Enhancing Monochromatization for Broadband Coherent Diffractive Imaging

The stringent requirement for spectral coherence in coherent diffractive imaging has limited its broader application in achieving efficient photon utilization for broadband illumination, as ultrafast short light pulses have wide spectral bandwidth and, therefore, reduced temporal coherence. This paper proposes a further improved numerical monochromatization method to enhance the coherence of the broadband diffraction under wide band incoherent illumination by monochromatizating the polychromatic incoherent diffraction patterns. This superiority is achieved through an optimized coherence-enhanced, fast-solving, and noise-robust monochromatization (CFNM) method, which is experimentally verified using ptychography under wide spectral illumination with a relative bandwidth exceeding 40% FWHM. The experimental validations indicates that the proposed CFNM reveals a substantial boost in coherence and significantly enhanced imaging resolution with high fidelity under ultra-broadband illumination.