Probe retrieval in ptychographic coherent diffractive imaging

Quantitative Chemically Specific Coherent Diffractive Imaging of Reactions at Buried Interfaces with Few Nanometer Precision

“…For both samples, the ptychographic data set consisted of 270 diffraction patterns, collected with 3 µm step sizes between scan positions. A random offset of ±20% of the step size was added to each scan position to prevent periodic artifacts in the reconstructions [32]. The total EUV exposure time for the uncoated sample was 5.8 min, compared with 23.6 min for the Al-coated sample, with a total scanned area of 4270 µm 2 each.…”

Coherent X-ray diffractive imaging on the single-cell-level of microbial samples

“…More recent ptychographic studies investigate the maximum derivable information from ptychographic data under non-simple experimental conditions for the illuminating wave-eld or the object such as position uncertainties [20,110,182], partial coherence and multiple wavelenghts [15,44,78,299], multiple object planes [181,284] and undersampling of the recorded di racted intensities [71]. In the rst place, however, the probably most important result has been the understanding that the ptychographic method not only is able to solve for the encoded object information but also for the illuminating wave-eld [183,294,296] making ptychography a valuable tool for analysing the wave-elds of X-rays [134,144,159,160,265,268]. In principle, the decoupling of object and illuminating wave-eld makes the retrieved object information free of aberrations.…”

“…In case of the DM algorithm [294], the probe update appears to be practically carried out only once after cycling through all positions. For this reason, the ePIE update of the object may often be more advantageous than the update of the DM ptychographic algorithm.…”

“…Next, details about the algorithmic and experimental parameters are listed. Here, two di erent ptychographic algorithms were used:`DM' (di erence-map) [294] (and references therein) and`ePIE' [183] (see also section 1.3.6, p. 40). Following the strategy of [62], a Siemens star resolution test chart (model ATN/ XRESO-50HC, NTT-AT, Japan) was used in order to get a good estimate of the probe, which could be used as an initial guess for the phasing of the bacterial specimens.…”

“…It originates from the eld of electron microscopy [136,138,139,210]. The great power of the ptychographic method is its capability to simultaneously reconstruct not only information about the probed object but also about the illuminating wave-eld which typically is denoted as the probe [183,294,296]. In principle, the capability to separate the illuminating wave-eld from the object makes the retrieved object information free of aberrations.…”