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Ptychographic electron microscopy using high-angle dark-field scattering for sub-nanometre resolution imaging.

Humphry MJ, Kraus B, Hurst AC, Maiden AM, Rodenburg JM - Nat Commun (2012)

Bottom Line: Diffractive imaging, in which image-forming optics are replaced by an inverse computation using scattered intensity data, could, in principle, realize wavelength-scale resolution in a transmission electron microscope.However, to date all implementations of this approach have suffered from various experimental restrictions.Here we demonstrate a form of diffractive imaging that unshackles the image formation process from the constraints of electron optics, improving resolution over that of the lens used by a factor of five and showing for the first time that it is possible to recover the complex exit wave (in modulus and phase) at atomic resolution, over an unlimited field of view, using low-energy (30 keV) electrons.

View Article: PubMed Central - PubMed

Affiliation: Phase Focus Ltd, The Electric Works, Sheffield Digital Campus, Sheffield S1 2BJ, UK.

ABSTRACT
Diffractive imaging, in which image-forming optics are replaced by an inverse computation using scattered intensity data, could, in principle, realize wavelength-scale resolution in a transmission electron microscope. However, to date all implementations of this approach have suffered from various experimental restrictions. Here we demonstrate a form of diffractive imaging that unshackles the image formation process from the constraints of electron optics, improving resolution over that of the lens used by a factor of five and showing for the first time that it is possible to recover the complex exit wave (in modulus and phase) at atomic resolution, over an unlimited field of view, using low-energy (30‚ÄČkeV) electrons. Our method, called electron ptychography, has no fundamental experimental boundaries: further development of this proof-of-principle could revolutionize sub-atomic scale transmission imaging.

No MeSH data available.


Related in: MedlinePlus

Ptychographic reconstruction of gold particles showing the atomic fringes.The full field-of-view is shown in the inset image (scale bar, 15 nm); the main image is a blow up of the region indicated by the yellow box, showing 0.236 nm atomic plane fringes (scale bar, 5 nm). The modulus and phase of the reconstructions are combined in these images, with phase represented by colour and modulus by brightness, as indicated on the colour wheel scale.
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f4: Ptychographic reconstruction of gold particles showing the atomic fringes.The full field-of-view is shown in the inset image (scale bar, 15 nm); the main image is a blow up of the region indicated by the yellow box, showing 0.236 nm atomic plane fringes (scale bar, 5 nm). The modulus and phase of the reconstructions are combined in these images, with phase represented by colour and modulus by brightness, as indicated on the colour wheel scale.

Mentions: Figure 4 shows a magnified image of several of the gold particles in a thin area of the object where the thickness issues described above do not apply. The <111> atomic planes are clearly visible in some of the particles: the spacing we measure from the image is 0.24 nm, compared with the expected value of 0.236 nm. Note that the calibration of the image magnification follows directly from the measured electron wavelength, the camera length and the dimensions of the CCD. The fringes do not occur in all the particles, and usually not over the whole of any one particle (which are known to be multiply-twinned), because for many crystalline orientations the projected planes cannot be resolved. In conventional bright-field coherent TEM imaging, the exact location of fringes associated with a particular set of Bragg planes can often be delocalized from their true real-space position. As the objective lens is defocused, periodic features are seen to cross over one another. In ptychography, the correct defocus should be guaranteed because, for a given probe shift, there is only one reconstruction focus which is consistent with the measured data, at least for the thin area of specimen examined here. In theory, the computational transfer function of the technique is perfect, so our images preserve all Fourier components, including the low frequencies that are lost in TEM.


Ptychographic electron microscopy using high-angle dark-field scattering for sub-nanometre resolution imaging.

Humphry MJ, Kraus B, Hurst AC, Maiden AM, Rodenburg JM - Nat Commun (2012)

Ptychographic reconstruction of gold particles showing the atomic fringes.The full field-of-view is shown in the inset image (scale bar, 15 nm); the main image is a blow up of the region indicated by the yellow box, showing 0.236 nm atomic plane fringes (scale bar, 5 nm). The modulus and phase of the reconstructions are combined in these images, with phase represented by colour and modulus by brightness, as indicated on the colour wheel scale.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3316878&req=5

f4: Ptychographic reconstruction of gold particles showing the atomic fringes.The full field-of-view is shown in the inset image (scale bar, 15 nm); the main image is a blow up of the region indicated by the yellow box, showing 0.236 nm atomic plane fringes (scale bar, 5 nm). The modulus and phase of the reconstructions are combined in these images, with phase represented by colour and modulus by brightness, as indicated on the colour wheel scale.
Mentions: Figure 4 shows a magnified image of several of the gold particles in a thin area of the object where the thickness issues described above do not apply. The <111> atomic planes are clearly visible in some of the particles: the spacing we measure from the image is 0.24 nm, compared with the expected value of 0.236 nm. Note that the calibration of the image magnification follows directly from the measured electron wavelength, the camera length and the dimensions of the CCD. The fringes do not occur in all the particles, and usually not over the whole of any one particle (which are known to be multiply-twinned), because for many crystalline orientations the projected planes cannot be resolved. In conventional bright-field coherent TEM imaging, the exact location of fringes associated with a particular set of Bragg planes can often be delocalized from their true real-space position. As the objective lens is defocused, periodic features are seen to cross over one another. In ptychography, the correct defocus should be guaranteed because, for a given probe shift, there is only one reconstruction focus which is consistent with the measured data, at least for the thin area of specimen examined here. In theory, the computational transfer function of the technique is perfect, so our images preserve all Fourier components, including the low frequencies that are lost in TEM.

Bottom Line: Diffractive imaging, in which image-forming optics are replaced by an inverse computation using scattered intensity data, could, in principle, realize wavelength-scale resolution in a transmission electron microscope.However, to date all implementations of this approach have suffered from various experimental restrictions.Here we demonstrate a form of diffractive imaging that unshackles the image formation process from the constraints of electron optics, improving resolution over that of the lens used by a factor of five and showing for the first time that it is possible to recover the complex exit wave (in modulus and phase) at atomic resolution, over an unlimited field of view, using low-energy (30 keV) electrons.

View Article: PubMed Central - PubMed

Affiliation: Phase Focus Ltd, The Electric Works, Sheffield Digital Campus, Sheffield S1 2BJ, UK.

ABSTRACT
Diffractive imaging, in which image-forming optics are replaced by an inverse computation using scattered intensity data, could, in principle, realize wavelength-scale resolution in a transmission electron microscope. However, to date all implementations of this approach have suffered from various experimental restrictions. Here we demonstrate a form of diffractive imaging that unshackles the image formation process from the constraints of electron optics, improving resolution over that of the lens used by a factor of five and showing for the first time that it is possible to recover the complex exit wave (in modulus and phase) at atomic resolution, over an unlimited field of view, using low-energy (30‚ÄČkeV) electrons. Our method, called electron ptychography, has no fundamental experimental boundaries: further development of this proof-of-principle could revolutionize sub-atomic scale transmission imaging.

No MeSH data available.


Related in: MedlinePlus