Development of an ultra-high precision X-ray telescope with an adaptive optics system

摘要

We are developing an ultra high precision Soft X-ray telescope. The design of the telescope is a normal incident one for 13.5nm band using Mo/Si multilayers. Two ideas are introduced. One is the optical measurement system in order to monitor the precision of the optics system. The other is the adaptive optics system with a deformable mirror, Using an X ray-optical separation filter, we can always monitor the deformation of the optics by optical light. With this information, we can control the deformable mirror to compensate the system deformation as a closed loop system. We confirmed that the absolute precision of the wave front sensor was less than 3 nm rms. The precision of the deformable mirror was roughly 5 nm rms. The shape of the primary mirror was an off-axis paraboloide with an effective diameter of 80mm. This primary mirror was coated by Mo/Si multilayers. The reflectivity of the primary mirror at 13.5nm was ranging from 30 to 50%. The X ray-optical separation filter was made from Zr with a thickness of ～170nm. The transmission of the filter for low energy X-ray was measured and was roughly 50 % at 13.5nm.