Polychromatic near-field ptychography

Near-field X-ray ptychography has recently been experimentally shown to be able to recover a sample's complex valued transmission function from multiple near-field diffraction images, each with a lateral shift of the sample, in the monochromatic (single energy) case. In this paper, we show via numerical simulation that near-field X-ray ptychography is feasible with a polychromatic X-ray beam. Specifically, with increasing the bandwidth of the energy spectrum, we observe a mild reduction in the visibility of the near-field speckles, and consequently an increase in the reconstruction error of the sample.