Development of concave-convex imaging mirror system for a compact and achromatic full-field X-ray microscope

A full-field X-ray microscope utilizing advanced Kirkpatrick-Baez optics, which comprises four concave mirrors, provides high-resolution X-ray images without chromatic aberration. However, a large distance is required between the mirrors and the detector to obtain sufficiently high magnification factor. To achieve reduce this distance, this paper proposes a novel X-ray imaging mirror system consisting of two pairs of concave and convex mirrors, which enables the effective focal length to be decreased by shifting the principal surface. For developing the proposed optics, the mirrors were fabricated with an ion beam figuring system and stitching interferometer, developed by our group, with a peak-to-valley accuracy of similar to 2 nm. Analysis results indicate that the fabricated mirrors can achieve nearly diffraction-limited imaging performance. We report the mirror fabrication results and the characteristics of the fabricated mirrors.