共查询到20条相似文献,搜索用时 203 毫秒
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抛物面型X射线组合折射透镜光学性能分析 总被引:1,自引:0,他引:1
抛物面型X射线组合折射透镜是一种适用于硬X射线波段的新型光学元件.由于采用抛物面型,可以消除球差,因而能够产生亚微米尺度焦斑并具有更好的成像性能.本文给出了旋转轴对称抛物面型X射线组合透镜的理论研究成果.首先,利用矩阵光学方法,推导了其精确的焦距公式,得到了薄透镜判定准则;其次,根据衍射理论,推导出焦点处的光强分布,得到其极限焦斑大小.最后,本文还给出了透过率和有效孔径的理论公式.针对用Al、Be、PMMA三种材料制作的抛物面型X射线组合折射透镜,本文给出了各个光学性能指标的数值计算沣结果. 相似文献
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X射线探测在医学影像、安检、工业无损探测等领域应用广泛。卤化物钙钛矿X射线探测器因具有灵敏度高、检测下限低等显著优点而引人瞩目,然而三维结构的钙钛矿内部离子迁移显著,导致其稳定性较差。研究表明,低维结构可以有效抑制钙钛矿中的离子迁移,进而提高钙钛矿X射线探测器的稳定性。本文围绕X射线探测器的工作原理、关键性能参数、低维钙钛矿材料及器件等方面,详细介绍了低维钙钛矿X射线探测器近期的研究进展,系统分析了低维钙钛矿材料的结构特性及其对X射线探测性能的影响。低维钙钛矿可实现兼具高灵敏度和高稳定性X射线探测器的制备,是发展潜力巨大的候选材料。进一步优化材料体系,设计器件结构,制备大面积、像素化的成像器件,深入研究探测器的工作机制等是促进低维钙钛矿X射线探测器走向应用的关键。 相似文献
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薄膜X射线应力分析的实验方法 总被引:1,自引:0,他引:1
刘毓舒 《理化检验(物理分册)》2005,41(9):447-450
提出一种适用于薄膜材料X射线应力分析的试样三维定向模式,在X射线低掠入射的前提下允许按实验所需选择测量方向.高密勒指数晶面衍射和测量方向的合理选择有助于提高测量精度,也利于经典sin2ψ分析法实验线性关系的建立,从而简化了分析和计算程序. 相似文献
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刘毓舒 《理化检验(物理分册)》1997,33(11):14-16
多相材料中各相形状和尺寸的空间分布可能引起X射线的各向异性吸收,导致其衍射强度取决于试样相对实验坐标体系的三维取向,这种衍射强度的空间三维分布不仅可以提供衍射相的晶体学取向分布,而且能反映各组成的相形状,尺寸几何分布的信息。介绍一种利用普通织构测角器测定三维极图的方法。 相似文献
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小角X射线散射(SAXS)是一种有效的材料亚微观结构表征手段。简单介绍了小角X射线散射理论,并综述了小角X射线散射技术在材料研究中的应用,内容涉及纳米颗粒尺寸测量,合金中的空位浓度、合金中的析出相尺寸以及非晶合金中的晶化析出相的尺寸测量,高分子材料中胶粒的形状、粒度以及粒度分布测量,以及高分子长周期体系中片晶的取向、厚度、结晶百分数和非晶层厚度的测量等等。 相似文献
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陶瓷/金属封接过程中容易产生残余应力,将影响到封接强度和产品的可靠性。应用薄壳理论和ANSYS有限元分析软件对典型结构的应力分布进行了计算,同时应用X射线衍射法对该结构的应力进行了测试。结果表明,计算值和测量值的趋势基本一致,都是在陶瓷侧的外表面靠近界面的地方存在着最大的轴向拉应力。 相似文献
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针对X射线波长短、能量高,不易直接将X射线波长溯源至SI国际单位,通过采用不同单色器单色化入射X射线,将入射光源溯源至单晶硅晶格参数.结果显示X射线波长引入的最大不确定度为0.0013nm. 相似文献
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Hein I.A. 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1995,42(5):854-869
This paper reports on estimating the 3-D flow velocity vector of blood with ultrasound triple-beam lens transducers. The design, construction, and characterization of experimental lens transducers is described along with the theory of 3-D flow velocity estimation. A triple beam lens transducer consists of three piezoelectric elements mounted on the top surface of a lens. The lens acts to direct and focus the ultrasound from the elements such that three parallel, closely spaced ultrasound beams are generated. Blood cell scatterers are tracked as they move along the beams and from beam to beam using RF correlation techniques. Lenses from fused quartz and aluminum have been designed and fabricated, and the characteristics of the lenses along with lens design considerations and tradeoffs are discussed. The three-dimensional flow velocity vector of fluid in a blood flow phantom has been experimentally measured with an aluminum lens, indicating that the accurate estimation of the 3-D blood flow velocity vector is possible 相似文献
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Xiangxia SongXiaobo Zhang Gang LiuXianchao Cheng Wenjie LiYong Guan Ying LiuYing Xiong Yangchao Tian 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2011,659(1):531-536
The introduction of precision optical elements to X-ray microscopes necessitates fine realignment to achieve optimal high-resolution imaging. In this paper, we demonstrate a numerical method for simulating image formation that facilitates alignment of the source, condenser, objective lens, and CCD camera. This algorithm, based on ray-tracing and Rayleigh-Sommerfeld diffraction theory, is applied to simulate the X-ray microscope beamline U7A of National Synchrotron Radiation Laboratory (NSRL). The simulations and imaging experiments show that the algorithm is useful for guiding experimental adjustments. Our alignment simulation method is an essential tool for the transmission X-ray microscope (TXM) with optical elements and may also be useful for the alignment of optical components in other modes of microscopy. 相似文献
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A new optical system for transmission optical projection tomography (TOPT) is presented to reduce the divergence of the projection data from the true parallel projections. This is performed by introducing an iris at the back focus of the objective lens. The influence of the defocusing on TOPT is demonstrated by computational simulations and experiments. We compare the performances of the new and conventional TOPT systems in order to optimize the optical system for three-dimensional imaging of the embryos of small animals. The optimal imaging performance is given by the new system with numerical apertures between 0.007 and 0.014, with which the spatial resolution of 25 microm is achieved. The optimal configuration is validated by TOPT of a phantom sample and a fixed five-day chick embryo. 相似文献
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Peterzol A Padovani R Quai E Vano E Prieto C Aviles P 《Radiation protection dosimetry》2005,117(1-3):38-43
The image quality (IQ) evaluation of a charge-coupled device (CCD)-based digital angiography system was assessed with respect to modulation transfer function and noise power spectrum. These values were used to calculate the system's frequency-dependent detective quantum efficiency (DQE). The X-ray image detector was an image intensifier (II) lens coupled to a CCD camera. Two measurement setups were used. Setup A is standard IQ assessment, while Setup B more closely represented clinical conditions (polymethyl methacrylate (PMMA) of varying thickness placed between the X-ray tube and II, with test object positioned between PMMA slices 30 cm from the II). Exposure parameters varied according to automatic brightness control settings. Setup B included X-ray radiation scattered by the patient-PMMA. A clinical DQE, describing the transmission of the input signal-to-noise ratio associated with both primary and secondary X-ray spectra, was defined. 相似文献
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球面投影光刻物镜的设计 总被引:2,自引:2,他引:0
针对人工晶体或隐形眼镜的面形上连续浮雕结构加工的特点,本文介绍了基于空间光调制器(DMD)曲面投影光刻物镜系统的设计方法.根据其成像面为曲面的特点,根据光学设计理论多次利用弯向物方的弯月形负透镜结构进行场曲校正,同时运用光的衍射原理优化设计物镜系统的数值孔径以消除DMD投影过程中的栅格效应. 运用ZEMAX工程光学设计软件对系统进行了模拟、优化,并对优化后的结果进行了分析.对于设计实例利用上述设计原则给出了设计结果,工作波长为g线(峰值波长λ=436nm),像面曲率r=22.5mm,视场φ6mm,数值孔径NA=0.1,分辨力为7.8 μm(64Ip/mm)时的光学调制传函值>0.8,畸变<±0.05%. 相似文献
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介绍了毛细管X光透镜的工作原理和物理特性。将微会聚X光透镜应用于四圆衍射仪,对直径为0.6,0.4和0.2mm的化合物晶体做了衍射对比试验。结果表明:在衍射分辨率和调光精度达到原来试验要求的前提下,三种尺寸的晶体衍射强度得到了不同程度的提高,其中直径为0.2mm的化合物晶体的衍射强度增益接近5倍。同时介绍了其在残余应力衍射分析中的应用。 相似文献
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We propose a three-dimensional optical-memory device in which refractive dot data are recorded directly into a photorefractive crystal. To record a single bit of datum, one focuses a laser beam with an objective lens onto a specific spot in a crystal, thereby changing its refractive index locally as a result of photorefraction. To record in three dimensions, one keeps the objective lens stationary while the crystal is translated. The beam-spot intensity is modulated with a beam shutter according to the logic state of the data point. The recorded data points are read with a phase-contrast microscope objective lens. We present experimental results of three-dimensional recording and reading with a LiNbO(3) crystal. The distribution of the refractive index formed by a focused beam is also analyzed with the charge-transport model. 相似文献
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Alessandro Pisa 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2007,580(3):1565-1570
An analytical study of the geometrical properties of the X-ray diffraction applied to the case of Laue lenses is reported in this paper. The results of this investigation are analytical equations that describe the point in which a photon is diffracted as a function of the crystal position and of the X-ray source angular coordinates. In addition, the contributions to the lens Point Spread Function of each crystal is described, helping in understanding the optical properties of a Laue lens. The results obtained can be inserted in simulation and image deconvolution softwares for speeding up the calculations. 相似文献
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平顶多高斯光束通过球差透镜的聚焦特性 总被引:5,自引:1,他引:4
利用广义惠更斯-菲涅耳衍射积分公式,研究了平顶多高斯光束通过球差透镜的聚焦特性。推导出轴上光强分布的表达式,并对轴上光强进行大量的数值计算及分析。研究结果表明,当平顶多高斯光束的阶数N一定时,透镜的球差将在很大程度上影响光束的聚焦特性;当透镜的球差一定时,N值的改变将影响轴上最佳聚焦点的位置;当无球差时,轴上最佳聚焦点并不在几何焦点处,轴上最佳聚焦点位置随着N值增加向几何焦点靠近,例如当阶数N由0增大为1时,则归一化最佳聚焦点由0.91增大到0.98。 相似文献