Development of X-Ray Multilayer Aspheric Mirrors by Replication Technology and Nano-Structure Analysis

在玻璃圆筒上沉积Pt/C多层膜后，在其上粘上铝箔，并在红外加热的真空室中固化。将镀在铝箔上的铂/碳多层反射镜从玻璃筒中分离出来，作为复制的薄片反射镜应用于硬x射线望远镜。该望远镜在美国被气球发射了几次，用于观测太空中的硬x射线物体。在表面涂覆Pt/C多层膜，再用环氧树脂粘接在平整的草皮板上，使Pt/C多层膜与化学镀镍表面完美分离。化学镀镍表面粗糙度为0.14nm， Pt/C多层反射镜表面粗糙度为0.16nm。通过高分辨透射电镜（TEM）对硅片上镀覆的Pt/C多层膜进行截面观察，发现C层呈非晶结构，Pt层呈取向多晶纳米结构，导致两层界面处表面粗糙度增大。在Pt/C多层材料中，层间距小于3nm时，界面粗糙度随层间距的减小而增大。通过在化学镍非球面模具和第一层Pt之间添加中间Ti层，将Pt/C多层膜从化学镍模具中分离出来，获得了用于硬x射线应用的Pt/C多层复制内镜。利用该技术制作了直径为6 mm的镀金非球面内镜，得到了形状精度为72nm、表面粗糙度为1nm的非球面x射线复制收集镜。然后制作图像分辨率小于50nm的软x射线显微镜。

After depositing Pt/C multilayer on a glass cylinder, we glued aluminum foil on it and cured in a vacuum chamber with an infrared heater. Pt/C multilayer mirrors on aluminum foils were separated from the glass cylinder and were used in a hard X-ray telescope as replicated thin foil mirrors. The telescope was lunched several times in U.S.A.by balloons for observing hard X-ray objects in a space.The float-polished electroless nickel plane was coated with Pt/C multilayer and glued with a flat grass plate using epoxy resin, and we could separate the Pt/C multilayer from the electroless nickel plane perfectly. The surface roughness was 0.14nm rms on the electroless nickel plane and 0.16nm rms on the Pt/C multilayer mirror, respectively.The high resolution transmission electron microscopy (TEM) sectional observation of Pt/C multilayer coated on a silicon wafer cleared that C layer showed an amorphous structure and Pt layer showed an oriented polycrystalline nano structure which causes the surface roughness at the interface between two layers. The interface roughness is increased with the decrease of layer spacing less than 3nm in the Pt/C multilayer.By adding an intermediate Ti layer between the electroless nickel aspheric die and the first Pt layer, we could separate the Pt/C multilayer from the electroless nickel die and obtain Pt/C multilayer replicated internal mirrors for hard X-ray application.This technology was used in making a gold plated aspheric inner mirror of 6 mm in diameter and we obtained aspheric X-ray replicated collecting mirrors of 72nm in shape accuracy and 1nm Ra in surface roughness. Then we made a soft X-ray microscope of less than 50nm in image resolution.