Physics and Astronomy › Radiation

Advanced X-ray Imaging Techniques

Works Count: 40639

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Description

This cluster of papers focuses on advanced X-ray imaging techniques and applications, including phase retrieval, tomography, ptychography, coherent diffractive imaging, nanoscale imaging, soft X-ray microscopy, and phase contrast imaging. The papers cover a wide range of topics such as femtosecond X-ray pulses, high-resolution imaging, and the use of novel algorithms for image reconstruction.

Keywords

X-ray Imaging; Phase Retrieval; Tomography; Ptychography; Coherent Diffractive Imaging; Nanoscale Imaging; Soft X-ray Microscopy; Diffraction Microscopy; Phase Contrast Imaging; Femtosecond X-ray Pulses

X-Rays in Theory and Experiment

1935-01-01

Arthur Holly Compton , S Allison

Potential for biomolecular imaging with femtosecond X-ray pulses

2000-08-17

Richard Neutze , R. Wouts , David van der Spoel +2 more

Extending the methodology of X-ray crystallography to allow imaging of micrometre-sized non-crystalline specimens

1999-07-01

Jianwei Miao , Pambos Charalambous , Janos Kirz +1 more

Simultaneous phase and amplitude extraction from a single defocused image of a homogeneous object

2002-04-01

David M. Paganin , S. C. Mayo , Timur E. Gureyev +2 more

We demonstrate simultaneous phase and amplitude extraction from a single defocused image of a homogeneous object. Subject to the assumptions explicitly stated in the derivation, the algorithm solves the twin-image … We demonstrate simultaneous phase and amplitude extraction from a single defocused image of a homogeneous object. Subject to the assumptions explicitly stated in the derivation, the algorithm solves the twin-image problem of in-line holography and is capable of analysing data obtained using X-ray microscopy, electron microscopy, neutron microscopy or visible-light microscopy, especially as they relate to defocus and point projection methods. Our simple, robust, non-iterative and computationally efficient method is applied to data obtained using an X-ray phase contrast ultramicroscope.

Reconstruction of an object from the modulus of its Fourier transform

1978-07-01

James R. Fienup

We present a digital method for solving the phase-retrieval problem of optical-coherence theory: the reconstruction of a general object from the modulus of its Fourier transform. This technique should be … We present a digital method for solving the phase-retrieval problem of optical-coherence theory: the reconstruction of a general object from the modulus of its Fourier transform. This technique should be useful for obtaining high-resolution imagery from interferometer data.

Noninterferometric Phase Imaging with Partially Coherent Light

1998-03-23

David M. Paganin , K. Nugent

We demonstrate that interferometric imaging may be replaced by noninterferometric propagation-based techniques in many experiments. We explore propagation through the Poynting vector and find two classes of phase, one of … We demonstrate that interferometric imaging may be replaced by noninterferometric propagation-based techniques in many experiments. We explore propagation through the Poynting vector and find two classes of phase, one of which is topological in origin. Only this latter class may require interferometry to be determined, and even then only in specific well-defined circumstances. Our alternative definitions of phase are readily generalized to partially coherent radiation. Our analysis leads to an approach that is able to determine the absolute phase and the amplitude of a wave.

First lasing and operation of an ångstrom-wavelength free-electron laser

2010-08-01

P. Emma , R. Akre , John Arthur +7 more

Operation of a free-electron laser from the extreme ultraviolet to the water window

2007-06-01

W. Ackermann , G. Asova , V. Ayvazyan +7 more

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Phase-contrast imaging of weakly absorbing materials using hard X-rays

1995-02-01

Timothy J. Davis , D. Gao , Timur E. Gureyev +2 more

A phase retrieval algorithm for shifting illumination

2004-11-15

J. M. Rodenburg , H. M. L. Faulkner

We propose a method of iterative phase retrieval that uses measured intensities in the diffraction plane to solve the phase problem in a way that bypasses the problem of lens … We propose a method of iterative phase retrieval that uses measured intensities in the diffraction plane to solve the phase problem in a way that bypasses the problem of lens aberration, leading to greatly improved spatial resolution. This method is stable, easy to implement experimentally, and can be used to view a large area of the specimen when that is desired.

Demonstration of X-Ray Talbot Interferometry

2003-07-15

Atsushi Momose , Shinya Kawamoto , Ichiro Koyama +3 more

First Talbot interferometry in the hard X-ray region was demonstrated using a pair of transmission gratings made by forming gold stripes on glass plates. By aligning the gratings on the … First Talbot interferometry in the hard X-ray region was demonstrated using a pair of transmission gratings made by forming gold stripes on glass plates. By aligning the gratings on the optical axis of X-rays with a separation that caused the Talbot effect by the first grating, moiré fringes were produced inclining one grating slightly against the other around the optical axis. A phase object placed in front of the first grating was detected by moiré-fringe bending. Using the technique of phase-shifting interferometry, the differential phase corresponding to the phase object could also be measured. This result suggests that X-ray Talbot interferometry is a novel and simple method for phase-sensitive X-ray radiography.

Phase-contrast imaging using polychromatic hard X-rays

1996-11-01

S. Wilkins , Timur E. Gureyev , D. Gao +2 more

Femtosecond X-ray protein nanocrystallography

2011-02-01

Henry N. Chapman , Petra Fromme , Anton Barty +7 more

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X-ray image reconstruction from a diffraction pattern alone

2003-10-28

Stefano Marchesini , Haifeng He , Henry N. Chapman +5 more

A solution to the inversion problem of scattering would offer aberration-free diffraction-limited three-dimensional images without the resolution and depth-of-field limitations of lens-based tomographic systems. Powerful algorithms are increasingly being used … A solution to the inversion problem of scattering would offer aberration-free diffraction-limited three-dimensional images without the resolution and depth-of-field limitations of lens-based tomographic systems. Powerful algorithms are increasingly being used to act as lenses to form such images. Current image reconstruction methods, however, require the knowledge of the shape of the object and the low spatial frequencies unavoidably lost in experiments. Diffractive imaging has thus previously been used to increase the resolution of images obtained by other means. Here we experimentally demonstrate an inversion method, which reconstructs the image of the object without the need for any such prior knowledge.

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Phase retrieval algorithms: a comparison

1982-08-01

James R. Fienup

Iterative algorithms for phase retrieval from intensity data are compared to gradient search methods. Both the problem of phase retrieval from two intensity measurements (in electron microscopy or wave front … Iterative algorithms for phase retrieval from intensity data are compared to gradient search methods. Both the problem of phase retrieval from two intensity measurements (in electron microscopy or wave front sensing) and the problem of phase retrieval from a single intensity measurement plus a non-negativity constraint (in astronomy) are considered, with emphasis on the latter. It is shown that both the error-reduction algorithm for the problem of a single intensity measurement and the Gerchberg-Saxton algorithm for the problem of two intensity measurements converge. The error-reduction algorithm is also shown to be closely related to the steepest-descent method. Other algorithms, including the input-output algorithm and the conjugate-gradient method, are shown to converge in practice much faster than the error-reduction algorithm. Examples are shown.

High-Resolution Scanning X-ray Diffraction Microscopy

2008-07-17

Pierre Thibault , Martin Dierolf , Andreas Menzel +3 more

Coherent diffractive imaging (CDI) and scanning transmission x-ray microscopy (STXM) are two popular microscopy techniques that have evolved quite independently. CDI promises to reach resolutions below 10 nanometers, but the … Coherent diffractive imaging (CDI) and scanning transmission x-ray microscopy (STXM) are two popular microscopy techniques that have evolved quite independently. CDI promises to reach resolutions below 10 nanometers, but the reconstruction procedures put stringent requirements on data quality and sample preparation. In contrast, STXM features straightforward data analysis, but its resolution is limited by the spot size on the specimen. We demonstrate a ptychographic imaging method that bridges the gap between CDI and STXM by measuring complete diffraction patterns at each point of a STXM scan. The high penetration power of x-rays in combination with the high spatial resolution will allow investigation of a wide range of complex mesoscopic life and material science specimens, such as embedded semiconductor devices or cellular networks.

Reconstruction of Abel-transformable images: The Gaussian basis-set expansion Abel transform method

2002-07-01

V. Dribinski , Alexei Ossadtchi , Vladimir A. Mandelshtam +1 more

In this article we present a new method for reconstructing three-dimensional (3D) images with cylindrical symmetry from their two-dimensional projections. The method is based on expanding the projection in a … In this article we present a new method for reconstructing three-dimensional (3D) images with cylindrical symmetry from their two-dimensional projections. The method is based on expanding the projection in a basis set of functions that are analytical projections of known well-behaved functions. The original 3D image can then be reconstructed as a linear combination of these well-behaved functions, which have a Gaussian-like shape, with the same expansion coefficients as the projection. In the process of finding the expansion coefficients, regularization is used to achieve a more reliable reconstruction of noisy projections. The method is efficient and computationally cheap and is particularly well suited for transforming projections obtained in photoion and photoelectron imaging experiments. It can be used for any image with cylindrical symmetry, requires minimal user’s input, and provides a reliable reconstruction in certain cases when the commonly used Fourier–Hankel Abel transform method fails.

Phase Retrieval with Application to Optical Imaging: A contemporary overview

2015-04-03

Yoav Shechtman , Yonina C. Eldar , Oren Cohen +3 more

The problem of phase retrieval, i.e., the recovery of a function given the magnitude of its Fourier transform, arises in various fields of science and engineering, including electron microscopy, crystallography, … The problem of phase retrieval, i.e., the recovery of a function given the magnitude of its Fourier transform, arises in various fields of science and engineering, including electron microscopy, crystallography, astronomy, and optical imaging. Exploring phase retrieval in optical settings, specifically when the light originates from a laser, is natural since optical detection devices [e.g., charge-coupled device (CCD) cameras, photosensitive films, and the human eye] cannot measure the phase of a light wave. This is because, generally, optical measurement devices that rely on converting photons to electrons (current) do not allow for direct recording of the phase: the electromagnetic field oscillates at rates of ~1015 Hz, which no electronic measurement device can follow. Indeed, optical measurement/detection systems measure the photon flux, which is proportional to the magnitude squared of the field, not the phase. Consequently, measuring the phase of optical waves (electromagnetic fields oscillating at 1015 Hz and higher) involves additional complexity, typically by requiring interference with another known field, in the process of holography.

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Deterministic phase retrieval: a Green’s function solution

1983-11-01

M. R. Teague

Equations for the propagation of phase and irradiance are derived, and a Green's function solution for the phase in terms of irradiance and perimeter phase values is given. A measurement … Equations for the propagation of phase and irradiance are derived, and a Green's function solution for the phase in terms of irradiance and perimeter phase values is given. A measurement scheme is discussed, and the results of a numerical simulation are given. Both circular and slit pupils are considered. An appendix discusses the local validity of the parabolic-wave equation based on the factorized Helmholtz equation approach to the Rayleigh–Sommerfeld and Fresnel diffraction theories. Expressions for the diffracted-wave field in the near-field region are given.

Holotomography: Quantitative phase tomography with micrometer resolution using hard synchrotron radiation x rays

1999-11-08

Peter Cloetens , Wolfgang Ludwig , J. Baruchel +4 more

Because the refractive index for hard x rays is slightly different from unity, the optical phase of a beam is affected by transmission through an object. Phase images can be … Because the refractive index for hard x rays is slightly different from unity, the optical phase of a beam is affected by transmission through an object. Phase images can be obtained with extreme instrumental simplicity by simple propagation provided the beam is coherent. But, unlike absorption, the phase is not simply related to image brightness. A holographic reconstruction procedure combining images taken at different distances from the specimen was developed. It results in quantitative phase mapping and, through association with three-dimensional reconstruction, in holotomography, the complete three-dimensional mapping of the density in a sample. This tool in the characterization of materials at the micrometer scale is uniquely suited to samples with low absorption contrast and radiation-sensitive systems.

Movable Aperture Lensless Transmission Microscopy: A Novel Phase Retrieval Algorithm

2004-07-09

H. M. L. Faulkner , J. M. Rodenburg

We propose an iterative phase retrieval method that uses a series of diffraction patterns, measured only in intensity, to solve for both amplitude and phase of the image wave function … We propose an iterative phase retrieval method that uses a series of diffraction patterns, measured only in intensity, to solve for both amplitude and phase of the image wave function over a wide field of view and at wavelength-limited resolution. The new technique requires an aperture that is scanned to two or more positions over the object wave function. A simple implementation of the method is modeled and demonstrated, showing how the algorithm uses overlapping data in real space to resolve ambiguities in the solution. The technique opens up the possibility of practical transmission lensless microscopy at subatomic resolution using electrons, x rays, or nuclear particles.

Ptychographic X-ray computed tomography at the nanoscale

2010-09-01

Martin Dierolf , Andreas Menzel , Pierre Thibault +5 more

Phase objects in synchrotron radiation hard x-ray imaging

1996-01-14

Peter Cloetens , R. Barrett , J. Baruchel +2 more

Phase objects are readily imaged through Fresnel diffraction in the hard x-ray beams of third-generation synchrotron radiation sources such as the ESRF, due essentially to the very small angular size … Phase objects are readily imaged through Fresnel diffraction in the hard x-ray beams of third-generation synchrotron radiation sources such as the ESRF, due essentially to the very small angular size of the source. Phase objects can lead to spurious contrast in x-ray diffraction images (topographs) of crystals. It is shown that this contrast can be eliminated through random phase plates, which provide an effective way of tailoring the angular size of the source. The possibilities of this very simple technique for imaging phase objects in the hard x-ray range are explored experimentally and discussed. They appear very promising, as shown in particular by the example of a piece of human vertebra, and could be extended to phase tomography.

An experimental investigation of extrapolation methods in the derivation of accurate unit-cell dimensions of crystals

1945-05-01

James B. Nelson , Daniel P. Riley

Measurements on X-ray photographs of cylindrical specimens of different absorption and thickness taken in a camera without eccentricity show that the absorption error in the apparent unit-cell dimension a is … Measurements on X-ray photographs of cylindrical specimens of different absorption and thickness taken in a camera without eccentricity show that the absorption error in the apparent unit-cell dimension a is proportional to cos2θ/sinθ + cos2θ/θ. The plot of a against ½(cos2θ/sinθ + cos2θ/θ) is linear down to θ = 30° for all four specimens used. The extrapolated values for a are in good agreement, and this extrapolation function is accordingly recommended in the case of data from well constructed cameras. Other extrapolation functions are also considered, and the effect of various sources of error discussed. A table of ½(cos2θ/sinθ + cos2θ/θ) is given.

Phase retrieval in crystallography and optics

1990-03-01

Rick P. Millane

Phase problems occur in many scientific disciplines, particularly those involving remote sensing using a wave field. Although there has been much interest in phase retrieval in optics and in imaging … Phase problems occur in many scientific disciplines, particularly those involving remote sensing using a wave field. Although there has been much interest in phase retrieval in optics and in imaging in general over the past decade, phase retrieval has a much longer history in x-ray crystallography, and a variety of powerful and practical techniques have been developed. The nature of crystallography means that crystallographic phase problems are distinct from those in other imaging contexts, but there are a number of commonalities. Here the principles of phase retrieval in crystallography are outlined and are compared and contrasted with phase retrieval in general imaging. Uniqueness results are discussed, but the emphasis is on phase-retrieval algorithms and areas in which results in one discipline have, and may, contribute to the other.

Wide-field, high-resolution Fourier ptychographic microscopy

2013-07-26

Guoan Zheng , Roarke Horstmeyer , Changhuei Yang

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Femtosecond electronic response of atoms to ultra-intense X-rays

2010-06-29

Linda Young , E. P. Kanter , B. Krässig +7 more

Diffraction enhanced x-ray imaging

1997-11-01

D. Chapman , W. Thomlinson , Richard Johnston +7 more

Diffraction enhanced imaging is a new x-ray radiographic imaging modality using monochromatic x-rays from a synchrotron which produces images of thick absorbing objects that are almost completely free of scatter. … Diffraction enhanced imaging is a new x-ray radiographic imaging modality using monochromatic x-rays from a synchrotron which produces images of thick absorbing objects that are almost completely free of scatter. They show dramatically improved contrast over standard imaging applied to the same phantom. The contrast is based not only on attenuation but also the refraction and diffraction properties of the sample. This imaging method may improve image quality for medical applications, industrial radiography for non-destructive testing and x-ray computed tomography.

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Phase retrieval and differential phase-contrast imaging with low-brilliance X-ray sources

2006-03-26

Franz Pfeiffer , Timm Weitkamp , Oliver Bunk +1 more

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X-ray free-electron lasers

2010-11-30

Brian McNeil , Neil Thompson

Phase retrieval by iterated projections

2003-01-01

Veit Elser

Several strategies in phase retrieval are unified by an iterative "difference map" constructed from a pair of elementary projections and three real parameters. For the standard application in optics, where … Several strategies in phase retrieval are unified by an iterative "difference map" constructed from a pair of elementary projections and three real parameters. For the standard application in optics, where the two projections implement Fourier modulus and object support constraints, respectively, the difference map reproduces the "hybrid" form of Fienup's input-output map when a particular choice is made for two of the parameters. The geometric construction of the difference map illuminates the distinction between its fixed points and the recovered object, as well as the mechanism whereby the form of stagnation encountered by alternating projection schemes is avoided. When support constraints are replaced by object histogram or atomicity constraints, the difference map lends itself to crystallographic phase retrieval. Numerical experiments with synthetic data suggest that structures with hundreds of atoms can be solved.

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Soft X-ray microscopy at a spatial resolution better than 15 nm

2005-06-01

Weilun Chao , B. Harteneck , J. Alexander Liddle +2 more

On the possibilities of x-ray phase contrast microimaging by coherent high-energy synchrotron radiation

1995-12-01

A. Snigirev , I. Snigireva , V. G. Kohn +2 more

Coherent properties of the x-ray beam delivered at the ESRF allow the observation of very weak perturbations of the wave front, resulting in the phase contrast. A straightforward experimental setup … Coherent properties of the x-ray beam delivered at the ESRF allow the observation of very weak perturbations of the wave front, resulting in the phase contrast. A straightforward experimental setup for phase contrast imaging is proposed and used to record holographic images from organic samples of 10–100 μm at energy 10–50 keV with the contrast up to 50%–100%. The theory of phase contrast imaging is considered and some theoretical estimations are made to reveal the performance of the proposed technique in terms of resolution, sensitivity, geometrical requirements, and energy range applicability. It is found that for carbon-based fibers a detectable size with 2% contrast is 0.1 μm for 10 keV and −1 μm for 100 keV. It is demonstrated that the fine interference structure of the image is very sensitive to the shape, density variation, and internal structure of the sample. Some prospects for the practical use and future development of the new coherent techniques such as phase contrast microscopy, microtomography, holography, and interferometry at high energies are also discussed.

Hard-X-Ray Lensless Imaging of Extended Objects

2007-01-18

J. M. Rodenburg , A C Hurst , A. G. Cullis +6 more

We demonstrate a hard-x-ray microscope that does not use a lens and is not limited to a small field of view or an object of finite size. The method does … We demonstrate a hard-x-ray microscope that does not use a lens and is not limited to a small field of view or an object of finite size. The method does not suffer any of the physical constraints, convergence problems, or defocus ambiguities that often arise in conventional phase-retrieval diffractive imaging techniques. Calculation times are about a thousand times shorter than in current iterative algorithms. We need no a priori knowledge about the object, which can be a transmission function with both modulus and phase components. The technique has revolutionary implications for x-ray imaging of all classes of specimen.

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Beyond crystallography: Diffractive imaging using coherent x-ray light sources

2015-04-30

Jianwei Miao , Tetsuya Ishikawa , Ian Robinson +1 more

X-ray crystallography has been central to the development of many fields of science over the past century. It has now matured to a point that as long as good-quality crystals … X-ray crystallography has been central to the development of many fields of science over the past century. It has now matured to a point that as long as good-quality crystals are available, their atomic structure can be routinely determined in three dimensions. However, many samples in physics, chemistry, materials science, nanoscience, geology, and biology are noncrystalline, and thus their three-dimensional structures are not accessible by traditional x-ray crystallography. Overcoming this hurdle has required the development of new coherent imaging methods to harness new coherent x-ray light sources. Here we review the revolutionary advances that are transforming x-ray sources and imaging in the 21st century.

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PhaseLift: Exact and Stable Signal Recovery from Magnitude Measurements via Convex Programming

2012-11-14

Emmanuel J. Candès , Thomas Strohmer , Vladislav Voroninski

Abstract Suppose we wish to recover a signal \input amssym $\font\abc=cmmib10\def\bi#1{\hbox{\abc#1}} {\bi x} \in {\Bbb C}^n$ from m intensity measurements of the form $\font\abc=cmmib10\def\bi#1{\hbox{\abc#1}} |\langle \bi x,\bi z_i \rangle|^2$ , … Abstract Suppose we wish to recover a signal \input amssym $\font\abc=cmmib10\def\bi#1{\hbox{\abc#1}} {\bi x} \in {\Bbb C}^n$ from m intensity measurements of the form $\font\abc=cmmib10\def\bi#1{\hbox{\abc#1}} |\langle \bi x,\bi z_i \rangle|^2$ , $i = 1, 2, \ldots, m$ ; that is, from data in which phase information is missing. We prove that if the vectors $\font\abc=cmmib10\def\bi#1{\hbox{\abc#1}}{\bi z}_i$ are sampled independently and uniformly at random on the unit sphere, then the signal x can be recovered exactly (up to a global phase factor) by solving a convenient semidefinite program–‐a trace‐norm minimization problem; this holds with large probability provided that m is on the order of $n {\log n}$ , and without any assumption about the signal whatsoever. This novel result demonstrates that in some instances, the combinatorial phase retrieval problem can be solved by convex programming techniques. Finally, we also prove that our methodology is robust vis‐à‐vis additive noise. © 2012 Wiley Periodicals, Inc.

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A compact X-ray free-electron laser emitting in the sub-ångström region

2012-06-22

Tetsuya Ishikawa , H. Aoyagi , T. Asaka +7 more

Phase–contrast X–ray computed tomography for observing biological soft tissues

1996-04-01

Atsushi Momose , Tohoru Takeda , Yuji Itai +1 more

A compound refractive lens for focusing high-energy X-rays

1996-11-01

A. Snigirev , V. G. Kohn , I. Snigireva +1 more

X-ray phase imaging with a grating interferometer

2005-08-08

Timm Weitkamp , Ana Díaz , Christian Dávid +4 more

Using a high-efficiency grating interferometer for hard X rays (10–30 keV) and a phase-stepping technique, separate radiographs of the phase and absorption profiles of bulk samples can be obtained from … Using a high-efficiency grating interferometer for hard X rays (10–30 keV) and a phase-stepping technique, separate radiographs of the phase and absorption profiles of bulk samples can be obtained from a single set of measurements. Tomographic reconstruction yields quantitative three-dimensional maps of the X-ray refractive index, with a spatial resolution down to a few microns. The method is mechanically robust, requires little spatial coherence and monochromaticity, and can be scaled up to large fields of view, with a detector of correspondingly moderate spatial resolution. These are important prerequisites for use with laboratory X-ray sources.

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X-ray phase-contrast imaging: from pre-clinical applications towards clinics

2012-12-10

Alberto Bravin , Paola Coan , P. Suortti

Phase-contrast x-ray imaging (PCI) is an innovative method that is sensitive to the refraction of the x-rays in matter. PCI is particularly adapted to visualize weakly absorbing details like those … Phase-contrast x-ray imaging (PCI) is an innovative method that is sensitive to the refraction of the x-rays in matter. PCI is particularly adapted to visualize weakly absorbing details like those often encountered in biology and medicine. In past years, PCI has become one of the most used imaging methods in laboratory and preclinical studies: its unique characteristics allow high contrast 3D visualization of thick and complex samples even at high spatial resolution. Applications have covered a wide range of pathologies and organs, and are more and more often performed in vivo. Several techniques are now available to exploit and visualize the phase-contrast: propagation- and analyzer-based, crystal and grating interferometry and non-interferometric methods like the coded aperture. In this review, covering the last five years, we will give an overview of the main theoretical and experimental developments and of the important steps performed towards the clinical implementation of PCI.

Hard-X-ray dark-field imaging using a grating interferometer

2008-01-20

Franz Pfeiffer , Martin Bech , Oliver Bunk +5 more

Formation of Optical Images by X-Rays

1948-09-01

Paul Kirkpatrick , Albert V. Baez

Several conceivable methods for the formation of optical images by x-rays are considered, and a method employing concave mirrors is adopted as the most promising. A concave spherical mirror receiving … Several conceivable methods for the formation of optical images by x-rays are considered, and a method employing concave mirrors is adopted as the most promising. A concave spherical mirror receiving radiation at grazing incidence (a necessary arrangement with x-rays) images a point into a line in accordance with a focal length f=Ri/2 where R is the radius of curvature and i the grazing angle. The image is subject to an aberration such that a ray reflected at the periphery of the mirror misses the focal point of central rays by a distance given approximately by S=1.5Mr2/R, where M is the magnification of the image and r is the radius of the mirror face. The theoretically possible resolving power is such as to resolve point objects separated by about 70A, a limit which is independent of the wave-length used. Point images of points and therefore extended images of extended objects may be produced by causing the radiation to reflect from two concave mirrors in series. Sample results are presented.

Single mimivirus particles intercepted and imaged with an X-ray laser

2011-02-01

M. Seibert , Tomas Ekeberg , Filipe R. N. C. Maia +7 more

Femtosecond diffractive imaging with a soft-X-ray free-electron laser

2006-11-12

Henry N. Chapman , Anton Barty , Michael J. Bogan +7 more

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MicroCT for comparative morphology: simple staining methods allow high-contrast 3D imaging of diverse non-mineralized animal tissues

2009-01-01

Brian Metscher

Comparative, functional, and developmental studies of animal morphology require accurate visualization of three-dimensional structures, but few widely applicable methods exist for non-destructive whole-volume imaging of animal tissues. Quantitative studies in … Comparative, functional, and developmental studies of animal morphology require accurate visualization of three-dimensional structures, but few widely applicable methods exist for non-destructive whole-volume imaging of animal tissues. Quantitative studies in particular require accurately aligned and calibrated volume images of animal structures. X-ray microtomography (microCT) has the potential to produce quantitative 3D images of small biological samples, but its widespread use for non-mineralized tissues has been limited by the low x-ray contrast of soft tissues. Although osmium staining and a few other techniques have been used for contrast enhancement, generally useful methods for microCT imaging for comparative morphology are still lacking. Several very simple and versatile staining methods are presented for microCT imaging of animal soft tissues, along with advice on tissue fixation and sample preparation. The stains, based on inorganic iodine and phosphotungstic acid, are easier to handle and much less toxic than osmium, and they produce high-contrast x-ray images of a wide variety of soft tissues. The breadth of possible applications is illustrated with a few microCT images of model and non-model animals, including volume and section images of vertebrates, embryos, insects, and other invertebrates. Each image dataset contains x-ray absorbance values for every point in the imaged volume, and objects as small as individual muscle fibers and single blood cells can be resolved in their original locations and orientations within the sample. With very simple contrast staining, microCT imaging can produce quantitative, high-resolution, high-contrast volume images of animal soft tissues, without destroying the specimens and with possibilities of combining with other preparation and imaging methods. Such images are expected to be useful in comparative, developmental, functional, and quantitative studies of morphology.

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An improved ptychographical phase retrieval algorithm for diffractive imaging

2009-06-10

Andrew Maiden , J. M. Rodenburg

Systems and transforms with applications in optics

1969-10-01

Adolf W. Lohmann

Phase Retrieval via Wirtinger Flow: Theory and Algorithms

2015-02-03

Emmanuel J. Candès , Xiaodong Li , Mahdi Soltanolkotabi

We study the problem of recovering the phase from magnitude measurements; specifically, we wish to reconstruct a complex-valued signal x of C^n about which we have phaseless samples of the … We study the problem of recovering the phase from magnitude measurements; specifically, we wish to reconstruct a complex-valued signal x of C^n about which we have phaseless samples of the form y_r = |< a_r,x >|^2, r = 1,2,...,m (knowledge of the phase of these samples would yield a linear system). This paper develops a non-convex formulation of the phase retrieval problem as well as a concrete solution algorithm. In a nutshell, this algorithm starts with a careful initialization obtained by means of a spectral method, and then refines this initial estimate by iteratively applying novel update rules, which have low computational complexity, much like in a gradient descent scheme. The main contribution is that this algorithm is shown to rigorously allow the exact retrieval of phase information from a nearly minimal number of random measurements. Indeed, the sequence of successive iterates provably converges to the solution at a geometric rate so that the proposed scheme is efficient both in terms of computational and data resources. In theory, a variation on this scheme leads to a near-linear time algorithm for a physically realizable model based on coded diffraction patterns. We illustrate the effectiveness of our methods with various experiments on image data. Underlying our analysis are insights for the analysis of non-convex optimization schemes that may have implications for computational problems beyond phase retrieval.

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An automated and robust method for modelling X-ray beamlines with plane grating monochromators.

2025-07-01

Patrick Yuheng Wang , Murilo Bazan da Silva , Georg Held +3 more

The plane grating monochromator (PGM) is an optical instrument used in the majority of soft X-ray beamlines. Despite its ubiquity, the PGM efficiency can easily be overestimated, because the geometry … The plane grating monochromator (PGM) is an optical instrument used in the majority of soft X-ray beamlines. Despite its ubiquity, the PGM efficiency can easily be overestimated, because the geometry of many modern PGMs can lead to unexpected blocking of the beam. We have developed a new workflow in Python for simulating PGMs, thus extending the capabilities of SHADOW3, a well established ray tracing software tool. We have used our method to simulate the flux on branch C of the Versatile Soft X-ray (VerSoX) beamline B07 at Diamond Light Source. The simulation results demonstrate qualitative agreement with the experimental measurements, confirming the robustness of the proposed methodology.

Real‐Time Tracking of Nanoscale Morphology and Strain Evolution in Bi<sub>2</sub>WO<sub>6</sub> via Operando Coherent X‐Ray Imaging

2025-06-24

John B. Anderson , Nimish P. Nazirkar , Atoumane Ndiaye +7 more | Advanced Materials

Abstract Nanostructuring photocatalytic and catalytic materials substantially increases the surface‐to‐volume ratio, thereby exposing a greater number of active sites essential for enhanced catalytic efficiency. However, optimizing these efficiencies requires the … Abstract Nanostructuring photocatalytic and catalytic materials substantially increases the surface‐to‐volume ratio, thereby exposing a greater number of active sites essential for enhanced catalytic efficiency. However, optimizing these efficiencies requires the non‐destructive, operando interrogation of individual nanocrystals under realistic catalytic conditions—a capability that has long remained elusive. Here, this challenge is addressed by reporting three‐dimensional imaging of defects, crystal morphology, and strain dynamics in individual Bi 2 WO 6 (BWO) nanoflakes using Bragg coherent diffractive imaging (BCDI) under operando temperature, gas, and light‐driven conditions. It is demonstrated that maintaining a constant temperature of 40°C thermally activates charge carriers, likely enhancing their mobility and reducing recombination rates. Furthermore, an Argon (Ar) gas flow stabilizes the reaction environment, while a mixed Hydrogen–Nitrogen (H 2 + N 2 ) flow induces a hydrogen‐triggered semiconducting‐to‐metallic (SM) electronic phase transition accompanied by a structural transformation, as supported by density functional theory (DFT) calculations. Both DFT and BCDI analyses reveal that during the SM phase transition, a new structural phase nucleates near defects and propagates inhomogeneously. Notably, the onset of nanoscale cracking is observed, driven by localized strain accumulation and environmental cycling, which increases surface area and potentially introduces new reactive sites. These findings illustrate that combining advanced nanostructuring with operando imaging techniques can provide critical insights into the local structural features that govern photocatalytic performance, paving the way for the rational design of next‐generation photocatalytic materials.

First lasing and stable operation of a direct-amplification enabled harmonic generation free-electron laser

2025-06-24

NULL AUTHOR_ID | Physical Review Letters

Fourier ptychography microscopy for digital pathology

2025-06-24

Fraser Eadie , Laura Copeland , Giuseppe Di Caprio +2 more | Journal of Microscopy

Abstract Fourier ptychography microscopy (FPM) has made significant progress since its invention in 2013, thanks to its adaptable nature, high resolution, and vast field‐of‐view capabilities. FPM is used in various … Abstract Fourier ptychography microscopy (FPM) has made significant progress since its invention in 2013, thanks to its adaptable nature, high resolution, and vast field‐of‐view capabilities. FPM is used in various medical applications across multiple optical wavelengths, from automated digital pathology to radiology and ultraviolet label‐free imaging. This review explores the fundamental physical and computational concepts that have driven advancements in digital pathology using FPM. A crucial part of the progress has been the development of computational algorithms, which have directly contributed to the improvements in FPM. We evaluate early‐stage algorithms like the Gerchberg–Saxton and highlight how phase‐retrieval and deep‐learning advancements have propelled FPM forward. Additionally, we discuss the impact of these algorithms on digital pathology for potential automated diagnosis, providing a comprehensive explanation of their influence on medical imaging and offering insights into future research directions.

Strategies for Suppression and Compensation of Signal Loss in Ptychography

2025-06-23

Ruoru Li , Zijian Xu , Sheng Chen +4 more | Photonics

X-ray ptychography is an ultrahigh resolution imaging technique widely used in synchrotron radiation facilities. Its imaging performance relies on the quality of the acquired signals. However, the X-ray detectors used … X-ray ptychography is an ultrahigh resolution imaging technique widely used in synchrotron radiation facilities. Its imaging performance relies on the quality of the acquired signals. However, the X-ray detectors used often suffer from signal loss due to sensor gaps, beamstops, defective pixels, overexposure, or other factors, resulting in degraded image quality. To suppress and compensate for the effects of signal loss, we proposed the known probe approach to partially recover the lost signals and introduced the high probe divergence strategy by investigating the effects of probe divergence on reconstruction quality under signal loss conditions. Both simulation and experiment results show that high probe divergence can effectively suppress the impact of signal loss on reconstruction quality while using a known probe as the initial probe for reconstruction can largely recover missing signals in Fourier space, resulting in a much better image than using a guessed initial probe. These strategies allow for high-quality imaging in the presence of signal loss without secondary data acquisition, significantly improving experimental efficiency and reducing radiation damage compared to previous strategies.

Gain of squeezing via photon subtraction

2025-06-23

M. S. Podoshvedov , Sergey A. Podoshvedov , S. P. Kulik | Journal of the Optical Society of America B

How X-ray dark-field imaging relates to small-angle X-ray scattering measurements

2025-06-20

Clara Magnin , Manuel Fernández Martínez , Dan Mihai Cenda +4 more | Journal of Applied Crystallography

Dark-field (DF) imaging is a recent X-ray imaging modality which is promising because it gives access to information not resolved in conventional transmission X-ray imaging. The DF technique was first … Dark-field (DF) imaging is a recent X-ray imaging modality which is promising because it gives access to information not resolved in conventional transmission X-ray imaging. The DF technique was first introduced as a loss of visibility of the grating interferometry modulations. DF signal is now measured with all the different X-ray phase contrast setups such as beam tracking or modulation-based imaging. Using a dedicated setup [Magnin et al. (2023). Opt. Lett. 48 , 5839–5842], we present in the present article combined measurements of small-angle X-ray scattering and DF signal on the same material. We confirm that DF imaging is sensitive to multiple refraction from a sample, as can be found in the literature on lung imaging, but we show that the DF signal is also sensitive to scattering events. Finally, we measure a porous membrane that creates both types of signal (scattering and refraction), showing that, contrary to existing models, it is difficult to be quantitative about DF.

Phase retrieval via media diversity

2025-06-20

Yan Cheng , Kui Ren , Nathan Soedjak | Inverse Problems

Abstract This work studies phase retrieval for wave fields, aiming to recover the phase of an incoming wave from multi-plane intensity measurements behind different types of linear and nonlinear media. … Abstract This work studies phase retrieval for wave fields, aiming to recover the phase of an incoming wave from multi-plane intensity measurements behind different types of linear and nonlinear media. We show that unique phase retrieval can be achieved by utilizing intensity data produced by multiple media. This uniqueness does not require prescribed boundary conditions for the phase in the incidence plane, in contrast to existing phase retrieval methods based on the transport of intensity equation. Moreover, the uniqueness proofs lead to explicit phase reconstruction algorithms. Numerical simulations are presented to validate the theory.

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Suppressing system instability in ptychography using least-squares inverse solution

2025-06-19

Haonan Zhang , Haixiao Deng , Chao Zhang +5 more | Optics Express

Development of Wolter I X-ray focusing mirror using the nickel replica in IHEP

2025-06-18

Yanji Yang , Yu Ke , Juan Wang +7 more | Radiation Detection Technology and Methods

All hard X-ray transient grating spectroscopy

2025-06-18

Eugenio Ferrari , Hiroki Ueda , Danny Fainozzi +7 more | Communications Physics

Abstract Optical-domain transient grating (TG) spectroscopy is the ideal tool to investigate transport phenomena in gases, liquids and solids, but it is limited to typically micron-size grating periods. Extreme-Ultraviolet TG … Abstract Optical-domain transient grating (TG) spectroscopy is the ideal tool to investigate transport phenomena in gases, liquids and solids, but it is limited to typically micron-size grating periods. Extreme-Ultraviolet TG has represented a major leap forward to access the mesoscopic scales. Hard X-ray TGs open access in principle to the nanoscale. Hard X-ray TGs were recently generated using the Talbot effect and probed by optical pulses, but these hinder exploiting the advantages of the nanoscale gratings. Here, we present an all-X-ray TG study, in which few-femtosecond hard X-ray pulses are used both for excitation and probing. Our experiment was performed on an amorphous film of an FeGd alloy and on a thin silicon single crystal. The results show a manifestation of the TG induced by the X-ray pump and probe pulses in the form of Talbot carpets, as well as temporal evolution of the grating in crystalline silicon showing coherent optical phonons. Ultrafast all-X-ray TG spectroscopy has the potential to study fundamental excitations with femtosecond time resolution and nanometer spatial sensitivity.

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FPGA-accelerated SpeckleNN with SNL for real-time X-ray single-particle imaging

2025-06-18

Abhilasha Dave , Cong Wang , J. J. Russell +2 more | Frontiers in High Performance Computing

We present the implementation of a specialized version of our previously published unified embedding model, SpeckleNN, for real-time speckle pattern classification in X-ray Single-Particle Imaging (SPI), using the SLAC Neural … We present the implementation of a specialized version of our previously published unified embedding model, SpeckleNN, for real-time speckle pattern classification in X-ray Single-Particle Imaging (SPI), using the SLAC Neural Network Library (SNL) on an FPGA platform. This hardware realization transitions SpeckleNN from a prototypic model into a practical edge solution, optimized for running inference near the detector in high-throughput X-ray free-electron laser (XFEL) facilities, such as those found at the Linac Coherent Light Source (LCLS). To address the resource constraints inherent in FPGAs, we developed a more specialized version of SpeckleNN. The original model, which was designed for broader classification across multiple biological samples, comprised ~5.6 million parameters. The new implementation, while reducing the parameter count to 64.6K (a 98.8% reduction), focuses on maintaining the model's essential functionality for real-time operation, achieving an accuracy of 90%. Furthermore, we compressed the latent space from 128 to 50 dimensions. This implementation was demonstrated on the KCU1500 FPGA board, utilizing 71% of available DSPs, 75% of LUTs, and 48% of FFs, with an average power consumption of 9.4W according to the Vivado post-implementation report. The FPGA performed inference on a single image with a latency of 45.015 microseconds at a 200 MHz clock rate. In comparison, running the same inference on an NVIDIA A100 GPU resulted in an average power consumption of ~73W and an image processing latency of around 400 microseconds. Our FPGA-accelerated version of SpeckleNN demonstrated significant improvements, achieving an 8.9 × speedup and a 7.8 × reduction in power consumption compared to the GPU implementation. Key advancements include model specialization and dynamic weight loading through SNL, which eliminates the need for time-consuming FPGA design re-synthesis, allowing fast and continuous deployment of models (re)trained online. These innovations enable real-time adaptive classification and efficient vetoing of speckle patterns, making SpeckleNN more suited for deployment in XFEL facilities. This implementation has the potential to significantly accelerate SPI experiments and enhance adaptability to evolving experimental conditions.

A Halpha metric for identifying dormant black holes in X-ray transients

2025-06-17

J. Casares , M. A. P. Torres , S. Navarro Umpierrez | Astronomy and Astrophysics

Dormant black holes in X-ray transients can be identified by the presence of broad emission lines from quiescent accretion discs. Unfortunately, short-period cataclysmic variables can also produce broad lines, especially … Dormant black holes in X-ray transients can be identified by the presence of broad emission lines from quiescent accretion discs. Unfortunately, short-period cataclysmic variables can also produce broad lines, especially when viewed at high inclinations, and are thus a major source of contamination. Here we compare the full width at half maximum (FWHM) and equivalent width (EW) of the line in a sample of 20 quiescent black hole transients and 354 cataclysmic variables (305 from SDSS I to IV) with secure orbital periods (P_ orb) and find that: (1) FWHM and EW values decrease with P_ orb, and (2) for a given P_ orb both parameters are typically larger in black hole transients than in cataclysmic variables. We also compile spectral types for 17 low-mass companions in black hole transients from the literature and derive an empirical orb -T_ eff calibration. Using this, we conclude that the decrease in EW with P_ orb is mostly driven by the dilution of the flux by the donor star continuum, which dominates the r-band spectrum for orb ≳0.2 d. At shorter periods, the larger contribution of the disc to the total r-band flux introduces significant scatter in the EWs due to the changing visibility of the disc projected area with binary inclination. On the other hand, the larger EWs observed in black holes can be explained by their extreme mass ratios (which limit the fractional contribution of the companion to the total flux) and the absence of a white dwarf component (important at P_ orb d). Finally, we present a tentative metric, based on FWHM and EW information, and provide optimal cuts to select ∼80 % of the black hole X-ray transients, while rejecting ∼78 % of the cataclysmic variables in our sample. Such a metric, combined with other multi-frequency diagnostics, can help detect new dormant black hole X-ray transients in blind large-scale surveys such as α $WKs and its pathfinder, Mini-H$ α $WKs.

Processing-dependent chemical ordering in Cu3Au characterized via non-destructive Bragg coherent diffraction imaging

2025-06-17

N. Warren , Chloe Skidmore , Katherine Harmon +4 more | Scripta Materialia

Measurement of the 10B(d,n)11C reaction cross-section in the energy range of 0.05–0.57 MeV in inverse kinematics

2025-06-16

Pavel Prusachenko , A.F. Gurbich , T. L. Bobrovskiy +1 more | Applied Radiation and Isotopes

femto-PIXAR: a self-supervised neural network method for reconstructing femtosecond X-ray free electron laser pulses

2025-06-16

Gesa Goetzke , Rajan Plumley , Gregor Hartmann +6 more | Optics Express

Radial-balanced phase transfer functions for accurate retrieval in quantitative differential phase contrast microscopy

2025-06-16

Cheng Yu , Ching‐En Lin , Sunil Vyas +2 more | Optics Express

Real-Time 3D Coherent X-Ray Diffraction Imaging

2025-06-12

Fangzhou Ai , Oleg Shpyrko , Vitaliy Lomakin | Physical Review Letters

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Phase-Augmented Deep Learning for Cell Segmentation in Wrapped Quantitative Phase Images

2025-06-12

Daniel Alexandre Baptista Bonifácio , Laterriean Minaya , Chen Xue-mei +2 more | Biomedical Optics Express

Phase retrieval by designed Hadamard complementary coded apertures

2025-06-12

Bastián Romero , Pablo Scherz , Nelson Díaz +5 more | Optics & Laser Technology

Sparse X-ray Spectro-Tomography for High-Sensitivity Three-Dimensional Chemical Imaging at the Nanoscale

2025-06-03

Hanfei Yan , Ajith Pattammattel , Aaron Michelson +2 more | Research Square (Research Square)

<title>Abstract</title> Achieving three-dimensional (3D) chemical imaging with scanning x-ray microscopy is often hindered by the prohibitively long acquisition time. In this work, we develop a method that drastically reduces the … <title>Abstract</title> Achieving three-dimensional (3D) chemical imaging with scanning x-ray microscopy is often hindered by the prohibitively long acquisition time. In this work, we develop a method that drastically reduces the data requirement by two orders of magnitude, making such measurement practically feasible. This is accomplished through sparse and stochastic energy sampling combined with a joint spectral-tomographic reconstruction algorithm. Using this approach, we reveal the reduced oxidation state of Co on the surface of a cycled lithium-ion battery particle and its correlation with the depletion of Mn in 3D. This technique enables comprehensive 3D material characterization with high sensitivity and multimodality, opening opportunities in various scientific and technological fields where volumetric chemical information at the nanoscale is essential.