scholarly journals Near, far, wherever you are: simulations on the dose efficiency of holographic and ptychographic coherent imaging

2020 ◽  
Vol 53 (3) ◽  
pp. 748-759 ◽  
Author(s):  
Ming Du ◽  
Dogˇa Gürsoy ◽  
Chris Jacobsen
Keyword(s):  
Spatial Resolution ◽  
Numerical Study ◽  
Near Field ◽  
Far Field ◽  
Coherent Imaging ◽  
Coherent Diffraction Imaging ◽  
Dose Efficiency ◽  
Photon Fluence ◽  
Diffraction Imaging ◽  
Similar Image Quality

Different studies in X-ray microscopy have arrived at conflicting conclusions about the dose efficiency of imaging modes involving the recording of intensity distributions in the near (Fresnel regime) or far (Fraunhofer regime) field downstream of a specimen. A numerical study is presented on the dose efficiency of near-field holography, near-field ptychography and far-field ptychography, where ptychography involves multiple overlapping finite-sized illumination positions. Unlike what has been reported for coherent diffraction imaging, which involves recording a single far-field diffraction pattern, it is found that all three methods offer similar image quality when using the same fluence on the specimen, with far-field ptychography offering slightly better spatial resolution and a lower mean error. These results support the concept that (if the experiment and image reconstruction are done properly) the sample can be near or far; wherever you are, photon fluence on the specimen sets one limit to spatial resolution.

scholarly journals The Nanodiffraction beamline ID01/ESRF: a microscope for imaging strain and structure

2019 ◽  
Vol 26 (2) ◽  
pp. 571-584 ◽  
Author(s):  
Steven J. Leake ◽  
Gilbert A. Chahine ◽  
Hamid Djazouli ◽  
Tao Zhou ◽  
Carsten Richter ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Imaging Techniques ◽  
Bragg Diffraction ◽  
Scanning Probe ◽  
Objective Lens ◽  
Full Field ◽  
User Community ◽  
Coherent Diffraction Imaging ◽  
Diffraction Imaging ◽  
Focused Beams

The ID01 beamline has been built to combine Bragg diffraction with imaging techniques to produce a strain and mosaicity microscope for materials in their native or operando state. A scanning probe with nano-focused beams, objective-lens-based full-field microscopy and coherent diffraction imaging provide a suite of tools which deliver micrometre to few nanometre spatial resolution combined with 10−5 strain and 10−3 tilt sensitivity. A detailed description of the beamline from source to sample is provided and serves as a reference for the user community. The anticipated impact of the impending upgrade to the ESRF – Extremely Brilliant Source is also discussed.

scholarly journals Numerical Study on the Longitudinal Response Characteristics of Utility Tunnel under Strong Earthquake: A Case Study

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Guoyi Tang ◽  
Yumei Fang ◽  
Yi Zhong ◽  
Jie Yuan ◽  
Bin Ruan ◽  
...  
Keyword(s):  
Seismic Response ◽  
Strong Earthquake ◽  
Numerical Study ◽  
Soft Soil ◽  
Near Field ◽  
Element Model ◽  
Far Field ◽  
Response Characteristics ◽  
Longitudinal Response ◽  
Utility Tunnel

In this paper, the longitudinal seismic response characteristics of utility tunnel subjected to strong earthquake was investigated based on a practical utility tunnel project and numerical method. Firstly, the generalized response displacement method (GRDM) that was used to conduct this study was reviewed briefly. Secondly, the information of the referenced engineering and the finite element model was introduced in detail, where a novel method to model the joints between utility tunnel segments was presented. Thirdly, a series of seismic response of the utility tunnel were provided, including inner force and intersegment opening width. The results showed that (i) the seismic response of the utility tunnel under far-field earthquake may be remarkable and even higher than that under near-field earthquake; (ii) sharp variation of response may occur at the interface between “soft” soil and “hard” soil, and the variation under far-field earthquake could be much more significant. This research provides a reference for the scientific study and design of relevant engineering.

Near-Field Scanning Optical Microscopy

1987 ◽  
Vol 45 ◽  
pp. 184-187
Author(s):  
E. Betzig ◽  
M. Isaacson ◽  
A. Lewis ◽  
K. Lin
Keyword(s):  
Spatial Resolution ◽  
Structural Damage ◽  
Near Field ◽  
Far Field ◽  
Resolution Limit ◽  
Field Methods ◽  
General Applicability ◽  
Minimal Sample ◽  
Near Field Imaging ◽  
Field Imaging

The spatial resolution of most of the imaging or microcharacterization methods presently in use are fundamentally limited by the wavelength of the exciting or the emitted radiation being used. In general, the smaller the wavelength of the exciting probe, the greater the structural damage to the sample under study. Thus, the requirements of minimal sample alteration and high spatial resolution seem to be at odds with one another.However, the reason for this wavelength resolution limit is due to the far field methods for producing or detecting the radiation of interest. If one does not use far field optics, but rather the method of near field imaging, the spatial resolution attainable can be much smaller than the wavelength of the radiation used. This method of near field imaging has a general applicability for all wave probes.

scholarly journals Numerical Study of the Near-Field and Far-Field Properties of Active Open Cylindrical Coated Nanoparticle Antennas

2011 ◽  
Vol 3 (6) ◽  
pp. 1093-1110 ◽  
Author(s):  
Junping Geng ◽  
R. W. Ziolkowski ◽  
Ronghong Jin ◽  
Xianling Liang
Keyword(s):  
Numerical Study ◽  
Near Field ◽  
Far Field ◽  
Coated Nanoparticle

scholarly journals Nanoscale Spatial Resolution in Far-Field Raman Imaging Using Hyperspectral Unmixing in Combination with Positivity Constrained Super-Resolution

2020 ◽  
Vol 74 (7) ◽  
pp. 780-790
Author(s):  
Dominik J. Winterauer ◽  
Daniel Funes-Hernando ◽  
Jean-Luc Duvail ◽  
Saïd Moussaoui ◽  
Tim Batten ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Spatial Resolution ◽  
Single Channel ◽  
Near Field ◽  
Resolution Enhancement ◽  
Super Resolution ◽  
Resolving Power ◽  
Far Field ◽  
Hyperspectral Unmixing ◽  
Better Than

This work introduces hyper-resolution (HyRes), a numerical approach for spatial resolution enhancement that combines hyperspectral unmixing and super-resolution image restoration (SRIR). HyRes yields a substantial increase in spatial resolution of Raman spectroscopy while simultaneously preserving the undistorted spectral information. The resolving power of this technique is demonstrated on Raman spectroscopic data from a polymer nanowire sample. Here, we demonstrate an achieved resolution of better than 14 nm, a more than eightfold improvement on single-channel image-based SRIR and [Formula: see text] better than regular far-field Raman spectroscopy, and comparable to near-field probing techniques.

scholarly journals Near-field limitations of Fresnel-regime coherent diffraction imaging

2017 ◽  
Vol 96 (5) ◽  
Author(s):  
Benjamin A. Pound ◽  
John L. Barber ◽  
Kimberly Nguyen ◽  
Matthew C. Tyson ◽  
Richard L. Sandberg
Keyword(s):  
Near Field ◽  
Coherent Diffraction Imaging ◽  
Diffraction Imaging

scholarly journals Near-Field IR Orientational Spectroscopy of Silk

2019 ◽  
Author(s):  
Meguya Ryu ◽  
Reo Honda ◽  
Aina Reich ◽  
Adrian Cernescu ◽  
Jing-Liang Li ◽  
...  
Keyword(s):  
Optical Microscopy ◽  
Spatial Resolution ◽  
Cross Sections ◽  
Molecular Orientation ◽  
Near Field ◽  
Beta Sheets ◽  
Far Field ◽  
Absorbance Measurement

Orientational dependence of the IR absorbing amide bands of silk is demonstrated from two orthogonal longitudinal and transverse microtome slices only $\sim 100$~nm thick. A scanning near-field optical microscopy (SNOM) which preferentially probes orientation perpendicular to the sample's surface was used. Spatial resolution of silk-epoxy boundary was defined with a $\sim 100$~nm resolution while the spectra were collected by a $\sim 10$~nm tip. Ratio of the absorbance of the amide-II C-N at 1512~cm$^{-1}$ and amide-I C=O $\beta$-sheets at 1628~cm$^{-1}$ showed sensitivity of SNOM to the molecular orientation. SNOM characterisation is complimentary to the far-field absorbance which is sensitive to the in-plane polarisation. Volumes with cross sections smaller than 100~nm can be characterised for molecular orientation. A method of absorbance measurements at four angles of slice cut orientation, which is equivalent to the four polarisation angles absorbance measurement is proposed.

scholarly journals The fluence–resolution relationship in holographic and coherent diffractive imaging

2017 ◽  
Vol 50 (2) ◽  
pp. 531-538 ◽  
Author(s):  
Johannes Hagemann ◽  
Tim Salditt
Keyword(s):  
Phase Retrieval ◽  
Numerical Study ◽  
Imaging Techniques ◽  
Near Field ◽  
Superior Performance ◽  
Phase Reconstruction ◽  
Reconstruction Procedure ◽  
Diffractive Imaging ◽  
Coherent Diffractive Imaging ◽  
Photon Fluence

This work presents a numerical study of the fluence–resolution behaviour for two coherent lensless X-ray imaging techniques. To this end the fluence–resolution relationship of inline near-field holography and far-field coherent diffractive imaging are compared in numerical experiments. To achieve this, the phase reconstruction is carried out using iterative phase-retrieval algorithms on simulated noisy data. Using the incident photon fluence on the specimen as the control parameter, the achievable resolution for two example phantoms (cell and bitmap) is studied. The results indicate the superior performance of holography compared with coherent diffractive imaging, for the same fluence and phase-reconstruction procedure.

scholarly journals Experimental and numerical study of rotor aeroacoustics

2017 ◽  
Vol 16 (6) ◽  
pp. 460-475 ◽  
Author(s):  
Robert Stepanov ◽  
Vladimir Pakhov ◽  
Andrey Bozhenko ◽  
Andrey Batrakov ◽  
Lyaysan Garipova ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Resolution ◽  
Numerical Study ◽  
Near Field ◽  
Far Field ◽  
Acoustic Data ◽  
Technical University ◽  
Helicopter Acoustics

The work documents recent experiments at the Kazan National Research Technical University named after A.N. Tupolev (Kazan Aviation Institute), related to helicopter acoustics. The objective is to measure nar-field acoustics of rotors in hover and provide data suitable for computational fluid dynamics validation. The obtained set of data corresponds to a scaled rotor of known planform and the results are of high resolution. An advantage of the current dataset is that direct near-field acoustic data is made available and this allows for easy and direct comparisons with computational fluid dynamics predictions, without the need to use far-field aeroacoustic methods.

scholarly journals Near-Field IR Orientational Spectroscopy of Silk

2019 ◽  
Vol 9 (19) ◽  
pp. 3991 ◽  
Author(s):  
Meguya Ryu ◽  
Reo Honda ◽  
Aina Reich ◽  
Adrian Cernescu ◽  
Jing-Liang Li ◽  
...  
Keyword(s):  
Optical Microscopy ◽  
Spatial Resolution ◽  
Cross Sections ◽  
Molecular Orientation ◽  
Near Field ◽  
Far Field ◽  
Absorbance Measurement ◽  
Β Sheets

Orientational dependence of the IR absorbing amide bands of silk is demonstrated from two orthogonal longitudinal and transverse microtome slices with a thickness of only ∼100 nm. Scanning near-field optical microscopy (SNOM) which preferentially probes orientation perpendicular to the sample’s surface was used. Spatial resolution of the silk–epoxy boundary was ∼100 nm resolution, while the spectra were collected by a ∼10 nm tip. Ratio of the absorbance of the amide-II C-N at 1512 cm − 1 and amide-I C=O β -sheets at 1628 cm − 1 showed sensitivity of SNOM to the molecular orientation. SNOM characterisation is complimentary to the far-field absorbance which is sensitive to the in-plane polarisation. Volumes with cross sections smaller than 100 nm can be characterised for molecular orientation. A method of absorbance measurements at four angles of the slice cut orientation, which is equivalent to the four polarisation angles absorbance measurement, is proposed.

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