scholarly journals Complex wavefront sensing based on coherent diffraction imaging using vortex modulation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rujia Li ◽  
Liangcai Cao
Keyword(s):  
Phase Retrieval ◽  
Dynamic Range ◽  
A Priori ◽  
Measured Intensity ◽  
Physical Constraints ◽  
Coherent Diffraction Imaging ◽  
Effective Dynamic ◽  
Ill Posed ◽  
Retrieval Problem ◽  
Diffraction Imaging

AbstractPhase retrieval seeks to reconstruct the phase from the measured intensity, which is an ill-posed problem. A phase retrieval problem can be solved with physical constraints by modulating the investigated complex wavefront. Orbital angular momentum has been recently employed as a type of reliable modulation. The topological charge l is robust during propagation when there is atmospheric turbulence. In this work, topological modulation is used to solve the phase retrieval problem. Topological modulation offers an effective dynamic range of intensity constraints for reconstruction. The maximum intensity value of the spectrum is reduced by a factor of 173 under topological modulation when l is 50. The phase is iteratively reconstructed without a priori knowledge. The stagnation problem during the iteration can be avoided using multiple topological modulations.

scholarly journals Phase retrieval for Bragg coherent diffraction imaging at high x-ray energies

2019 ◽  
Vol 99 (5) ◽  
Author(s):  
S. Maddali ◽  
M. Allain ◽  
W. Cha ◽  
R. Harder ◽  
J.-S. Park ◽  
...  
Keyword(s):  
Phase Retrieval ◽  
X Ray ◽  
Coherent Diffraction Imaging ◽  
Diffraction Imaging

scholarly journals Resolution Enhancement in Coherent Diffraction Imaging Using High Dynamic Range Image

Photonics ◽  
2021 ◽  
Vol 8 (9) ◽  
pp. 370
Author(s):  
Yuanyuan Liu ◽  
Qingwen Liu ◽  
Shuangxiang Zhao ◽  
Wenchen Sun ◽  
Bingxin Xu ◽  
...  
Keyword(s):  
Dynamic Range ◽  
High Dynamic Range ◽  
Image Sensor ◽  
High Dynamic Range Imaging ◽  
Range Imaging ◽  
Imaging Technology ◽  
Coherent Diffraction Imaging ◽  
Diffraction Imaging ◽  
High Dynamic ◽  
Diffraction Patterns

In a coherent diffraction imaging (CDI) system, the information of the sample is retrieved from the diffraction patterns recorded by the image sensor via multiple iterations. The limited dynamic range of the image sensor restricts the resolution of the reconstructed sample information. To alleviate this problem, the high dynamic range imaging technology is adopted to increase the signal-to-noise ratio of the diffraction patterns. A sequence of raw diffraction images with differently exposure time are recorded by the image sensor. Then, they are fused to generate a high quality diffraction pattern based on the response function of the image sensor. With the fused diffraction patterns, the resolution of the coherent diffraction imaging can be effectively improved. The experiments on USAF resolution card is carried out to verify the effectiveness of our proposed method, in which the spatial resolution is improved by 1.8 times using the high dynamic range imaging technology.

scholarly journals Oversampling smoothness: an effective algorithm for phase retrieval of noisy diffraction intensities

2013 ◽  
Vol 46 (2) ◽  
pp. 312-318 ◽  
Author(s):  
Jose A. Rodriguez ◽  
Rui Xu ◽  
Chien-Chun Chen ◽  
Yunfei Zou ◽  
Jianwei Miao
Keyword(s):  
Phase Retrieval ◽  
High Harmonic ◽  
Solution Space ◽  
Real Space ◽  
X Ray ◽  
Coherent Diffraction Imaging ◽  
Wide Range ◽  
Diffraction Imaging ◽  
Correlation Information ◽  
Noise Robust

Coherent diffraction imaging (CDI) is high-resolution lensless microscopy that has been applied to image a wide range of specimens using synchrotron radiation, X-ray free-electron lasers, high harmonic generation, soft X-ray lasers and electrons. Despite recent rapid advances, it remains a challenge to reconstruct fine features in weakly scattering objects such as biological specimens from noisy data. Here an effective iterative algorithm, termed oversampling smoothness (OSS), for phase retrieval of noisy diffraction intensities is presented. OSS exploits the correlation information among the pixels or voxels in the region outside of a support in real space. By properly applying spatial frequency filters to the pixels or voxels outside the support at different stages of the iterative process (i.e.a smoothness constraint), OSS finds a balance between the hybrid input–output (HIO) and error reduction (ER) algorithms to search for a global minimum in solution space, while reducing the oscillations in the reconstruction. Both numerical simulations with Poisson noise and experimental data from a biological cell indicate that OSS consistently outperforms the HIO, ER–HIO and noise robust (NR)–HIO algorithms at all noise levels in terms of accuracy and consistency of the reconstructions. It is expected that OSS will find application in the rapidly growing CDI field, as well as other disciplines where phase retrieval from noisy Fourier magnitudes is needed. TheMATLAB(The MathWorks Inc., Natick, MA, USA) source code of the OSS algorithm is freely available from http://www.physics.ucla.edu/research/imaging.

scholarly journals Novel Fourier-domain constraint for fast phase retrieval in coherent diffraction imaging

2011 ◽  
Vol 19 (20) ◽  
pp. 19330 ◽  
Author(s):  
Tatiana Latychevskaia ◽  
Jean-Nicolas Longchamp ◽  
Hans-Werner Fink
Keyword(s):  
Phase Retrieval ◽  
Fourier Domain ◽  
Fast Phase ◽  
Coherent Diffraction Imaging ◽  
Diffraction Imaging

scholarly journals Towards a quantitative determination of strain in Bragg Coherent X-ray Diffraction Imaging: artefacts and sign convention in reconstructions

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jérôme Carnis ◽  
Lu Gao ◽  
Stéphane Labat ◽  
Young Yong Kim ◽  
Jan P. Hofmann ◽  
...  
Keyword(s):  
Displacement Field ◽  
Phase Retrieval ◽  
Dynamic Range ◽  
Surface Strain ◽  
Three Dimensions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Retrieval Algorithms ◽  
Diffraction Imaging

AbstractBragg coherent X-ray diffraction imaging (BCDI) has emerged as a powerful technique to image the local displacement field and strain in nanocrystals, in three dimensions with nanometric spatial resolution. However, BCDI relies on both dataset collection and phase retrieval algorithms that can induce artefacts in the reconstruction. Phase retrieval algorithms are based on the fast Fourier transform (FFT). We demonstrate how to calculate the displacement field inside a nanocrystal from its reconstructed phase depending on the mathematical convention used for the FFT. We use numerical simulations to quantify the influence of experimentally unavoidable detector deficiencies such as blind areas or limited dynamic range as well as post-processing filtering on the reconstruction. We also propose a criterion for the isosurface determination of the object, based on the histogram of the reconstructed modulus. Finally, we study the capability of the phasing algorithm to quantitatively retrieve the surface strain (i.e., the strain of the surface voxels). This work emphasizes many aspects that have been neglected so far in BCDI, which need to be understood for a quantitative analysis of displacement and strain based on this technique. It concludes with the optimization of experimental parameters to improve throughput and to establish BCDI as a reliable 3D nano-imaging technique.

scholarly journals General approaches for shear-correcting coordinate transformations in Bragg coherent diffraction imaging. Part II

2020 ◽  
Vol 53 (2) ◽  
pp. 404-418 ◽  
Author(s):  
P. Li ◽  
S. Maddali ◽  
A. Pateras ◽  
I. Calvo-Almazan ◽  
S.O. Hruszkewycz ◽  
...  
Keyword(s):  
Phase Retrieval ◽  
Bragg Diffraction ◽  
Fourier Space ◽  
Sampled Data ◽  
Bragg Structure ◽  
Angular Rotation ◽  
Data Set ◽  
Coherent Diffraction Imaging ◽  
Diffraction Imaging ◽  
Orthogonal Frame

X-ray Bragg coherent diffraction imaging (BCDI) has been demonstrated as a powerful 3D microscopy approach for the investigation of sub-micrometre-scale crystalline particles. The approach is based on the measurement of a series of coherent Bragg diffraction intensity patterns that are numerically inverted to retrieve an image of the spatial distribution of the relative phase and amplitude of the Bragg structure factor of the diffracting sample. This 3D information, which is collected through an angular rotation of the sample, is necessarily obtained in a non-orthogonal frame in Fourier space that must be eventually reconciled. To deal with this, the approach currently favored by practitioners (detailed in Part I) is to perform the entire inversion in conjugate non-orthogonal real- and Fourier-space frames, and to transform the 3D sample image into an orthogonal frame as a post-processing step for result analysis. In this article, which is a direct follow-up of Part I, two different transformation strategies are demonstrated, which enable the entire inversion procedure of the measured data set to be performed in an orthogonal frame. The new approaches described here build mathematical and numerical frameworks that apply to the cases of evenly and non-evenly sampled data along the direction of sample rotation (i.e. the rocking curve). The value of these methods is that they rely on the experimental geometry, and they incorporate significantly more information about that geometry into the design of the phase-retrieval Fourier transformation than the strategy presented in Part I. Two important outcomes are (1) that the resulting sample image is correctly interpreted in a shear-free frame and (2) physically realistic constraints of BCDI phase retrieval that are difficult to implement with current methods are easily incorporated. Computing scripts are also given to aid readers in the implementation of the proposed formalisms.

scholarly journals Coherent Diffraction Imaging in Transmission Electron Microscopy for Atomic Resolution Quantitative Studies of the Matter

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2323
Author(s):  
Elvio Carlino ◽  
Francesco Scattarella ◽  
Liberato Caro ◽  
Cinzia Giannini ◽  
Dritan Siliqi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Phase Retrieval ◽  
Atomic Resolution ◽  
Significant Information ◽  
Heavy Atoms ◽  
Coherent Diffraction Imaging ◽  
Transmission Electron ◽  
Diffraction Imaging ◽  
Set Up

The paper focuses on the development of electron coherent diffraction imaging in transmission electron microscopy, made in the, approximately, last ten years in our collaborative research group, to study the properties of materials at atomic resolution, overcoming the limitations due to the aberrations of the electron lenses and obtaining atomic resolution images, in which the distribution of the maxima is directly related to the specimen atomic potentials projected onto the microscope image detector. Here, it is shown how augmented coherent diffraction imaging makes it possible to achieve quantitative atomic resolution maps of the specimen atomic species, even in the presence of low atomic number atoms within a crystal matrix containing heavy atoms. This aim is achieved by: (i) tailoring the experimental set-up, (ii) improving the experimental data by properly treating parasitic diffused intensities to maximize the measure of the significant information, (iii) developing efficient methods to merge the information acquired in both direct and reciprocal spaces, (iv) treating the dynamical diffused intensities to accurately measure the specimen projected potentials, (v) improving the phase retrieval algorithms to better explore the space of solutions. Finally, some of the future perspectives of coherent diffraction imaging in a transmission electron microscope are given.

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