150μm视场,系统效率降低了约60%;物距变化量在±200μm范围时,像点间隔变化值约为0.67 mm,显微镜系统效率变化约为7%;像距变化量在±20mm范围时,像点间隔变化值约为0.70 mm。结果表明,视场中心瞄准误差严重影响空间分辨率和效率,但对各通道间的像间隔影响较小。物距和像距误差对像间隔影响较大,但对空间分辨率和系统效率影响较小。     

X光机数字化的研究进展

数字化X光机相对于传统屏片式X光机具有的高灵敏度,低噪声,数字化图片等优点。详细介绍两种X光机数字化方法:计算机X射线摄影(CR)和数字X射线摄影系统(DR)的组成部分、工作原理和最新进展。最后给出了各种X光机量子探测率和MTF随空间分辨力变化曲线,说明基于直接型平板探测器的DR系统具有更优越的性能,是数字化X光机的最终发展方向。     

State-of-the art and development prospects of digital radiography systems for nondestructive testing,evaluation, and inspection of objects: a review

A review of modern state and practical applications of various digital radiography systems that are intended for nondestructive testing, evaluation, and inspection of objects is presented. The mainstream trends of development are described.     

飞点扫描X射线背散射系统研究

围绕车辆贩运违禁品的精确、快速查缉需求,开展了小型化、低辐射的飞点扫描X射线背散射系统研究。设计了小型化飞点扫描X射线背散射系统的斩波机构、背散射探测器。利用研制的系统开展了X射线背散射成像实验,研究了X射线能量、功率对系统成像对比度和信噪比的影响。实验表明,系统成像分辨率约为2 mm,能够准确检测出隐藏在陶瓷物品中的毒品模拟物。小型化飞点扫描X射线背散射系统的研究可为车辆安检难题和降低检测中的辐射危害提供参考。     

Investigation of laser-welded titanium and stainless steel specimens using digital radiography methods

Specimens of ??titanium-titanium?? and ??titanium-12X18H10T steel?? welded joints that were obtained using laser radiation were investigated. When ??titanium-12X18H10T steel?? welded joints were formed, a copper plate was used as the intermediate insert. The digital computer radiography method using phosphorous image plates was used to study specimens; images were read out from image plates using an HD-CR 35 laser reader produced by Durr NDT. Fuji SR and Kodak SO-170 image plates were used in the experiments. The relative contrast sensitivity of X-ray images of specimens that was obtained experimentally was 1?C1.5% at exposures that were two to three times lower than for conventional radiography on an X-ray film. Defects with openings of > 0.1 mm were detected.     

Intensity correction of fluorescent confocal laser scanning microscope images by mean-weight filtering

This paper addresses the problem of intensity correction of fluorescent confocal laser scanning microscope images. Confocal laser scanning microscope images are frequently used in medicine for obtaining 3D information about specimen structures by imaging a set of 2D cross sections and performing 3D volume reconstruction afterwards. However, 2D images acquired from fluorescent confocal laser scanning microscope images demonstrate significant intensity heterogeneity, for example, due to photo‐bleaching and fluorescent attenuation in depth. We developed an intensity heterogeneity correction technique that (a) adjusts the intensity heterogeneity of 2D images, (b) preserves fine structural details and (c) enhances image contrast, by performing spatially adaptive mean‐weight filtering. Our solution is obtained by formulating an optimization problem, followed by filter design and automated selection of filtering parameters. The proposed filtering method is experimentally compared with several existing techniques by using four quality metrics: contrast, intensity heterogeneity (entropy) in a low frequency domain, intensity distortion in a high frequency domain and saturation. Based on our experiments and the four quality metrics, the developed mean‐weight filtering outperforms other intensity correction methods by at least a factor of 1.5 when applied to fluorescent confocal laser scanning microscope images.     

可编程器件在纳秒级多通道数字延迟/脉冲发生器中的应用

研制了用于飞行时间质谱仪（TOF）的多通道数字延迟/脉冲发生器系统。介绍了复杂可编程器件（CPLD）和可编程数字延迟线（AD9501）在系统中的应用，讨论了高速数字系统中的定时误差问题。该系统的延迟分辨率达1ns，脉冲宽度分辨率为100ns，可同时控制五台设备工作。     

埋弧焊X射线焊缝图像缺陷分割检测技术

针对在埋弧焊X射线焊缝图像的强噪声和弱对比度特点下常规图像分割算法成功率低的现状,通过综合的分析和实验有针对性地给出了系统、实用的缺陷分割方法.首先通过实验给出了一种提取焊缝图像感兴趣区域(the region of interest,ROI)的方法.该方法通过中值滤波,基于sin函数的图像增强、大津法分割、Sobel算子边缘检测和Hough变换可以定量计算出X射线焊缝图像的ROI区域.进一步通过实验给出基于大津法的焊缝缺陷分割算法,实验表明在无人工设定初始分割阈值情况下这一分割算法具有较高的分割成功率.为进一步提高分割成功率,针对焊缝缺陷相对面积较小的特点,提出将缺陷视为噪声,将平均局部平均灰度视为密度,利用密度聚类方法进行缺陷分割.该方法在78张有缺陷的焊缝图像中,成功地分割出74张图像中的缺陷.最后在所研究算法基础上给出了一个综合考虑到各种因素的分割算法,即可节约计算时间,又可以保证分割的成功率.