Optical design and coating optimization of the Wolter-I X-ray telescope

The optical design of the nested paraboloid and hyperboloid Wolter I X-ray telescope of the eXTP satellite in the 1–8 keV band was systematically studied. The recursive relationship of nested structures is derived, and an analysis is conducted on the influence of initial parameters on performance. Considering the requirements of X-ray astronomical observation in China, we propose the initial structure of the model and design seven groups of Au/C/Ni non-periodic dual-layer coatings between the innermost and outermost layers of the mirror. The effective area, half-power diameter, and stray light were calculated in the simulation. The results show that the effective area can reach 1000cm 2 at 2 keV, the effective area can reach 890cm 2 at 6 keV without hub obscuration, the half-power diameter is 10 arcsec, and the proportion of stray light is 4.2%.