produced by a table-top source. The light scattered from the object MODELING, METHODOLOGY was recorded by a charge-coupled device (CCD) camera set at 16 AND INSTRUMENTATION mm from the sample. Compared to the narrowband diffraction pattern SYNCHROTRON SOLEIL HIGHLIGHTS 2020 (Fig. 1.b), the broadband diffraction pattern is blurred (Fig. 1.c). Our monochromatization method applied to the broadband pattern has successfully recovered the mains characteristics observed in the NANOSCOPIUM BEAMLINE monochromatic case (Fig 1.d). Phase retrieval based on the difference map method with a shrink-wrap-like support was performed on these Associated publication diffraction patterns (Fig. 1.f-h). Whereas the CDI algorithm does not reach convergence when using the broadband diffraction pattern (Fig. 1.g), Broadband coherent diffraction for the sample is readily reconstructed for both the monochromatic (Fig. 1.f) single-shot attosecond imaging. and numerically monochromatized cases (Fig. 1h). J. Huijts, S. Fernandez, D. Gauthier, M. Kholodtsova, A. Maghraoui, BROADBAND HARD X-RAY ILLUMINATION K. Medjoubi, A. Somogyi, W. Boutu, To test our method in the hard X-ray regime, we measured a Siemens and H. Merdji star of 20-μm total diameter at the NANOSCOPIUM beamline of SOLEIL Nature Photonics 14, 618 (2020). synchrotron (France) [4]. A broadband source of 12% bandwidth was emulated by summing monochromatic diffraction patterns collected References at successive energies, ranging from 7.1 to 8.0 keV in steps of 4 eV. [1] J.W. Miao et As shown in Fig. 2.a, the broadband diffraction pattern is blurred and al. , Nature 400, does not present the features that would be expected for a coherently 342 (1999). illuminated object, i.e. the frequency modulation of the streaks arising [2] H. N. Chapman, Nature materials, 8, 299 (2009). from the spokes. The result of the monochromatization process shown in [3] A. Ravasio et a , Phys. Rev. Lett.l. Fig. 2.b exhibits sharp features and interference fringes. Phase retrieval 103, 028104 (2009). was then performed using the PyNX package [5]. Fig 2.c shows the [4] A. Somogyi et al., J. Synchrot. reconstructed magnitude of the sample from the monochromatized Radiat. 22, 1118 (2015). [5] O. Mandula et al., J. Appl. broadband pattern. For comparison, the same phase retrieval procedure Crystallogr. 49, 1842 (2016). was applied to a single monochromatic diffraction pattern (at 7.1 keV), shown in Fig. 2.d. Corresponding authors FIGURE 2 Hamed Merdji LIDYL, CEA, CNRS, Université Paris-Saclay, CEA Saclay, Gif-sur-Yvette. hamed.merdji@cea.fr Kadda Medjoubi Synchrotron Soleil, Gif-sur-Yvette, France. Kadda.Medjoubi@ synchrotron-soleil.fr Captions FIGURE 1: Experimental validation in the visible spectrum. a, The broadband spectrum (orange) with a bandwidth of Δλ/λ = 11% and the narrowband spectrum (blue) with a bandwidth of Δλ/λ = 1.2%. b, Narrowband diffraction pattern. c, Broadband diffraction pattern. d, Monochromatized diffraction pattern from the broadband data in c. e, SEM image of the sample. Scale bar, 10 μm. f, Reconstruction for the narrowband case. g, CDI reconstruction directly from the broadband pattern in c. h, Reconstruction of the monochromatized diffraction pattern in d. DISCUSSION FIGURE 2: X-ray experimental validation using synchrotron We have demonstrated successful image reconstruction from broadband radiation. a, Broadband diffraction pattern obtained by summing all the acquired monochromatic diffraction coherent diffraction patterns, paving the way towards single-shot attosecond patterns. b, Diffraction pattern obtained after numerical lensless imaging and synchrotron pink beam coherent diffraction imaging. monochromatization of the diffraction pattern in a. c, Reconstructed amplitude of the Siemens star sample from The method can be applied to any technique based on coherent elastic the monochromatized broadband diffraction pattern in b. d, scattering with any type of coherent radiation. Furthermore, since our Reconstructed amplitude of the same object from a single monochromatic diffraction pattern. technique is applied as a step before the phase retrieval process itself, both single-shot CDI and pink beam ptychography could benefit from it. 87