Development of the light-weight X-ray mirror using carbon fiber reinforced plastic and ultra-precision machining technology

Light-weight X-ray mirrors with a high-angular resolution and a large effective area are required to clarify the physical mechanism of the coevolution of galaxies and black holes. To realize such X-ray mirrors, we are developing X-ray mirrors using the carbon fiber reinforced plastic (CFRP); CFRP is a light, but strong material, and it can be processed into a variety of shapes. However, CFRP has a finely textured surface, which is called print through. The surface is too rough to reflect X-rays due to the print though. In order to mitigate the print through, we developed a method to form a thin amorphous NiP layer on the surface of CFRP. Then the NiP surface was finished by ultra-precision machining technology to achieve sufficient surface roughness to reflect X-rays. An X-ray reflectivity measurement for a prototype CFRP-NiP flat mirror using the ISAS X-ray beam line confirmed that the surface roughness was sufficient to reflect X-rays of a few keV. We are also developing the prototype of the Wolter-I type mirror, which is reported in this talk.