Replication of Wolter I shaped surface on a two-stage thin-foil substrate

Abstract

We have developed advanced thin-foil substrates with a two-stage reflector for a large X-ray telescope. We successfully formed a magnesium foil with a figure error of a peak-to-peak value of 60 µm. This figure error has allowed a replication method in order to obtain smooth surface. We made a glass mandrel precisely shaped Wolter type-I optics by using the ELID method, then applied the replication to a 200 mm length aluminum foil at Nagoya University. After the replication, the figure error of the foil was improved by as much as factor 10. We evaluated the image quality of the replicated foil by using a collimated optical light at Ehime University, and we demonstrated the potential of the replication method. We report a current status of the development of the replication method.