Department of Precision Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan.
The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
Rev Sci Instrum. 2023 Jan 1;94(1):015106. doi: 10.1063/5.0125242.
Abrasive machining has been used for inner surface processing of various hollow components. In this study, we applied an in-air fluid jet as a precision machining method for the inner surface of an axisymmetric x-ray mirror whose inner diameter was less than 10 mm. We employed an abrasive with a polyurethane@silica core-shell structure, which has a low density of about 1.2 g/cm and a relatively large particle size of about 15 µm. By using this abrasive, a practical removal rate and a smooth machined surface were simultaneously obtained. We performed figure corrections for an axisymmetric mirror and improved the circumferential figure accuracy to a sub-10 nm root mean square level. To evaluate the machining performance in the longitudinal direction of the ellipsoidal surface, we also performed periodic figure fabrication on the inner surface of a 114 mm-long nickel ellipsoidal mirror. X-ray ptychography, an optical phase retrieval method, was also employed as a three-dimensional figure measurement technique of the mirror. The wavefield of the x-ray beam focused by the processed ellipsoidal mirror was observed with the ptychographic system at SPring-8, a synchrotron radiation facility. The retrieval calculations for the wavefront error confirmed that a sinusoidal waveform with a period of 12 mm was fabricated on the mirror surface. These experimental results suggest that a nanoscale figure fabrication cycle for the inner surface consisting of jet machining and wavefront measurement has been successfully constructed. We expect this technique to be utilized in the fabrication of error-free optical mirrors and various parts having hollow shapes.
磨料加工已被用于各种中空部件的内表面加工。在这项研究中，我们将空气射流应用于直径小于 10mm 的轴对称 X 射线反射镜的内表面精密加工方法。我们使用了具有聚氨酯@二氧化硅核壳结构的磨料，其密度约为 1.2g/cm，相对较大的粒径约为 15μm。通过使用这种磨料，同时获得了实际的去除率和光滑的加工表面。我们对轴对称反射镜进行了形貌校正，并将圆周轮廓精度提高到亚 10nm 均方根水平。为了评估在椭圆表面的纵向方向上的加工性能，我们还在 114mm 长的镍椭圆反射镜的内表面上周期性地制造了形貌。X 射线相衬成像技术，一种光学相位恢复方法，也被用作反射镜的三维形貌测量技术。在 SPring-8 同步辐射设施中的相衬系统中，观察了由处理后的椭圆反射镜聚焦的 X 射线束的波场。用于波前误差的检索计算证实，在镜面上制造了具有 12mm 周期的正弦波形。这些实验结果表明，已经成功构建了由射流加工和波前测量组成的内表面纳米级形貌制造周期。我们期望这项技术能够用于制造无误差的光学反射镜和各种具有中空形状的零件。
