摘要:
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%.
Abstract:
Due to its attractive features such as compact size, simple to align and wide working range of photon energy, the X-ray compound refractive lens (CRL) has gradually become one of the standard accessories to focus the X-ray beams from the synchrotron radiation light source. In this paper, a cascaded planar parabolic CRL is designed and fabricated. The novel CRL is composed of type I and type II refractive elements in order to achieve a small spot size while maintaining the transmission. In type I refractive element, the parabolic geometry aperture (R0) is large, while, in type II refractive element, the radius of curvature (R) at the parabolic vertex is small. So N1 numbers of type I and N2 numbers of type II refractive elements are cascaded to form a single-chip CRL. A cascaded X-ray planar parabolic CRL is constructed using PMMA material by means of LIGA techniques. The main structural parameters of type I refractive elements are:N1 =15, R1 =200 μm, 2R01 =564 μm. The main structural parameters of type II refractive elements are: N2 =20, R2 = 50 μm, 2R02 = 140 μm. The cascaded planar parabolic CRL is tested on the beam line whose original incident X-ray spot is 200 μm × 100 μm at Shanghai synchrotron radiation facility. The measured lateral focusing spot size is 24.9 μm@8 keV, the transmission rate is 2.19%and the focal length is 1.052 m.
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