Speaker
Description
We report about the recent progress in imaging experiments performed at the DiProI end-station [1], the Coherent Diffraction Imaging (CDI) instrument of the FERMI seeded Free Electron Laser (FEL) user facility [2].
The mini-TIMER split and delay unit [3] offers the possibility to tomographically illuminate the sample from two different view angles, for stereoscopic imaging [4].
Several experiments took advantage of FEL beams carrying Optical Angular Momentum (OAM), either produced by the FERMI machine [5] or using conventional diffractive optics. We have studied the interaction of phase spiral beams with spin magnetic vortices ad their dynamics [6], showing that the far field scattering profile encodes the vortex symmetries in a way that depends on the sign and value of ℓ, giving rise to a new kind of magnetic helicoidal dichroism (MHD). Enhanced resolution has been demonstrated using OAM in diffraction-based imaging technique at FELs [7], showing how the speckles forming the diffraction pattern encode information on the light orbital angular momentum.
We also introduce multicolor “rainbow” Coherent Diffraction Imaging (CDI), taking advantage of recent advancements in multicolor FEL emission [8] to enable simultaneous probing of morphology and spectroscopic properties [9]. In the shown experiment, we explore multicolor imaging with FEL pulses, achieving spectroscopic imaging at five distinct wavelengths, ranging from 33 eV to 62 eV, by tuning the source undulators to different harmonics. Single-shot imaging was also demonstrated using three wavelengths simultaneously.
All the mentioned techniques have been applied or can be extended to the time-domain realm.
[1] Capotondi, Review of Scientific Instruments, 84 - 5, 051301 (2013). 10.1063/1.4807157
Capotondi, Journal of Synchrotron Radiation, 22, 544-552 (2015). 10.1107/S1600577515004919
[2] Allaria, Nature Photonics 6 (10), 699-704 (2012). 10.1038/nphoton.2012.233
Allaria, Nature Photonics 7 (11), 913-91 (2013). 10.1038/nphoton.2013.277
Rebernik Ribič, Nature Photonics 13 (8), 555-561 (2019). 10.1038/s41566-019-0427-1
[3] Bencivenga, Nature, 520 - 7546, 205-208 (2015). 10.1038/nature14341.
[4] Fainozzi, Optica, 10 - 8, 1053-1058 (2023). 10.1364/OPTICA.492730
[5] Rebernik Ribič, Physical Review X 7 (3), 031036 (2017). 10.1103/PhysRevX.7.031036
Morgan, Nature Photonics, 19 - 9, 946-951 (2025). 10.1038/s41566-025-01737-7
[6] Fanciulli, Physical Review A 103, 013501 (2021). 10.1103/PhysRevA.103.013501
Fanciulli, Physical Review Letters 128, 077401 (2022). 10.1103/PhysRevLett.128.077401
Fanciulli, Physical Review Letters, 134 - 15, 156701 (2025). 10.1103/PhysRevLett.134.156701
[7] Tamburini, Physical Review Letters 97, 163903 (2006). 10.1103/PhysRevLett.97.163903
Pancaldi, Optica, 11 - 3, 403-411 (2024). doi: 10.1364/OPTICA.509745
[8] Allaria, Nature Communications 4 (1), 1-7 (2013). 10.1038/ncomms3476
[9] Willems, Structural Dynamics, 4 - 1, 014301 (2017). 10.1063/1.4976004