Gauging diffraction patterns: field of view and bandwidth estimation in lensless holography

Abstract X-ray ptychography is a rapidly developing coherent diffraction imaging technique that provides nanoscale resolution on extended field-of-view. However, the requirement of coherence and the scanning mechanism limit the throughput of ptychographic imaging. In this paper, we propose X-ray ptychography using multiple illuminations instead of single illumination in conventional ptychography. Multiple locations of the sample are simultaneously imaged by spatially separated X-ray beams, therefore, the obtained field-of-view in one scan can be enlarged by a factor equal to the number of illuminations. We have demonstrated this technique experimentally using two X-ray beams focused by a house-made Fresnel zone plate array. Two areas of the object and corresponding double illuminations were successfully reconstructed from diffraction patterns acquired in one scan, with image quality similar with those obtained by conventional single-beam ptychography in sequence. Multi-beam ptychography approach increases the imaging speed, providing an efficient way for high-resolution imaging of large extended specimens.

Download Full-text

Upsampling speckle patterns for coherent X-ray diffraction imaging

Journal of Applied Crystallography ◽

10.1107/s0021889813003117 ◽

2013 ◽

Vol 46 (2) ◽

pp. 319-323 ◽

Cited By ~ 8

Author(s):

Y. Chushkin ◽

F. Zontone

Keyword(s):

Diffraction Pattern ◽

Imaging Technique ◽

Real Space ◽

Field Of View ◽

Combination Method ◽

Pixel Size ◽

X Ray Diffraction ◽

X Ray ◽

Diffraction Imaging ◽

Diffraction Patterns

Coherent X-ray diffraction imaging is a lensless imaging technique where an iterative phase-retrieval algorithm is applied to the speckle pattern, the far-field diffraction pattern produced by an isolated object. To ensure convergence to a unique solution, the diffraction pattern must be oversampled by a factor of two or more. Since the resolution in real space depends on the maximum wave vector where the intensity is detected,i.e.on the detector field of view, there is a practical limitation on oversampling in reciprocal space and resolution in real space that is ultimately determined by the number of pixels. This work shows that it is possible to reduce the effective pixel size and maintain the detector field of view by applying a linear combination method to shifted diffraction patterns. The feasibility of the method is demonstrated by reconstructing the images of test objects from diffraction patterns oversampled in each dimension by factors of 1.3 and 1.8 only. The described approach can be applied to any diffraction or imaging technique where the resolution is compromised by a large pixel size.

Download Full-text

Deep transfer learning-based hologram classification for molecular diagnostics

10.1101/192559 ◽

2017 ◽

Author(s):

Sung-Jin Kim ◽

Chuangqi Wang ◽

Bing Zhao ◽

Hyungsoon Im ◽

Jouha Min ◽

...

Keyword(s):

Transfer Learning ◽

Point Of Care ◽

Low Cost ◽

Field Of View ◽

Robust Performance ◽

Resource Limited Settings ◽

Resource Limited ◽

Point Of Care Diagnostics ◽

Diffraction Patterns ◽

Extensive Computation

ABSTRACTLens-free digital in-line holography (LDIH) is a promising microscopic tool that overcomes several drawbacks (e.g., limited field of view) of traditional lens-based microcopy. However, extensive computation is required to reconstruct object images from the complex diffraction patterns produced by LDIH, which limits LDIH utility for point-of-care applications, particularly in resource limited settings. Here, we describe a deep transfer learning (DTL) based approach to process LDIH images in the context of cellular analyses. Specifically, we captured holograms of cells labeled with molecular-specific microbeads and trained neural networks to classify these holograms without reconstruction. Using raw holograms as input, the trained networks were able to classify individual cells according to the number of cell-bound microbeads. The DTL-based approach including a VGG19 pretrained network showed robust performance even with noisy experimental data. Combined with the developed DTL approach, LDIH could be realized as a low-cost, portable tool for point-of-care diagnostics.

Download Full-text

Very High Resolution Analysis of the Dynamics of a Coronal Plasmoid

International Astronomical Union Colloquium ◽

10.1017/s0252921100026117 ◽

1994 ◽

Vol 144 ◽

pp. 593-596

Author(s):

O. Bouchard ◽

S. Koutchmy ◽

L. November ◽

J.-C. Vial ◽

J. B. Zirker

Keyword(s):

High Resolution ◽

Solar Eclipse ◽

Total Solar Eclipse ◽

Field Of View ◽

Small Field ◽

High Resolution Analysis ◽

Ccd Observations ◽

Resolution Analysis ◽

Very High ◽

Small Field Of View

AbstractWe present the results of the analysis of a movie taken over a small field of view in the intermediate corona at a spatial resolution of 0.5“, a temporal resolution of 1 s and a spectral passband of 7 nm. These CCD observations were made at the prime focus of the 3.6 m aperture CFHT telescope during the 1991 total solar eclipse.

Download Full-text

Light Optical Diffraction Studies of Macromolecular Ultrastructure

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010006828x ◽

1970 ◽

Vol 28 ◽

pp. 258-259

Author(s):

Glen B. Haydon

Keyword(s):

High Resolution ◽

Diffraction Analysis ◽

Diffraction Pattern ◽

Electron Micrographs ◽

Optical Diffraction ◽

Electron Micrograph ◽

Its Analysis ◽

Resolution Electron ◽

Diffraction Patterns

Analysis of light optical diffraction patterns produced by electron micrographs can easily lead to much nonsense. Such diffraction patterns are referred to as optical transforms and are compared with transforms produced by a variety of mathematical manipulations. In the use of light optical diffraction patterns to study periodicities in macromolecular ultrastructures, a number of potential pitfalls have been rediscovered. The limitations apply to the formation of the electron micrograph as well as its analysis.(1) The high resolution electron micrograph is itself a complex diffraction pattern resulting from the specimen, its stain, and its supporting substrate. Cowley and Moodie (Proc. Phys. Soc. B, LXX 497, 1957) demonstrated changing image patterns with changes in focus. Similar defocus images have been subjected to further light optical diffraction analysis.

Download Full-text

Electron microscopy and diffraction studies of polyimides

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100074069 ◽

1983 ◽

Vol 41 ◽

pp. 28-29

Author(s):

O.C. de Hodgins ◽

K. R. Lawless ◽

R. Anderson

Keyword(s):

Electron Microscopy ◽

Electron Microscope ◽

Structural Features ◽

Inert Atmosphere ◽

Polyimide Films ◽

Resolution Electron ◽

The Matrix ◽

High Resolution Electron Microscope ◽

Diffraction Patterns ◽

Polymeric Samples

Commercial polyimide films have shown to be homogeneous on a scale of 5 to 200 nm. The observation of Skybond (SKB) 705 and PI5878 was carried out by using a Philips 400, 120 KeV STEM. The objective was to elucidate the structural features of the polymeric samples. The specimens were spun and cured at stepped temperatures in an inert atmosphere and cooled slowly for eight hours. TEM micrographs showed heterogeneities (or nodular structures) generally on a scale of 100 nm for PI5878 and approximately 40 nm for SKB 705, present in large volume fractions of both specimens. See Figures 1 and 2. It is possible that the nodulus observed may be associated with surface effects and the structure of the polymers be regarded as random amorphous arrays. Diffraction patterns of the matrix and the nodular areas showed different amorphous ring patterns in both materials. The specimens were viewed in both bright and dark fields using a high resolution electron microscope which provided magnifications of 100,000X or more on the photographic plates if desired.

Download Full-text

Two Investigations into Grain Boundary Structure

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100080833 ◽

1977 ◽

Vol 35 ◽

pp. 688-691

Author(s):

P. Humble

Keyword(s):

Grain Boundary ◽

Dark Field ◽

Boundary Structure ◽

Boundary Dislocation ◽

Bright Field ◽

Intrinsic Structure ◽

Weak Beam ◽

Grain Boundary Structure ◽

Independent Information ◽

Diffraction Patterns

There has been sustained interest over the last few years into both the intrinsic (primary and secondary) structure of grain boundaries and the extrinsic structure e.g. the interaction of matrix dislocations with the boundary. Most of the investigations carried out by electron microscopy have involved only the use of information contained in the transmitted image (bright field, dark field, weak beam etc.). Whilst these imaging modes are appropriate to the cases of relatively coarse intrinsic or extrinsic grain boundary dislocation structures, it is apparent that in principle (and indeed in practice, e.g. (1)-(3)) the diffraction patterns from the boundary can give extra independent information about the fine scale periodic intrinsic structure of the boundary.In this paper I shall describe one investigation into each type of structure using the appropriate method of obtaining the necessary information which has been carried out recently at Tribophysics.

Download Full-text

Disappearance Voltage Determinations Using a Convergent Beam

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100064979 ◽

1971 ◽

Vol 29 ◽

pp. 184-185

Author(s):

W. L. Bell

Keyword(s):

Second Order ◽

Objective Method ◽

Uniform Thickness ◽

Rocking Curve ◽

Crystal Perfection ◽

Kikuchi Line ◽

Central Maximum ◽

Diffraction Patterns ◽

Convergent Beam ◽

Beam Technique

Disappearance voltages for second order reflections can be determined experimentally in a variety of ways. The more subjective methods, such as Kikuchi line disappearance and bend contour imaging, involve comparing a series of diffraction patterns or micrographs taken at intervals throughout the disappearance range and selecting that voltage which gives the strongest disappearance effect. The estimated accuracies of these methods are both to within 10 kV, or about 2-4%, of the true disappearance voltage, which is quite sufficient for using these voltages in further calculations. However, it is the necessity of determining this information by comparisons of exposed plates rather than while operating the microscope that detracts from the immediate usefulness of these methods if there is reason to perform experiments at an unknown disappearance voltage.The convergent beam technique for determining the disappearance voltage has been found to be a highly objective method when it is applicable, i.e. when reasonable crystal perfection exists and an area of uniform thickness can be found. The criterion for determining this voltage is that the central maximum disappear from the rocking curve for the second order spot.

Download Full-text

Electronic Cone Illumination with the Conventional Transmission Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100077980 ◽

1977 ◽

Vol 35 ◽

pp. 72-73

Author(s):

William Krakow

Keyword(s):

Electronic Device ◽

Chromatic Aberration ◽

Objective Lens ◽

Hollow Cone ◽

Transmission Electron ◽

Lissajous Figures ◽

High Resolution Images ◽

Imaging Mode ◽

Diffraction Patterns ◽

Transmission Microscope

An electronic device has been constructed which manipulates the primary beam in the conventional transmission microscope to illuminate a specimen under a variety of virtual condenser aperture conditions. The device uses the existing tilt coils of the microscope, and modulates the D.C. signals to both x and y tilt directions simultaneously with various waveforms to produce Lissajous figures in the back-focal plane of the objective lens. Electron diffraction patterns can be recorded which reflect the manner in which the direct beam is tilted during exposure of a micrograph. The device has been utilized mainly for the hollow cone imaging mode where the device provides a microscope transfer function without zeros in all spatial directions and has produced high resolution images which are also free from the effect of chromatic aberration. A standard second condenser aperture is employed and the width of the cone annulus is readily controlled by defocusing the second condenser lens.

Download Full-text

Computer Indexing of Electron Diffraction Patterns Including the Effects of Lattice Symmetry

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010007775x ◽

1977 ◽

Vol 35 ◽

pp. 22-23

Author(s):

J. S. Lally ◽

R. J. Lee

Keyword(s):

Electron Diffraction ◽

Zone Axis ◽

Crystal Thickness ◽

Double Diffraction ◽

Automated Method ◽

Lattice Symmetry ◽

Intensity Calculations ◽

Unknown Structure ◽

Diffraction Patterns ◽

Orientation Parameters

In the 50 year period since the discovery of electron diffraction from crystals there has been much theoretical effort devoted to the calculation of diffracted intensities as a function of crystal thickness, orientation, and structure. However, in many applications of electron diffraction what is required is a simple identification of an unknown structure when some of the shape and orientation parameters required for intensity calculations are not known. In these circumstances an automated method is needed to solve diffraction patterns obtained near crystal zone axis directions that includes the effects of systematic absences of reflections due to lattice symmetry effects and additional reflections due to double diffraction processes.Two programs have been developed to enable relatively inexperienced microscopists to identify unknown crystals from diffraction patterns. Before indexing any given electron diffraction pattern, a set of possible crystal structures must be selected for comparison against the unknown.

Download Full-text