级联式平面抛物面型X射线组合折射透镜的设计与制作

X射线组合折射透镜(CRL)已逐步成为同步辐射光源下X射线聚焦光学器件的标准配件之一,它具有结构紧凑、易调节校准、适用光子能量范围大等优点.本文设计了一种级联式平面抛物面型CRL,它将N1个具有较大抛物面几何孔径(R0)的折射单元I与N2个具有较小抛物面顶点曲率半径(R)的折射单元II级联,以解决常规CRL设计过程中焦斑尺寸与透过率的矛盾.采用PMMA材料,利用LIGA技术制作了一组级联式平面抛物面型CRL,其中折射单元I的主要结构参数为N1=15,R1=200μm,2R01=564μm;折射单元II的主要结构参数为N2=20,R2=50μm,2R02=140μm.在上海光源同步辐射线束上,所制作的级联式平面抛物面型CRL实现了对初始光斑尺寸为200μm×100μm的入射X射线的一维聚焦,测试得到的焦距为1.052 m,横向焦斑尺寸为24.9μm@8 keV,透过率为2.19%.     

制作工艺误差对X射线组合折射透镜聚焦性能影响研究

本文主要介绍对X射线组合折射透镜的制作工艺误差对其聚焦性能影响的研究结果. 首先给出采用深度X射线光刻技术制作的PMMA材料圆柱面型X组合折射透镜的工艺测试结果,得出制作工艺误差值,定性分析制作工艺误差对X射线组合折射透镜聚焦性能的影响. 然后根据实际的制作工艺误差建模,给出详尽的理论分析和定量的理论模拟结果. 最后在北京同步辐射装置(BSRF)上,构建基于PMMA材料的圆柱面型X射线组合折射透镜的微束聚焦实验系统,实际测试了有明显工艺误差和尽量消除工艺误差的两种X射线组合折射透镜的聚焦性能,给出实测结果 关键词： X射线组合折射透镜 制作工艺误差 X射线聚焦性能 同步辐射     

抛物面型X射线组合折射透镜聚焦性能的理论与实验研究

结合衍射理论和矩阵光学方法得出抛物面型X射线组合折射透镜的光学性能指标(包括其焦距的严格表达式、薄透镜近似的判定准则、透过率和有效孔径,以及极限聚焦光斑尺寸等).采用X射线深度光刻技术实际制作了PMMA材料抛物面型X射线组合折射透镜并给出了工艺测试结果.最后在北京同步辐射装置(BSRF)上,实际构建了基于3种不同结构参数的PMMA材料抛物面型X射线组合折射透镜的微束聚焦实验系统.并实际测试了其聚焦性能,均获得了良好的聚焦效果,给出实测结果并对实测结果进行了分析和讨论.     

Application of the probability theory in predicting 3D focusing behaviors of compound X-ray refractive lenses

A theoretical method based on the diffractive theory is used for predicting three-dimensional (3D) focusing performances of the compound X-rays refractive lenses (CRLs). However, the derivation of the 3D intensity distribution near focus for the X-ray refractive lenses is quite complicated. In this paper, we introduce a simple theoretical method that is based on the first and second moments in the theory of probability. As an example, the 3D focusing performance of a CRL with Si material is predicted. Moreover, the results are compared with those obtained by the diffractive theory. It is shown that the method introduced in this paper is accurate enough.     

复合折射透镜的进展和应用

文章介绍了X射线复合折射透镜的工作原理,详细回顾了X射线复合折射透镜的发展历程,综述了近年来X射线复合折射透镜的研究成果及其主要应用领域.     

A theoretical method based on Fourier spectrum analysis for the focusing performances of the X-ray compound refractive lenses

It is important to predict the intensity distribution in focusing plane for designing the X-ray compound refractive lenses. On the basis of analyzing the structure of X-ray compound lenses and comparing it with Fraunhofer diffraction system, it is concluded that the X-ray focusing system can be regarded as a kind of Fraunhofer diffraction system. Therefore, a method based on Fourier spectrum analysis is presented to predict the intensity distribution in the focusing plane for the X-ray lenses. A brief analysis on the relationship between the parameters of X-ray lenses and their focusing performance is also given in this paper.     

A method based on diffraction theory for predicting 3D focusing performance of compound refractive X-ray lenses

A method based on the diffraction theory for estimating the three-dimensional (3D) focusing performance of the compound refractive X-ray lenses is presented in this paper. As a special application, the 3D X-ray intensity distribution near the focus is derived for a plano-concave compound refractive X-ray lens.Moreover, the computer codes are developed and some results of 3D focusing performance for a compound refractive X-ray lens with Si material are shown and discussed.     

Effective aperture of X‐ray compound refractive lenses

A new definition of the effective aperture of the X‐ray compound refractive lens (CRL) is proposed. Both linear (one‐dimensional) and circular (two‐dimensional) CRLs are considered. It is shown that for a strongly absorbing CRL the real aperture does not influence the focusing properties and the effective aperture is determined by absorption. However, there are three ways to determine the effective aperture in terms of transparent CRLs. In the papers by Kohn [(2002). JETP Lett. 76 , 600–603; (2003). J. Exp. Theor. Phys. 97 , 204–215; (2009). J. Surface Investig. 3 , 358–364; (2012). J. Synchrotron Rad. 19 , 84–92; Kohn et al. (2003). Opt. Commun. 216 , 247–260; (2003). J. Phys. IV Fr, 104 , 217–220], the FWHM of the X‐ray beam intensity just behind the CRL was used. In the papers by Lengeler et al. [(1999). J. Synchrotron Rad. 6 , 1153–1167; (1998). J. Appl. Phys. 84 , 5855–5861], the maximum intensity value at the focus was used. Numerically, these two definitions differ by 50%. The new definition is based on the integral intensity of the beam behind the CRL over the real aperture. The integral intensity is the most physical value and is independent of distance. The new definition gives a value that is greater than that of the Kohn definition by 6% and less than that of the Lengeler definition by 41%. A new approximation for the aperture function of a two‐dimensional CRL is proposed which allows one to calculate the two‐dimensional CRL through the one‐dimensional CRL and to obtain an analytical solution for a complex system of many CRLs.     

X-ray focusing with compound lenses made from beryllium

We have measured the intensity profile and transmission of x rays focused by a series of biconcave spherical unit lenses fabricated from beryllium. The use of beryllium extends the range of operation of compound refractive lenses, improving transmission, aperture size, and gain. The compound refractive lens was composed of 160 biconcave unit lenses, each with a radius of curvature of 1.9 mm. Two-dimensional focusing with a gain of 1.5 was obtained at 6.5 keV with a focal length of 93 cm. The effective aperture of the compound refractive lens was measured as 600 mum , with 9% peak transmission.     

Large‐acceptance diamond planar refractive lenses manufactured by laser cutting

For the first time, single‐crystal diamond planar refractive lenses have been fabricated by laser micromachining in 300 µm‐thick diamond plates which were grown by chemical vapour deposition. Linear lenses with apertures up to 1 mm and parabola apex radii up to 500 µm were manufactured and tested at the ESRF ID06 beamline. The large acceptance of these lenses allows them to be used as beam‐conditioning elements. Owing to the unsurpassed thermal properties of single‐crystal diamond, these lenses should be suitable to withstand the extreme flux densities expected at the planned fourth‐generation X‐ray sources.     

铜材料X射线聚焦组合透镜的设计与制作

铜材料X射线聚焦组合透镜是一种基于折射效应的X射线聚焦元件。简单介绍了组合透镜的设计理论研究结果,并据此对材料作了选择。针对铜材料组合透镜,分析了组合透镜结构参数、X射线工作波长的选择对组合透镜光学性能的影响。在此基础上,设计了组合透镜的结构参数,使其在硬X射线波段具有较好的聚焦性能,并能获得较高的焦斑强度。采用准LIGA技术制作了铜材料X射线组合透镜,给出了部分铜材料X射线组合透镜结构测量结果。     

用于X射线激光实验研究的列阵柱面透镜线聚焦系统

用平行排列的柱面透镜列阵与非球面会聚透镜组成一个新颖的激光线聚焦系统,它能获得光强分布非常均匀的、能应用于X射线激光实验研究的高功率激光焦线。实验证明该聚焦系统有良好的特性。     

背面曝光技术制作沙漏状X射线组合折射透镜

在分析沙漏状X射线组合折射透镜（X-ray compound refractive lens,XCRL）的折射聚焦理论的基础上,设计并利用背面曝光技术制作了SU-8材料的沙漏状XCRL,该技术在保证图形准确性的同时减少了工艺步骤,使制作更加简便易行.在10?keV单色X射线辐射下,对制作的透镜进行了聚焦性能的实验测试,结果表明,所制作的透镜较好地实现了一维聚焦. 关键词： 组合折射透镜 背面曝光 沙漏状 SU-8     

Waveguide optical planar lenses in LiNbO3 — Theory and experiments

A simple, efficient method for the fabrication of a waveguide optical planar lens is reported. The method is based upon the Ti-indiffusion (TI), proton-exchange (PE), and Ti-indiffusion—proton-exchange (TIPE) techniques in LiNbO₃ substrates. The effective refractive indices of the TI waveguide are very different. Starting with Fermat's principle a non-spherical contour lens can be designed. The experimental result of an F = 15 mm dual lens is described, the focal characteristic of which is excellent.     

Eikonal approximation in the theory of X-ray interferometer

On the basis of eikonal approximation a theory of X-ray moiré formation is presented in the case where deformations are present in all three plates of the interferometer. The role of each plate of the interferometer in the process of moiré formation is revealed. The theory can be applied for the general case of weak deformations.     

Analysis of lateral-spread photorefractive planar lenses

The photorefractive planar lens for converting a vertical incident plane wave to a lateral-spread spherical wave and vice versa, is suggested. Using the two-beam coupled-wave theory, the coupled wave equations are derived and their half-analytical solutions are also given in terms of an infinite series. The diffraction properties (beam profiles, diffraction efficiency) of the local volume grating in the lens are presented. And the focusing property of the lens is discussed and compared with that of an ideal convergent spherical wave. It is demonstrated that the suggested photorefractive planar lens shows a good focusing effect.     

X-ray phase-sensitive microscope imaging with a grating interferometer: Theory and simulation

A general theoretical framework is presented to explain the formation of the phase signal in an x-ray microscope integrated with a grating interferometer, which simultaneously enables the high spatial resolution imaging and the improved image contrast. By using this theory, several key parameters of phase contrast imaging can be predicted, for instance, the fringe visibility and period, and the conversion condition from the differential phase imaging (DPI) to the phase difference imaging (PDI). Additionally, numerical simulations are performed with certain x-ray optical components and imaging geometry. Comparison with the available experimental measurement [Appl. Phys. Lett. 113 063105 (2018)] demonstrates the accuracy of this developed quantitative analysis method of x-ray phase-sensitive microscope imaging.     

Fabrication of gradient refractive index ball lenses

The theoretical model of the Maxwell fish eye sphere lens has long been regarded as an absolute optical instrument without practical application since it was proposed. But the study on the theory of Maxwell fish eye micro-spherical lens shows that at certain condition it has fine image formation ability and coupling efficiency. Based on the Fick's diffusion equations, the distribution function of refractive index of gradient refractive index (GRIN) ball lenses is derived. Lithium-containing silicate glass is fabricated and GRIN ball lenses whose diameters are from 0.3 to 3.0 mm are made by ion exchange and the sagging method in sodium nitrate. Radial refractive index profiles of these GRIN ball lens are measured by interferometer. Results show that the distribution of the index of refraction is a parabolic curve and in concordance with the computational consequence and its Δn is 0.0002.     

A series of microscope objective lenses combined with an interferometer for individual nanoparticles detection

In this paper, we uniquely introduce a series of microscope objectives (MOs) combined with a polar interferometer for imaging individual nanoparticles in real-time. The MOs with cascade magnifications are used to magnify the individual nanoparticle interferogram in the entire field of the CCD camera. Single shot, interferogram is captured and then reconstructed by the angular spectrum method. Size of the individual nanoparticle is then calculated by a simple geometric optical equation. Using this technique, important applications in drug delivery that require precision in size and shape of nanocarriers can be demonstrated. Moreover, using this technology, biological samples with birefringence can be investigated precisely.     

X‐ray harmonics rejection on third‐generation synchrotron sources using compound refractive lenses

A new method of harmonics rejection based on X‐ray refractive optics has been proposed. Taking into account the fact that the focal distance of the refractive lens is energy‐dependent, the use of an off‐axis illumination of the lens immediately leads to spatial separation of the energy spectrum by focusing the fundamental harmonic at the focal point and suppressing the unfocused high‐energy radiation with a screen absorber or slit. The experiment was performed at the ESRF ID06 beamline in the in‐line geometry using an X‐ray transfocator with compound refractive lenses. Using this technique the presence of the third harmonic has been reduced to 10^?3. In total, our method enabled suppression of all higher‐order harmonics to five orders of magnitude using monochromator detuning. The method is well suited to third‐generation synchrotron radiation sources and is very promising for the future ultimate storage rings.