软X射线能谱定量测量技术研究

采用每毫米1000线的自支撑透射光栅配上背照射软X射线CCD(charge coupled device)组成了透射光栅谱仪,利用北京同步辐射装置(BSRF)3W1B光束线软X射线实验站上X射线源分别对透射光栅的衍射效率和软X射线CCD的响应灵敏度进行了准确的实验标定,获得了150eV到1500eV能区的绝对衍射效率和响应灵敏度的实验结果;同时在国内外研究工作的基础上,发展了自己的透射光栅衍射效率理论计算模型和X射线CCD响应灵敏度计算模型,开展了相应的理论计算和实验标定结果比对工作,理论和实验符合较好,     

透射光栅的实验标定和衍射效率的理论模拟

透射光栅广泛应用于软X射线能谱测量.为了获得用于惯性约束聚变研究的透射光栅的各级衍射效率及其他参数,在北京同步辐射源上200—1600 eV能量范围内对其进行了标定,获得了透射光栅衍射效率的实验结果.扩展了透射光栅衍射效率的计算方法,提出了7边准梯形截面衍射效率计算模型.分析拟合了实验数据,理论结果与实验结果很好符合.得到了7边准梯形的透射光栅栅线截面结构. 关键词： 透射光栅 衍射效率 实验标定 光栅模型     

高线密度X光透射光栅衍射效率

高线密度X光透射光栅是各种高分辨光栅摄谱仪的核心色散元件,为了获得较高的光谱分辨率,工作在2~5 keV能区的光谱仪需要使用5000 l/mm的X射线透射光栅。为了获得光栅的绝对衍射效率,采用同步辐射光在多个能点对5000 l/mm的X光透射光栅进行衍射效率实验标定,通过光栅相对衍射效率拟合获得了光栅结构参数,与光栅结构测量结果非常接近。然后,采用衍射效率的矩形栅线模型,计算得到了光栅的绝对衍射效率。     

弱谐波情况下透射光栅衍射效率标定方法

同步辐射光源中的高次谐波会使透射光栅衍射效率标定精度变差。为了校正光源中的高次谐波对透射光栅衍射效率标定的影响,提出了一种光源存在弱谐波情况下的透射光栅衍射效率标定方法,通过使用谐波X射线的衍射效率修正基波衍射效率标定中谐波的影响,从而得到更为准确的透射光栅衍射效率。使用该标定方法在北京同步辐射光源上开展了透射光栅相对衍射效率标定工作。实验结果表明:在100~800eV存在高次谐波能段,修正后透射光栅一级与零级的相对衍射效率与理论模拟结果吻合较好,修正后光栅二级与一级的相对衍射效率更接近理论模拟结果,但与理论模拟结果仍有较大偏差,该偏差主要来源光栅较弱的二级衍射。     

高谱分辨X光能谱诊断技术

 采用国内首次研制出的2 000线/mm的自支撑透射光栅配上背照射软X光CCD(charge coupled device)组成了高谱分辨透射光栅谱仪。通过实验标定和理论模型计算相结合得到了高线对透射光栅的绝对衍射效率；同时建立了透射光栅谱仪测谱解谱方法，编制了相应的解谱程序。在“神光”激光装置上利用该谱仪通过激光打靶实验获得了金腔靶注入口发射的X光能谱定量实验结果，实验结果表明，该谱仪测谱范围在高能区达到6 000eV,谱分辨达到0.1nm，能够清晰地分辨金等离子体M带三峰分布X光谱结构。     

错位双光栅色散元件设计及衍射效率研究

设计了一种错位双光栅色散元件,与条纹相机耦合实现了0.1~5keV范围X射线时间分辨谱的测量.该色散元件由2 000lp/mm和5 000lp/mm两块子光栅在空间错位排布而成,低密度光栅测量低能段软X射线(100~1 000eV),高密度光栅测量中能段软X射线(1 000~5 000eV),通过空间错位实现能谱拼接.在同步辐射源上使用单色能点对其进行标定,获得了错位双光栅衍射效率的实验结果.根据光栅的结构特性,结合标定结果与严格耦合波分析理论,计算得到了100~5 000eV能区光栅的绝对衍射效率曲线,并给出了错位双光栅的解谱方法.该错位双光栅能够有效提升透射光栅谱仪的性能,为高温等离子体诊断提供宽谱X射线时间分辨谱定量测量.     

透射光栅衍射率的实验标定和数值计算

简要介绍了实验室中使用的三种透射光栅的结构，在北京同步辐射源上实验标定了这些光栅的相对衍射效率。借助于光栅模型，得到了光栅的重要结构参数，并对光栅的绝对衍射效率进行模拟计算和讨论。     

3333lp/mm X射线透射光栅的研制

针对X射线透射光栅摄谱仪中的高线密度光栅,研究了采用电子束曝光和X射线曝光技术结合制作高线密度X射线透射光栅的工艺技术.首先利用电子束曝光和微电镀技术在镂空的薄膜上制备母光栅X射线掩模版,然后利用X射线曝光和微电镀技术小批量复制光栅.在国内首次完成了3333lp/mm X射线透射光栅的研制,栅线宽度为150nm,周期为300nm,金吸收体厚度为500nm.衍射效率标定的结果表明,该光栅的占空比合理、侧壁陡直,具有良好的色散特性,能够满足空间探测、同步辐射和变等离子诊断等多个领域的应用.     

透射光栅衍射效率的通用模型

在远场条件下采用夫朗和费衍射近似,经过波动光学的计算推导,得到透射光栅各级绝对衍射效率及相对衍射效率通用计算模型. 此模型可以用来计算任意栅线截面情况下透射光栅的衍射效率. 利用此模型,分别建立了矩形、梯形和5边准梯形截面的衍射效率计算模型,并对模型正确性进行了验证. 关键词： 透射光栅 衍射效率 数值模拟     

透射光栅衍射效率研究

透射光栅广泛应用于 X光能谱测量 ,为获得定量的 X光能谱 ,首先在北京同步辐射源上对透射光栅的衍射效率在多个入射 X光能量点进行了实验标定 ,获得了透射光栅衍射效率的实验结果。为模拟透射光栅衍射效率实验标定结果 ,发展了一个新的透射光栅衍射效率计算模型 ,该模型不同于国外已发展的矩形栅线模型和梯形栅线截面模型 ,而是假设透射光栅栅线具有准梯形截面。模型计算结果与实验标定结果符合很好。     

Geometrical layout and optics modelling of the surface science beamline station at the SESAME synchrotron radiation facility

The layout and the optical performance of the SGM branch of the D09 bending‐magnet beamline, under construction at SESAME, are presented. The beamline is based on the Dragon‐type design and delivers photons over the spectral range 15–250 eV. One fixed entrance slit and a movable exit slit are used. The performance of the beamline has been characterized by calculating the mirror reflectivities and the grating efficiencies. The flux and resolution were calculated by ray‐tracing using SHADOW. The grating diffraction efficiencies were calculated using the GRADIF code. The results and the overall shapes of the predicted curves are in reasonable agreement with those obtained using an analytical formula.     

小周期二元光学元件的矢量分析

详细地介绍了一种可用于分析大口径大视场二元光学系统的光栅矢量分析法－－ＢＫＫ 种方法适用于光栅周期处于波长量级、任意光栅轮廓及倾斜入射时的衍射率计算。给出 计算结果,并与标量近似计算结果进行比较 。     

Optimizing and characterizing grating efficiency for a soft X‐ray emission spectrometer

The efficiency of soft X‐ray diffraction gratings is studied using measurements and calculations based on the differential method with the S‐matrix propagation algorithm. New open‐source software is introduced for efficiency modelling that accounts for arbitrary groove profiles, such as those based on atomic force microscopy (AFM) measurements; the software also exploits multi‐core processors and high‐performance computing resources for faster calculations. Insights from these calculations, including a new principle of optimal incidence angle, are used to design a soft X‐ray emission spectrometer with high efficiency and high resolution for the REIXS beamline at the Canadian Light Source: a theoretical grating efficiency above 10% and resolving power E/ΔE > 2500 over the energy range from 100 eV to 1000 eV are achieved. The design also exploits an efficiency peak in the third diffraction order to provide a high‐resolution mode offering E/ΔE > 14000 at 280 eV, and E/ΔE > 10000 at 710 eV, with theoretical grating efficiencies from 2% to 5%. The manufactured gratings are characterized using AFM measurements of the grooves and diffractometer measurements of the efficiency as a function of wavelength. The measured and theoretical efficiency spectra are compared, and the discrepancies are explained by accounting for real‐world effects: groove geometry errors, oxidation and surface roughness. A curve‐fitting process is used to invert the calculations to predict grating parameters that match the calculated and measured efficiency spectra; the predicted blaze angles are found to agree closely with the AFM estimates, and a method of characterizing grating parameters that are difficult or impossible to measure directly is suggested.     

Theoretical models of diffraction efficiencies of arc profiled bar transmission grating

Diffraction efficiencies of transmission grating play important roles in accurate measurement of soft X-ray and grating applications. Circular, horizontal elliptical, and vertical elliptical arc profiled bar models were established from Kirchhoff diffraction theory with the Fraunhofer diffraction approximation to calculate the diffraction efficiencies of arc profiled bar transmission grating. The calculated results were compared with the available data from X-ray Optics web site of Lawrence Berkeley Laboratory's Center. Excellent agreements have been obtained. With these modes the diffraction efficiencies of the particular type of transmission grating having arc profiled bars can be simulated accurately and the best fit bar profiles can be obtained.     

DVD光学头中的梯形光栅设计和表面粗糙度分析

为了符合实际加工情形 ,推导了梯形位相光栅衍射效率 ,设计其用作 DVD光学头分光束器件时的各参数 ,并分析推导了表面粗糙度对衍射效率的影响     

亚波长光栅的偏振闪耀特性

 使用琼斯矩阵的方法推导了连续结构亚波长光栅的衍射方程,给出了光栅衍射效率表达式,对偏振特性与衍射特性进行了研究。发现连续结构亚波长光栅仅存在３个衍射级,总衍射效率为100%,且衍射效率可在衍射级间任意分配,0级的偏振态与入射光的偏振态相同,±1级衍射光偏振态与入射光无关,－1级为左旋圆偏振光,＋1级为右旋圆偏振光。通过设置入射光偏振态与光栅相位延迟等参数,可使光栅具有闪耀特性,据此可用于设计高效偏振光分束器和偏振光开关。