Development of a numerically controlled elastic emission machining system for fabricating mandrels of ellipsoidal focusing mirrors used in soft x-ray microscopy

摘要

Ellipsoidal mirrors are one of the most promising types of X-ray mirror, because the mirror can focus X-rays to nanometer size with a large aperture and no chromatic aberration. However, so far ideal ellipsoidal mirrors cannot be realized by any manufacturing methods. One of the reasons is there is no fabrication method to process their inside surface with a diameter of several millimeters with nanometer-level accuracy. We propose and develop a manufacturing process of the ellipsoidal mirror. First, a master which has the reversed shape is prepared using grinding, polishing and Elastic Emission Machining (EEM). EEM can finish the surface shape to within 2nm (RMS). Then, the ellipsoidal mirror is produced by replicating the surface using an electroforming deposition method. By conducting the process without any stress at room temperature, replicating the surface roughness and shape with nanometer order accuracy is possible. In this paper, we report the current status of manufacturing of the ellipsoidal mirror.