A spectral estimation approach to contrast transfer function detection in electron microscopy

1997 ◽  
Vol 68 (4) ◽  
pp. 267-295 ◽  
Author(s):  
José-Jesús Fernández ◽  
JoséR. Sanjurjo ◽  
José-María Carazo
Keyword(s):  
Electron Microscopy ◽  
Transfer Function ◽  
Spectral Estimation ◽  
Contrast Transfer Function

scholarly journals Contrast Transfer Function-Based Exit-Wave Reconstruction and Denoising of Atomic-Resolution Transmission Electron Microscopy Images of Graphene and Cu Single Atom Substitutions by Deep Learning Framework

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1977
Author(s):  
Jongyeong Lee ◽  
Yeongdong Lee ◽  
Jaemin Kim ◽  
Zonghoon Lee
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Transfer Function ◽  
Signal To Noise Ratio ◽  
Atomic Resolution ◽  
Single Atom ◽  
Monolayer Graphene ◽  
Signal To Noise ◽  
Contrast Transfer Function ◽  
Transmission Electron

The exit wave is the state of a uniform plane incident electron wave exiting immediately after passing through a specimen and before the atomic-resolution transmission electron microscopy (ARTEM) image is modified by the aberration of the optical system and the incoherence effect of the electron. Although exit-wave reconstruction has been developed to prevent the misinterpretation of ARTEM images, there have been limitations in the use of conventional exit-wave reconstruction in ARTEM studies of the structure and dynamics of two-dimensional materials. In this study, we propose a framework that consists of the convolutional dual-decoder autoencoder to reconstruct the exit wave and denoise ARTEM images. We calculated the contrast transfer function (CTF) for real ARTEM and assigned the output of each decoder to the CTF as the amplitude and phase of the exit wave. We present exit-wave reconstruction experiments with ARTEM images of monolayer graphene and compare the findings with those of a simulated exit wave. Cu single atom substitution in monolayer graphene was, for the first time, directly identified through exit-wave reconstruction experiments. Our exit-wave reconstruction experiments show that the performance of the denoising task is improved when compared to the Wiener filter in terms of the signal-to-noise ratio, peak signal-to-noise ratio, and structural similarity index map metrics.

EM contrast transfer functions for tilted illumination imaging

1978 ◽  
Vol 36 (1) ◽  
pp. 168-169
Author(s):  
Ondrej L. Krivanek
Keyword(s):  
Electron Microscopy ◽  
Transfer Function ◽  
Transfer Functions ◽  
Theoretical Description ◽  
Phase Object ◽  
Contrast Transfer Function ◽  
Transfer Theory ◽  
Weak Phase ◽  
Theoretical Predictions ◽  
Image Position

The transfer theory of electron microscopy has now been firmly established, at least for the case of axial illumination. Tilted illumination introduces slight complications, but even so the theoretical description of the contrast transfer remains essentially quite simple. Experimentally, the existence of the main "achromatic circle" and the subsidiary circles due to plasmon scattering has been well demonstrated, but the theoretical predictions for the change in the apparent defocus and astigmatism,as determined from the image modified by tilting, has not been confirmed. This paper aims to close the gap.With coherent illumination, the contrast transfer from a weak phase object and for tilted illumination is described by including the beam tilt in the familiar axial expressions:where h(q) is the contrast transfer function (CTF), X(q) the aberration function, and the remaining symbols have their usual meaning. The derivation is algebraically lengthy, but the results can be summarised as follows.

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