Compact full-field hard x-ray microscope based on advanced Kirkpatrick–Baez mirrors

Abstract

X-ray full-field microscopy is a promising method for nondestructive observation of opaque materials because it can attain a high resolution and wide field of view without sample scanning. We recently developed hard x-ray objective optics, which are key devices for full-field microscopy, based on total-reflection mirrors with high throughput and achromatic properties. The objective optics consist of two types of advanced Kirkpatrick–Baez mirrors configured as crossed one-dimensional Wolter type I and type III optics. The designed optics possessed magnification factors of 42–45 with a compact camera length of approximately 2 m. The hard x-ray full-field microscope based on this system was tested at the BL29XU beamline at SPring-8. We were able to resolve 100-nm periods (50-nm line widths) of a resolution test chart at a photon energy of 15 keV over 30 h, which demonstrated the remarkable stability of this system. The image quality was preserved over a wide photon energy range from 9 to 15 keV. A periodic dot pattern with dot diameters of 300 nm, formed on a 775-µm-thick Si substrate, was three-dimensionally visualized by computed tomography.