FABRICATION OF WOLTER-TYPE X-RAY FOCUSING MIRROR USING EPOXY-RESIN

We have developed a new fabrication method for Welter-type x-ray focusing mirrors. In this method, a slight gap between the master mandrel and the glass replica produced by vacuum replication was filled with epoxy resin to decrease the roughness and the figure displacement of the minor surface. The mirror was evaluated both by taking x-ray microphotographs of No. 1000 and No. 2000 copper meshes with Al K alpha and C K alpha x rays, and by focusing x rays with several wavelengths using synchrotron radiation. No apparent degradation was found in the micrographs even when we changed the irradiating x rays from the C K alpha to the Al K alpha. The focused beam profile remained unchanged even at the wavelength of 1.24 nm. The beam size in the meridional plane also decreased to 50% of the beam size focused by a mirror fabricated only by vacuum replication. These results indicate that the present method successfully decreases the surface roughness to less than 6.2 nm (peak-to-valley) and improves the figure accuracy of the mirror surface.