Development,production, and investigation of PMMA-based X-ray compound refractive lenses

Equipment and technology for producing X-ray refractive lenses from polymethyl methacrylate are described. Each single lens has a spherical profile with a radius of 2.38 mm. A compound lens is composed of 235 single lenses. The focal length of the compound lens for 14-keV X-ray photons is 4.8 m. The lenses developed thereby have been tested on the synchrotron radiation source of the Scientific and Engineering Complex at the Kurchatov Centre of Synchrotron Radiation and Nanotechnologies. The advantages and the drawbacks of the parabolic and spherical lenses are discussed.     

平行式Schmidt型龙虾眼X射线光学系统研究

龙虾眼X射线系统是实现大视场X射线成像的有效手段。现研制了由多组平行玻璃平板构成的Schmidt型X射线龙虾眼光学系统,开展了X射线聚焦和成像的演示实验。基于掠入射反射理论,以210μm厚的超光滑平板玻璃作为光学元件,通过堆叠的方式制作了放大倍数为1的演示系统。用8keV的X射线光源对系统进行了聚焦和实验,直径280μm的光源聚焦半高宽约为320μm,与理论模拟结果基本一致。利用X射线背光照明,得到2mm×2mm大小图样的成像。实验结果表明,该龙虾眼光学系统可以在几毫米视场下达到百微米分辨。     

X-ray microtomography

A microscope system based on the principles of computerized axial tomography is described for determining the distribution of the X-ray absorption coefficient in a slice from a solid object without cutting sections. An application is given to determining the distribution at a resolution of about 15 μm through a shell of about 0·5 mm diameter.     

X-ray microscopy using computerized axial tomography

Computerized axial tomography with MoK_a X-radiation has been used to study a 0.8times0.8 mm column of human femoral bone at a resolution of 15 μm. This non-destructive X-ray microscopic technique allowed ‘sections' to be made with 25 μm separation and the distribution of linear absorption coefficient in each section to be determined.     

大高宽比、高线密度X射线透射光栅的制作

利用电子束光刻、X射线光刻和微电镀技术,成功制作了面积为1 mm × 1 mm,周期为300 nm,金吸收体厚度为1 μm的用于X射线显微成像技术的透射光栅。首先利用电子束光刻和微电镀技术在Si3N4薄膜上制作周期为300 nm,厚度为250 nm的高线密度光栅掩模。然后利用X射线光刻和微电镀技术复制厚度为1 μm,占空比接近1：1,高宽比为7的X射线透射光栅。整个工艺流程充分利用了电子束光刻技术制作高分辨率图形和X射线光刻技术制作大高宽比结构的优点     

X-ray microscopy: experimental results with the Göttingen X-ray microscope at the electron storage ring BESSY in Berlin

An X-ray microscope and X-ray microscopy experiments with biological specimens are described. The experiments have been performed with a resolution of about 0.05 μm using the synchrotron radiation of the electron storage ring BESSY.     

X-ray microradiography in the scanning electron microscope or microanalyser

A technique is described which enables microradiographic examination to be carried out in a scanning electron microscope (SEM) or X-ray microanalyser. Comparison can readily be made between the radiographic image, a conventional scanning electron image or X-ray image. A wide range of materials have been examined in a Cambridge Scientific Instruments Microanalyser Mark 1 and a Stereoscan S1 scanning electron microscope and a resolution of 1 μm has been consistently achieved.     

Scanning X-ray radiography with an improved detection scheme

A scanning X-ray microscope based on scannable electron gun is described. In spite of its extremely simple conception (classical X-ray source and no requirement for X-ray optics), it gave good images in about 10–20 min. To check the imaging properties of this system, an integrated circuit was used as a sample; the resulting images show that the resolution is about 6 to 7 μm. This result is discussed, and possible further developments are pointed out. Improvements to bring the theoretical resolution limit to a few tenths of a micrometer are also suggested.     

基于单次全反射椭球单玻璃管X射线聚焦镜表征光源参数

为了正确表征X射线光源参数,本文利用单次全反射椭球单玻璃管X射线聚焦镜,设计了一种测量X射线光源焦斑尺寸和焦深的方法。该方法利用椭球单玻璃管X射线聚焦镜具有单次全反射成像能力的特点,对多个已知焦斑尺寸的多毛细管X光透镜模拟光源的焦斑成像尺寸和椭球聚焦镜的面形误差进行表征,从而确定光源焦斑尺寸和经过椭球聚焦镜后的焦斑成像尺寸以及椭球聚焦镜的面型误差之间的通用数学关系。然后,通过分析待测光源焦斑经过椭球聚焦镜所成像的尺寸来得到被测量光源的焦斑尺寸。利用该法也同样可以得到光源焦深的大小。为了验证设计方法的可行性,测量了实验室微焦斑X射线光源的焦斑和焦深参数。测试显示:对于焦斑直径约为50μm、焦深约为20mm的光源,文中方法得到的算术平均值标准偏差分别为1.5μm和0.7mm。结果表明:本文设计的光源参数表征方法可以实现对微焦斑源焦斑尺寸和焦深的同时测量,在X射线源的研制和应用领域具有潜在应用。     

应用X射线光刻的微针阵列及掩模板补偿

提出了一种聚甲基丙烯酸甲酯(PMMA)微针的微细加工工艺,该工艺基于PCT技术,结合X射线以及光刻掩模制作三维微结构。通过移动LIGA掩模板曝光来加工微立体PMMA结构,其加工形状取决于X光光刻掩模板吸收体的形状。实验显示,最终的结构形状并非完全与掩模板上吸收体的形状一致。如果不对X光光刻掩模板的吸收体形状进行补偿,即会使被加工的微结构侧面变形,从而影响微针的性能。分析了微针阵列侧面变形的原因,认为这种变形是由于显影时间与曝光量之间的非线性关系导致结构形状与曝光量分布不完全一致造成的。利用PCT方法制作的PMMA微针其长度为100～750μm,直径为30～150μm,针尖的直径最小可达100nm。通过对LIGA掩模板上的吸收体图形进行适当的补偿,使吸收体图形从中空的双直角三角形变为中空的半椭圆图形,增强了带沟道的微注射针阵列的强度。     

X射线聚焦望远镜镜片黏接装配的数值模拟和分析

对采用圆锥嵌套Wolter-I型结构的X射线聚焦望远镜在装配过程中产生的面形偏差进行了模拟和分析。首先,利用ANSYS有限元软件建立二维模型。然后,以实际装配步骤和夹具为加载和边界条件,通过分析不同半径镜片的装配过程,得到了面形偏差与三根压条的载荷关系曲线,由此优选出了不同半径镜片对应的最佳装配载荷。分析显示:除对应的最大面形偏差外,优选出的装配载荷均可控制在0.1μm以内,满足装配精度要求,而且对应装配载荷下玻璃镜片的最大Mises应力也均小于玻璃的强度极限,不会在装配过程中失效。此外,建立了三维分析模型并与二维简化模型分析结果进行了比较。结果显示:计算偏差主要集中在镜片的前、后两端约5mm范围内,最大偏差为2.3μm;镜片中段两种模型的计算偏差小于0.03μm,表明提出的二维简化模型可以用于玻璃镜片装配的快速面形偏差分析和载荷确定。文中对镜片装配过程的分析可为提高装配精度提供理论依据。     

Observation of biological materials by X-ray photoelectron-conversion contact microscopy

Dried biological specimens, such as fossil diatoms, collagen, nerve tissue and spicule of Trepang, were observed by X-ray photoelectron-conversion contact microscopy. A spatial resolution of 0·2 μm was attained. The fossil diatom image shows a clear difference below and above the carbon K-absorption edge (4·46nm).     

A compact Schwarzschild soft X-ray microscope with a laser-produced plasma source

A compact Schwarzschild soft X-ray microscope using a laser-produced plasma soft X-ray source has been developed. The laser-produced plasma source, which is small but of high brilliance, has made it possible to use the soft X-ray microscope in a small laboratory. The microscope is composed of a Schwarzschild objective and a grazing incidence mirror condenser. Image contrast for biological specimens in soft X-ray regions is investigated briefly. It is possible to observe the fine structures of a thin specimen at a wavelength of 15 nm; at this wavelength high-contrast images of biological specimens have been obtained with a single laser shot of pulse width of 8 ns at a resolution of 0·3 μm. The resolution of the system is limited by the detector.     

微束XRF系统中X射线聚焦光学元件研究

高性能X射线聚焦光学元件是实现亚微米分辨率微束X射线荧光分析系统(XRF)的关键器件。给出一种新型的微束XRF系统设计结构,介绍两种典型的X射线聚焦光学元件:X射线聚焦毛细管透镜和X射线组合折射透镜的结构与光学参数。数值计算比较了X射线聚焦毛细管透镜和X射线组合折射透镜的光学聚焦性能。分析结果体现了X射线聚焦组合透镜作为聚焦光学元件在焦斑大小、透过率、强度增益和检测范围等方面的优势。     

X射线衍射光学部件的制备及其光学性能表征

综述了国内外在纳米加工X射线衍射光学透镜方面的研究现状和最新进展。介绍了作者团队过去三年在这方面做的工作。针对衍射透镜关键技术,研发了具有大高宽比形貌的电子束光刻基础工艺;结合金电镀,提出了纳米尺度波带片的制造技术,并将该工艺成功扩展于分辨率板(Siemens star)和集成光栅型会聚透镜的研制。运用蒙特卡罗模拟和显影动力学,探索了电子束光刻技术所能够实现的最大高宽比以及造成这种限制的物理根源;成功研制了50~100nm的波带片透镜(其中,100nm波带片高宽比为16∶1)、50~300nm的分辨率测试板(其中,300nm测试板高宽比为10∶1)和200nm的会聚透镜(高宽比为10∶1)。对所研制的光学部件在同步辐射光源进行了实验表征。结果表明,100nm波带片聚焦斑尺寸为234nm,测试板和会聚透镜的光学特性与国外同样光学部件到达同等水平;会聚透镜辐照的均匀性为99%。最后,总结了近几年我国X射线衍射透镜的发展进度,指出了衍射光学部件光学性能发展的最大瓶颈是分辨率与衍射效率相互制约,提出了提高光学部件衍射效率的具体途径,给出了我国X射线衍射透镜技术的未来发展路线图。     

X射线成像波带片及制作

研究了X射线成像波带片的工作原理和制作工艺。从理论上分析了波带片的空间分辨率与最外环宽度的关系,以及波带片衍射效率与厚度和折射率的关系。利用国家同步辐射实验室发展的加工工艺,即电子束光刻技术和X射线光刻技术结合制作波带片。实验结果表明:波带片最外环宽度为150 nm,高宽比为4,基本满足高分辨X射线成像波带片的高空间分辨率、大高宽比、高精度等要求。     

光谱共焦位移传感器镜头设计研究

光谱共焦位移传感器是一种高精度、非接触式位移传感器。本文讨论了光谱共焦法用于位移测量的基本原理,用Zemax光学设计软件完成了一个镜头组的设计,并给出了光谱共焦位移传感器镜头组的设计方法以及像差分析。该镜头组采用密接透镜结构,工作波段为486.13nm-656.27nm,测量范围约为91μm,轴向响应FWHM优于5μm。通过线性回归分析得出波长与位移间判定系数为0.99523,在测量范围内,位移与波长间的线性关系较好。     

New progress in X-ray microscopy

Interest has recently revived in microscopy at X-ray wavelengths, stimulated in part by work for microelectronic lithography. The use of synchrotron radiation and other intense sources of X-rays, the development of plastic foils in place of photo-emulsions for recording and the fabrication of Fresnel zone lenses for focusing X-ray beams have all played a part. Some progress has already been made in improving the resolution and contrast of this method of microscopy, in the wavelength range 2–4 nm. The limitation imposed by radiation damage in biological specimens still has to be explored.     

高通光率金属网栅屏蔽效率分析的等效折射率模型

基于Ulrich半实验方法、LZ等效电抗模型和Kohin等效膜方法,建立了一种新型的高通光率金属网栅屏蔽效率分析的等效折射率模型。该模型精确地建立了金属网栅的等效折射率与其结构参数和边界材料折射率的关系,便于分析电磁波任意入射方向时的金属网栅屏蔽效率,并可克服Chen倾斜模型在分析高通光率金属网栅屏蔽效率时的失效问题。为验证建立模型的有效性,用紫外光刻法制备了周期320 μm、线宽4.5 μm和周期160 μm、线宽5.5 μm的两种网栅,并用微波网络分析仪测试了12~18 GHz波段的屏蔽效率。实验与分析表明:建立的新模型的原理计算误差＜2 dB,优于Chen模型和LZ模型的8 dB的原理计算误差和Ulrich模型的4 dB的原理计算误差,说明新模型能更精确地分析高通光率金属网栅的屏蔽效率。     

整体多毛细管X光透镜在扩展X射线吸收精细结构分析技术中的应用

为了将整体多毛细管X光透镜应用到扩展X射线吸收精细结构分析技术中,对整体多毛细管X光透镜的功率密度增益、光斑稳定性、高能滤波性质等进行了系统表征。通过实验可知,利用基于整体多毛细管X光透镜的扩展X射线吸收精细结构分析设备可对样品进行微区分析,其空间分辨为25 μm左右;利用整体多毛细管X光透镜会聚激光等离子体发出的X射线进行超快时间分辨扩展X射线吸收精细结构分析时,透镜的功率密度增益约为3 000。实验结果证明,整体多毛细管X光透镜可以改善扩展X射线吸收精细结构分析设备的性能。