Strict requirement of a coherent spectrum in coherent diffractive imaging (CDI) architectures poses a significant obstacle to achieving efficient photon utilization across the full spectrum. To date, nearly all broadband computational imaging experiments have relied on accurate spectroscopic measurements, as broad spectra are incompatible with conventional CDI systems.
We present an advanced approach to broaden the scope of CDI to ultra-broadband illumination with unknown probe spectrum, effectively addresses the key challenges encountered by existing state-of-the-art broadband diffractive imaging frameworks. This advancement eliminates the necessity for prior knowledge of probe spectrum and relaxes constraints on non-dispersive samples, resulting in a significant extension in spectral bandwidth, achieving a nearly fourfold improvement in bandlimit compared to the existing benchmark1.Â
In a recent development, we introduced a ultra-streamlined diffraction-based computational spectrometer based on the coherent mode decomposition from broadband diffraction measurement2. The implementation within the context of broadband computational imaging marks a significant advancement in recovering the compressive sampled profile of spectrum (CSS) of the imaging system. Drawing inspiration from the mono CDI framework3, we further propose an advancement to broaden the scope of CDI to ultra-broadband illumination with unknown probe spectrum, termed ultra-broadband diffractive imaging (UDI). UDI eliminates the need for prior knowledge of probe spectrum and relaxes constraints on non-dispersive samples, achieving significant enhancement in photon efficiency for ultra-broadband computational imaging. UDI not only reconstructs the CSS of the diffracted radiation, but also achieves a coherence-enhanced and superfast-solving monochromatization (CSM) of the captured broadband pattern with high efficiency.
The superiority of UDI is experimentally confirmed using both CDI and ptychography from an ultra-broadband spectrum with relative bandwidth exceeding 40%, revealing a precise spectrum measurement and a super-fast and robust monochromatization convergence with no need for prior spectral knowledge. This is particularly advantageous for in-line broadband imaging applications where efficiency and speed are crucial. To the best of our knowledge, this is the first demonstration of an ultra-broadband CDI comprising an ultra-simplified design, while eliminating the constraint of non-dispersion for the specimen or the need for accurate knowledge of probe spectrum, providing a successful ultra-broadband CDI with a significant improvement in photon utilization efficiency and remarkable enhancement in coherence across the entire spectrum.
Authors: Chuangchuang Chen, Honggang Gu, Shiyuan Liu.
References
[1] C. Chen, H. Gu, and S. Liu, “Ultra-broadband diffractive imaging with unknown probe spectrum,” Light Sci. Appl. 13, 213 (2024). https://doi.org/10.1038/s41377-024-01581-4
[2] C. Chen, H. Gu, and S. Liu, “Ultra-simplified diffraction-based computational spectrometer,” Light Sci. Appl. 13, 9 (2024). https://doi.org/10.1038/s41377-023-01355-4
[3] J. Huijts, S. Fernandez, D. Gauthier, M. Kholodtsova, A. Maghraoui, K. Medjoubi, A. Somogyi, W. Boutu, and H. Merdji, “Broadband coherent diffractive imaging,” Nat. Photonics 14, 618–622 (2020). https://doi.org/10.1038/s41566-020-0660-7