Development of x-ray focusing telescope by thin-glass slumping technology

The imaging x-ray telescope (IXT) has been developed for over a decade at the Institute of Precision Optical Engineering of Tongji University. Since then, we have made great progress on the development of mirror fabrication, coatings, and optic assembly. In this paper, we intend to provide an overview of the progress. Currently, we can routinely produce cylindrical mirror substrates with angular resolution of 16″ to 35″. To improve the effective area, coatings using C, Ni, and Pt layers were designed and achieved a high reflectivity at 0.5 to 10 keV. During the optic assembly, an in-situ measurement system and a three-dimensional ray-tracing program have been developed to guide the assembly process in real time. Several prototypes have been calibrated at the MPE PANTER x-ray test facility in Germany. An IXT prototype with 21 layers was calibrated at the PANTER X-ray test facility, indicating an HPD of 111″ and effective area of 39 cm2 at 1.49 keV in August 2018. Now the latest prototype with 3 layers was calibrated indicating an HPD of 58″ at 1.49 keV in September 2019.