Fig. 1: Principle of ultra-broadband ptychography.

The broadband source passes through a phase-type structured aperture, forming a structured probe on the sample for two-dimensional scanning. Then, the transmitted wave propagates through free space to the detector plane, where the broadband far-field diffraction pattern dataset is recorded. The broadband diffraction intensity can be expressed in the form of a convolution between the coherent diffraction intensity and the kernel containing coherence information.