镍基棱镜型高能X射线聚焦组合折射透镜的研制

Fabrication of Nickel Prism-Array Combined Refractive Lenses for High-Energy X-Ray Focusing

组合折射透镜是聚焦高能X射线(能量大于50keV)的主要聚焦元件,因此成为同步辐射聚焦技术的研究的前沿与热点。为实现优异的聚焦性能,透镜的优化设计是前提,优良的制备工艺是保证和关键。我们研制了一种棱镜型的高能X射线聚焦组合折射透镜,透镜整体由5280个齿状结构组合而成,最小的特征尺寸为10μm,口径为1.77 mm。利用LIGA技术,成功完成高度为500μm的镍基棱镜型高能X射线组合折射透镜的制备。为保证透镜良好尖角结构,在制备过程中采用电子束直写并且逐步加大掩膜版厚度的方法,先后制备了过渡掩膜版和LIGA掩膜版,保证了透镜良好的形貌,尖角略有钝化。在上海光源X射线成像及生物医学应用光束线(BL13W1)完成了透镜的在线测试,结果表明:该透镜将50 keV的X射线聚焦到7.7μm,增益为14倍。

Combined refractive lens is the main focusing element for focusing high-energy X-ray(>50 keV),which is presently the frontier and hot topic of research of focusing technique for synchrotron radiation.For focusing lens,the optimization theoretical design is the premise,while the satisfactory fabrication process is the guarantee and key to excellent performance.A kind of prism type high-energy X-ray focusing composite refractive lens is designed and fabricated,which is composed of 5280 tooth-like segments structures with the minimum characteristic size of 10μm and aperture of 1.77 mm.The prism lenses for focusing high-energy X-rays with depth of 500μm has been successfully fabricated by LIGA technology.To ensure the good sharp-angle structure of the lens,the transition mask is prepared using the direct writing by electron beam method,and the thickness of the mask increases gradually,so as to ensure the good morphology of the lens.There is a little passivation at the sharp corner of the final sample.The focusing performance of prism-array lenses is characterized by at knife-edge scan method at the X-ray Imaging and Biomedical Application Beamline BL13 W1 at Shanghai Synchrotron Radiation Facility,and provided a focal width of 7.7μm and a photon flux gain of 14 at an X-ray energy of 50 keV.