Fig. 1. Schematic diagrams of bent spectrometers. (a) Principle of single Bragg diffraction; (b) principle of double diffraction

Fig. 2. Analysis results of energy segments for different orientation of diamond and silicon crystals. (a) Bragg diffraction angle for diamond in energy range of 3--25 keV; (b) Bragg diffraction angle for silicon crystals in energy range of 3--25 keV

Fig. 3. Diagrams of working principles of double diffraction spectrometer. (a) 3--6 keV; (b) 5.5--10 keV; (c) 10--20 keV; (d) 17--25 keV

Fig. 4. Position sweep trajectories of rotation center of crystal 2 and detector center of double diffraction spectrometer in each energy range (taking rotation center O of crystal 1 as origin of coordinate)

Fig. 5. Theoretical resolution of single and double Bragg diffraction for bent C(220) crystal and bent C(440) crystal when R₁=R₂=0.1 m, D₂=0.5 m, and p=20 μm. (a)(c) L₂=0.2 m; (b)(d) L₂=0.1, 0.2, 0.3 m

Fig. 6. Bandwidth of double diffraction spectra and data points in bandwidth. (a) Three-dimensional image of bandwidth for single Bragg diffraction when R=0.1 m; (b) bandwidth for double Bragg diffraction at different photon energy(empty square represents number of data points within bandwidth obtained by double Bragg diffraction); (c) typical SASE spectrum including multiple spikes; (d) schematic diagram of data points measured at several different energy within single spike

Fig. 7. Monochromatic light analysis results at different Darwin angular width when R=0.1 m and t=20 μm. (a) 30°; (b) 45°; (c) 60°