An improved ptychographical phase retrieval algorithm for diffractive imaging

Maiden, Andrew; Rodenburg, J. M.

doi:10.1016/j.ultramic.2009.05.012

Cited by 1,274 publications

(1,001 citation statements)

References 19 publications

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“…The incident X-ray probe is recovered simultaneously by the extended ptychographical iterative engine (ePIE) reconstruction 3 and is shown in Fig. 4a, where brightness represents the amplitude and hue represents the phase.…”

Section: Resultsmentioning

confidence: 99%

“…The technique involves successively illuminating overlapping regions of a specimen with a localized probe and recording the resulting diffraction patterns. A key requirement is that the illuminated areas overlap substantially, so that iterative algorithms [1][2][3] can successfully reconstruct an image of the specimen, retrieving the amplitude and phase of both the complex sample transmission function and the illuminating probe. At X-ray wavelengths, ptychography has been used to characterize the focusing properties of X-ray optics [4][5][6] , to image interconnects within microchips 7 and to image yeast cells 8 .…”

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confidence: 99%

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Soft X-ray spectromicroscopy using ptychography with randomly phased illumination

et al. 2013

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Ptychography is a form of scanning diffractive imaging that can successfully retrieve the modulus and phase of both the sample transmission function and the illuminating probe. An experimental difficulty commonly encountered in diffractive imaging is the large dynamic range of the diffraction data. Here we report a novel ptychographic experiment using a randomly phased X-ray probe to considerably reduce the dynamic range of the recorded diffraction patterns. Images can be reconstructed reliably and robustly from this setup, even when scatter from the specimen is weak. A series of ptychographic reconstructions at X-ray energies around the L absorption edge of iron demonstrates the advantages of this method for soft X-ray spectromicroscopy, which can readily provide chemical sensitivity without the need for optical refocusing. In particular, the phase signal is in perfect registration with the modulus signal and provides complementary information that can be more sensitive to changes in the local chemical environment.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Soft X-ray spectromicroscopy using ptychography with randomly phased illumination

et al. 2013

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“…Constructive algorithms exist for ptychography from weakly scattering objects, which have been shown to constitute an optimally electron-efficient processing of 4D data [7,9]. For strong phase objects, ptychography tends to involve iterative approaches [36][37][38]. In principle, one of the strengths of ptychography is super-resolution: iterative ptychography is not bandwidth limited by the probe-forming lens.…”

Section: Phase Reconstruction From Dpc Imagesmentioning

confidence: 99%

Practical aspects of diffractive imaging using an atomic-scale coherent electron probe

et al. 2016

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a b s t r a c tFour-dimensional scanning transmission electron microscopy (4D-STEM) is a technique where a full twodimensional convergent beam electron diffraction (CBED) pattern is acquired at every STEM pixel scanned. Capturing the full diffraction pattern provides a rich dataset that potentially contains more information about the specimen than is contained in conventional imaging modes using conventional integrating detectors. Using 4D datasets in STEM from two specimens, monolayer MoS 2 and bulk SrTiO 3 , we demonstrate multiple STEM imaging modes on a quantitative absolute intensity scale, including phase reconstruction of the transmission function via differential phase contrast imaging. Practical issues about sampling (i.e. number of detector pixels), signal-to-noise enhancement and data reduction of large 4D-STEM datasets are emphasized.

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“…These patterns are combined with a phase retrieval algorithm to reconstruct the complex profiles of the object and probe beam. Ptychography provides excellent image fidelity compared to other techniques such as scanning electron microscope (SEM) imaging [1,3,6], requires no contact with the sample, has a working distance of centimeters and does not suffer from adverse effects such as surface charging.We used an actively stabilized 13.5nm HHG source (KM Labs XUUS 4.0) driven by a 20fs, 2mJ, 3kHz, Ti:Sapphire laser centered at 785nm (KM Labs Dragon), and generated a flux which was 10 times higher than was previously possible using the same driving laser [2]. The HHG light was produced in a 150µm diameter waveguide filled with 500 Torr of He.…”

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confidence: 99%

“…Tabletop EUV CDI combines elemental and chemical selectivity with nanometer spatial resolution, with pulse durations in the femtosecond (fs)-toattosecond (as) range [1][2][3][4][5]. In this work, we use ptychographic CDI [6][7] with high-spatial-coherence 13.5nm tabletop HHG to obtain 17.5nm spatial resolution images of a zone plate. This is the highest demonstrated resolution for a full-field tabletop microscope using any light source.…”

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Coherent Ptychographic Imaging Microscope With 17.5nm Spatial Resolution Employing 13.5nm High Harmonic Light

et al. 2016

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High-resolution imaging is an essential tool for understanding nanoscale systems. In particular, tabletop extreme ultraviolet (EUV) coherent diffractive imaging (CDI) techniques based on high harmonic generation (HHG) are ideal for investigating complex nanostructured systems, including their static and dynamic electronic, phononic and magnetic properties. Tabletop EUV CDI combines elemental and chemical selectivity with nanometer spatial resolution, with pulse durations in the femtosecond (fs)-toattosecond (as) range [1][2][3][4][5]. In this work, we use ptychographic CDI [6][7] with high-spatial-coherence 13.5nm tabletop HHG to obtain 17.5nm spatial resolution images of a zone plate. This is the highest demonstrated resolution for a full-field tabletop microscope using any light source.In CDI, also known as lensless imaging, a coherent beam illuminates an object and the diffracted light is directly recorded on a charge-coupled device (CCD) far from the sample. The phase profile of the diffraction pattern, lost by the detector, is recovered computationally, and the object is reconstructed by numerically back-propagating this field [8]. In a newly-developed form of CDI called ptychography, many diffraction patterns are recorded as an illuminating beam is scanned across a sample. These patterns are combined with a phase retrieval algorithm to reconstruct the complex profiles of the object and probe beam. Ptychography provides excellent image fidelity compared to other techniques such as scanning electron microscope (SEM) imaging [1,3,6], requires no contact with the sample, has a working distance of centimeters and does not suffer from adverse effects such as surface charging.We used an actively stabilized 13.5nm HHG source (KM Labs XUUS 4.0) driven by a 20fs, 2mJ, 3kHz, Ti:Sapphire laser centered at 785nm (KM Labs Dragon), and generated a flux which was 10 times higher than was previously possible using the same driving laser [2]. The HHG light was produced in a 150µm diameter waveguide filled with 500 Torr of He. Differential pumping helped maintain high vacuum before and after the waveguide. After the waveguide, the residual IR light was attenuated using a pair of ZrO 2 coated Si mirrors placed near Brewster's angle, together with a single 600nm thick Zr foil filter. A single harmonic was then selected using a pair of Si/Mo multilayer mirrors.The imaging setup is depicted in Fig. 1a. A flat mirror is followed by a curved mirror (radius of curvature 100mm), which focuses the beam onto the sample. The angle of incidence on the curved mirror is approximately 2.5°, resulting in a 2.7µm 1/e 2 diameter at the circle of least confusion. Diffraction from a zone plate test sample was collected by a CCD detector (Andor iKon, 2048x2048 pixels, 13.5µm pitch) placed 22.6mm from the sample. This geometry provided a numerical aperture (NA) of 0.4, corresponding to a half-pitch resolution of 17.5nm. The beam was scanned in an 11x11 grid with ≈0.8µm steps, with a total exposure time (121 diffraction patterns, two accumulations...

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An improved ptychographical phase retrieval algorithm for diffractive imaging

Cited by 1,274 publications

References 19 publications

Soft X-ray spectromicroscopy using ptychography with randomly phased illumination

Soft X-ray spectromicroscopy using ptychography with randomly phased illumination

Practical aspects of diffractive imaging using an atomic-scale coherent electron probe

Coherent Ptychographic Imaging Microscope With 17.5nm Spatial Resolution Employing 13.5nm High Harmonic Light

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