Fig. 1. Development history of hard X-ray focusing below 100 nm in the last two decades

Fig. 2. Schematic diagram of zone plate^[24]. (a) Structure of zone plate; (b) double zone plate resist template coated with Ir

Fig. 3. Schematic diagram of multilayer Laue lens. (a) Tilted multilayer Laue lens focusing; (b) optimization by wedged module

Fig. 4. Schematic diagram of refractive lens. (a) X-ray beam propagation in single refractive lens; (b) scanning electron microscope image of nanofocusing parabolic refractive X-ray lenses^[49]

Fig. 5. Schematic diagram of Kinoform lens. (a) Schematic diagram of lens array with graded apertures^[54]; (b) scanning electron microscope image of refractive lens with “fern-like” profile^[53]

Fig. 6. Schematic diagram of K-B mirror focusing^[58]. (a) K-B mirror with standard mode; (b) K-B mirror with Montel mode

Fig. 7. Schematic diagram of working principle of waveguide^[78]. (a) Beam propagation in tapered waveguide; (b) experimental layout (entrance side of waveguide is located at focal plane of K-B mirror); (c) far-field imaging of exit beam

Fig. 8. Magnified Talbot self-imaging obtained by single-grating interferometer characterizing wavefront characteristics of focusing system

Fig. 9. Schematic diagrams of two kinds of one-dimensional speckle scanning measurement. (a) Upstream mode; (b) downstream mode

Fig. 10. Experiment based on speckle statistics^[71]. (a) Experimental setup of speckle interferometry; (b) Speckle patterns and their autocorrelation functions

Fig. 11. Experimental diagram for characterization of focused beam produced by K-B mirror^[113]

Fig. 12. Reconstruction of sample and incident wavefront by ptychography^[114]. (a) Sample; (b) incident wavefront

Fig. 13. Schematic diagram of iterative phase retrieval method. (a) Wavefront in vicinity of beam waist and diffracted X-ray recorded by detector in dark field^[118]; (b) phase iterative realized by angular spectrum propagation between multiple wavefronts near focal spot^[83]

Fig. 14. Wavefront aberrations of shape of K-B mirror before and after correction^[119]. (a) Horizontal focusing mirror; (b) vertical focusing mirror

Fig. 15. Working principle of piezoelectric deformable focusing mirror. (a) Schematic diagram of piezoelectric deformable focusing mirror; (b) piezoresponse functions of piezoelectric deformable mirror with 18 channels

Fig. 16. Schematic diagram of phase compensation mirror developed by Osaka university^[133]

Fig. 17. Effect of phase compensation mirror on focusing. (a) Perfect focusing obtained by deformable mirror; (b) comparison of surface profile of deformable mirror (upper) and focal spot size (lower) before and after phase compensation^[66]

Fig. 18. Wavefront compensation of beryllium compound refractive lens realized by using phase plate^[138]. (a) Deformation of every lens surface; (b) comparison between surface profile and design goal of SiO₂ phase plate

Fig. 19. Schematic diagram of two structure sequences of refractive phase plate^[140]