Experimental and simulation study of undesirable short-period deformation in piezoelectric deformable x-ray mirrors

To construct adaptive x-ray focusing optics whose optical parameters can be varied while performing wavefront correction, ultraprecise piezoelectric deformable mirrors have been developed. We computationally and experimentally investigated undesirable short-period deformation caused by piezoelectric actuators adhered to the substrate during mirror deformation. Based on the results of finite element method analysis, shape measurements, and the observation of x-ray reflection images, a guideline is developed for designing deformable mirrors that do not have short-period deformation errors.     

Reflection of attosecond x-ray free electron laser pulses

In order to utilize hard x-ray free electron lasers (XFEL's) when they are extended to attosecond pulse lengths, it is necessary to choose optical elements with minimal response time. Specular grazing-incidence optics made of low-Z materials are popular candidates for reflectors since they are likely to withstand x-ray damage and provide sufficiently large reflectivities. Using linear-optics reflection theory, we calculated the transient reflectivity of a delta-function electric pulse from a homogenous semi-infinite medium as a function of angle of incidence for s- and p-polarized light. We specifically considered the pulse response of beryllium, diamond, silicon carbide, and silicon, all of which are of relevance to the XFEL's that are currently being built. We found that the media emit energy in a damped oscillatory way, and that the impulse-response times are shorter than 0.3 fs for normal incidence. For grazing incidence, the impulse-response time is substantially shorter, making grazing-incidence mirrors a good choice for deep subfemtosecond reflective optics.     

Talbot-Lau x-ray interferometry for high energy density plasma diagnostic

High resolution density diagnostics are difficult in high energy density laboratory plasmas (HEDLP) experiments due to the scarcity of probes that can penetrate above solid density plasmas. Hard x-rays are one possible probe for such dense plasmas. We study the possibility of applying an x-ray method recently developed for medical imaging, differential phase-contrast with Talbot-Lau interferometers, for the diagnostic of electron density and small-scale hydrodynamic instabilities in HEDLP experiments. The Talbot method uses micro-periodic gratings to measure the refraction and ultra-small angle scatter of x-rays through an object and is attractive for HEDLP diagnostic due to its capability to work with incoherent and polychromatic x-ray sources such as the laser driven backlighters used for HEDLP radiography. Our paper studies the potential of the Talbot method for HEDLP diagnostic, its adaptation to the HEDLP environment, and its extension of high x-ray energy using micro-periodic mirrors. The analysis is illustrated with experimental results obtained using a laboratory Talbot interferometer.     

High-pressure in situ density measurement of low-Z noncrystalline materials with a diamond-anvil cell by an x-ray absorption method

We have developed techniques for high-pressure in situ density measurement of low-Z noncrystalline materials with a diamond-anvil cell (DAC) by an x-ray absorption method. In DAC experiments, accurate determination of the sample thickness is difficult. Moreover, since the sample in a DAC is thin and the interaction between low-Z materials and x rays is small, not the sample but the anvils absorb most of x rays. This makes the measurement quite difficult. We have overcome such difficulties and have successfully measured the density of SiO2 glass, a low-Z noncrystalline material, as a function of pressure up to 35 GPa.     

离子束螺旋扫描方式修正光学镜面方法

研究基于螺旋扫描方式的光学镜面离子束修正方法.根据离子束去除函数的特性,将螺旋扫描加工过程简化成线性过程并建立工艺过程模型,采用基于Bayesian原理的改进Richard-Lucy迭代法求解驻留时间.在分析驻留时间的连续速度实现基础上,给出螺旋路径参数的确定准则.建立螺旋扫描加工方式的工艺流程并进行试验验证研究.试验研究对φ100平面镜和φ200非球面镜修形加工得到了面形方均根误差均优于0.01λ.研究结果表明:极轴加工与普通的全口径加工一样是一种高效率、高确定性的加工方法,能够对镜面进行精确修形,同时可以节约加工成本.     

Manufacturing and testing of X-ray imaging components with high precision

1Introduction X rayimagingtechnologyhasbeenoneof themostimportantresearchcontentssince RoentgendiscoveredX rayin1895.Initially,X raywasusedtostudytheinternalstructureof substancesbycontactradiography.Thespeci menisplacedincontactwithaphotographicfilm duringtheX rayexposure.Theimageofthe specimenisdisplayedafterdeveloping.The methodhasbeenuseduntilnow,anditiswidely appliedinmedicaltreatmentandinnerflawsde tectionofindustrialmaterials.Sincetherefractiveindicesofmaterialsin X rayrangearelowert…     

采用多种群遗传算法的全景成像系统非球面设计

提出了一种基于多种群遗传算法(MPGA)的折反射全景成像系统非球面元件的设计方法.结合广义科丁顿公式及几何光学原理,推导出非球面两镜系统像散表达式.在此基础上,利用MPGA,以像散作为非球面两镜系统像差评价参数,求解出满足消像散及指定透视投影关系的非球面面形方程.给出MPGA求解非球面面形的实现过程,并用遗传算法最小二乘混合优化算法得到了便于实现光线追迹和像差计算的非球面多项式.研制了一个焦距为-1.2 mm,F数为1.5 ,视场为360°×(35～90°)的折反射全景成像系统,给出了实验图像,获得了较好的成像质量.     

大口径传输反射镜的研究进展

针对我国惯性约束聚变装置(ICF)对高性能传输反射镜元件的性能要求,探索了大口径传输反射镜制备涉及的关键技术与工艺。深入开展了K9玻璃坯片研制、光学冷加工、传输反射镜镀膜和激光预处理等方面的研究工作。提出了400mm口径K9反射类坯片精密退火工艺,形成了高精度平面加工技术路线;制备了低缺陷薄膜,并且建立了大口径光学元件预处理装置。最后,综述了大口径高性能传输反射镜研制方面的主要成果。研制的400mm口径传输反射镜在1053nm处以45°入射时,其表面粗糙度优于99.8%,面形PV值小于λ/3(λ=1 053nm),损伤阈值大于30J/cm2(5ns)。基于提出的技术研制的大口径传输反射镜已成功应用于我国神光系列高功率激光装置,有力支撑了我国大型激光装置的稳定运行。     

X射线—极紫外光学中的超精密加工及其应用

短波光学技术的发展对高精密超光滑表面提出了严格要求。在X射线—极紫外光学中,光学元件表面粗糙度均方根值必须达到埃量级。制造这样表面的超精加工包括切割、研磨和抛光等工艺过程。本文介绍一种制造X射线望远镜中非球面镜的复制方法。     

X射线—极紫外光学中的超精密加工及其应用

短波光学技术的发展对高精密超光滑表面提出了严格要求。在X射线—极紫外光学中,光学元件表面粗糙度均方根值必须达到埃量级。制造这样表面的超精加工包括切割、研磨和抛光等工艺过程。本文介绍一种制造X射线望远镜中非球面镜的复制方法。     

High-energy x-ray microbeam with total-reflection mirror optics

Total-reflection mirror optics for high-energy x-ray microfocusing have been developed, and tested in the energy range of 30-100 keV at beamline 20XU of Synchrotron Radiation Facility SPring-8. The optical system consists of a Kirkpatrick-Baez-type [J. Opt. Soc. Am. 38, 766 (1548)] focusing optics with aspherical total-reflection mirrors for the purpose of reducing the spherical aberrations. A focused beam size of 0.35 x 0.4 microm(2) has been achieved at an x-ray energy of 80 keV, and the measured spot size was less than 1 microm in the x-ray energy region below 90 keV.     

Triple-path collector optics for grazing incident x-ray emission spectrometer

A new type of collector optics was developed for grazing incident x-ray emission spectrometer. The collector optics used two cylindrical mirrors to add two extra light paths while keeping the center light path that directly illuminates the grating. The design and properties of the spectrometer using the triple-path collector optics were evaluated using ray-tracing simulations, and validity of this design in terms of throughput and energy resolution was confirmed by the experimentally obtained spectra.     

非共轴掠入射X射线显微镜参数的误差分析

设计了一套由4个反射镜组成的非共轴掠入射X射线显微镜,分析了该系统的像差和成像质量。为了研制出高质量的设备,需要制定合理的加工和装配公差。研究了由于元件和结构参数(反射镜的半径,物距,掠入射角等)的误差而引起的高斯参数和像差的变化。首次用点列图和调制传递函数来定量评价图像质量降低的程度,并在此基础上制定了合理的加工和装配公差。在这些公差的约束下,研制成一套非共轴掠入射X射线显微镜,在激光引爆的惯性约束聚变的诊断实验中,用该系统获得了高质量的图像。     

X-ray beam induced current method at the laboratory x-ray source

The x-ray beam induced current method (XBIC) is realized on the laboratory x-ray source using the polycapillary x-ray optics. It is shown that rather good images of grain boundaries in Si can be obtained by this method. The parameters of x-ray beam are estimated by the simulation of Schottky diode image. A good correlation between the experimental and calculated grain boundary XBIC contrast is obtained. The possibilities of laboratory source based XBIC method are estimated.     

Development of Wolter I x-ray optics by diamond turning and electrochemical replication

Demonstration x-ray optics have been produced by diamond turning and replication techniques that could revolutionize the fabrication of advanced mirror assemblies. The prototype optics were developed as part of the Advanced X-ray Astrophysics Facility—Spectrographic program (AXAF-S). The initial part of the project was aimed at developing and testing the replication technique so that it could potentially be used for the production of the entire mirror array. This assembly will ultimately be comprised of up to 50 nested mirror shells. The mirrors are produced by electroforming a thin shell optic with a conical mandrel. The mandrel is diamond-turned electroless nickel over an aluminum substrate. The initial goal was to produce a surface finish on the replicated mirror shell of less than 10 Å rms (measured with a WYKO 3D at 20X). The electroformed mirror shell is made from pure nickel deposited in a state of minimum stress. A cryogenic separation technique is used to remove the finished mirror from the mandrel. The replication technology for the mirror components has the potential to revolutionize the fabrication of precision components. The extremely high precision required of x-ray optics may lead to advances in manufacturing techniques that could be utilized in the fabrication of other precision components. The key procedures of the fabrication process are presented with the appropriate testing results.     

Five-frame, x-ray camera for charged particle, inertial confinement fusion studies

A prototype framing x-ray camera has been developed for photographic studies of inertial confinement fusion (ICF) targets irradiated by charged particle beams. Electron images from five, independently gated, microchannel plates are transported out of the radiation field by means of a toroidal magnetic field and are permanently recorded on film. The calculated, effective exposure time is 相似文献   

Error analysis of the parameters for non-coaxial grazing X-ray microscope

A non-coaxial grazing X-ray microscope, consisting of four spherical mirrors, is designed for diagnosis of inertial confinement fusion (ICF). The aberrations and imaging quality of the microscope are analyzed. To acquire excellent imaging quality, suitable tolerances for manufacturing and assembling the microscope are necessary. This paper researches the changes of Gauss parameters and aberrations due to component and subsystem parameters (such as the radius of the mirror, angle between mirrors, grazing angle, object distance, etc.). Here, spot diagrams and modulation transfer function (MTF) are first adopted to quantitatively evaluate the imaging quality of the microscope. Suitable manufacturing tolerances of components and assembly tolerances of the system are established on the basis of the discussion and analysis. A set of non-coaxial grazing X-ray microscopes is manufactured based on the tolerances. In site tests of ICF, the images with high resolution are obtained by the microscope. __________ Translated from Optics and Precision Engineering, 2006, 14(1): 34–42 [译自: 光学精密工程]     

A cubic boron nitride gasket for diamond-anvil experiments

To maximize the thickness of the sample chamber in high-pressure experiments, we have conducted tests and have developed techniques relevant to the cubic boron nitride (c-BN) gasket for diamond-anvil cells. The c-BN gasket provides a sample chamber several times thicker than conventional metal gaskets. We have developed methods to prepare the gasket and to fill the chamber with the sample. By using the c-BN gasket, we have successfully measured x-ray diffraction patterns of SiO2 glass, a low-Z noncrystalline sample, up to 100 GPa.     

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.     

Diffractive-refractive optics: X-ray collimator

Diffractive-refractive optics are x-ray focusing monochromators based on the diffraction on profiled crystal surface. Diffraction on longitudinal parabolic groove machined in crystal surface forms a sagittaly focused synchrotron radiation beam. Such kind of monochromator may be realized as a crystal with parabolic hole, where the beam is diffracted on the inner wall of the hole. Two such asymmetrically cut crystals set into antiparallel position, creating a dispersive (+,-,-,+) arrangement, form a sagittaly focusing x-ray monochromator which should be practically aberration-free. The focusing properties of such kind of monochromator are discussed in detail and it is shown for the first time that it can be used not only for focusing but also for creating highly parallel monochromatic beam in the broad region of the Bragg angles. This device with parabolic hole has not been tested experimentally yet.