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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 keV) 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

Wide-field ptychographic reconstruction of gold particles and graphitized carbon on a holey carbon support film.(a) Modulus and (b) phase of the ptychographic reconstruction. (c) Comparison with the conventional TEM image of the same area taken at 200 keV. Note the strong contrast in a, and that b exhibits phase wraps in thick areas of the object, that is, the phase passes from π to −π, forming a contour-like plot of thickness. Scale bar, 50 nm.
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f3: Wide-field ptychographic reconstruction of gold particles and graphitized carbon on a holey carbon support film.(a) Modulus and (b) phase of the ptychographic reconstruction. (c) Comparison with the conventional TEM image of the same area taken at 200 keV. Note the strong contrast in a, and that b exhibits phase wraps in thick areas of the object, that is, the phase passes from π to −π, forming a contour-like plot of thickness. Scale bar, 50 nm.

Mentions: We use the extended ptychographical iterative engine (ePIE) to re-phase the recorded diffraction data and reconstruct our images30. Figure 3 shows the reconstructed modulus and phase image of a standard TEM test specimen consisting of a holey carbon film scattered with dispersed gold particles approximately ranging from 2 to 5 nm in diameter, and also relatively thick clumps of graphitized carbon. In the conventional TEM micrograph, the bright-field image has very low contrast and, because of the transfer properties of the lens, does not express accurately the phase of the exit wave. With ptychography, we see the absolute phase induced into the transmitted electron wave over the entire field of view, a signal that is directly proportional to the product of the thickness of the specimen and its inner potential.


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)

Wide-field ptychographic reconstruction of gold particles and graphitized carbon on a holey carbon support film.(a) Modulus and (b) phase of the ptychographic reconstruction. (c) Comparison with the conventional TEM image of the same area taken at 200 keV. Note the strong contrast in a, and that b exhibits phase wraps in thick areas of the object, that is, the phase passes from π to −π, forming a contour-like plot of thickness. Scale bar, 50 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3: Wide-field ptychographic reconstruction of gold particles and graphitized carbon on a holey carbon support film.(a) Modulus and (b) phase of the ptychographic reconstruction. (c) Comparison with the conventional TEM image of the same area taken at 200 keV. Note the strong contrast in a, and that b exhibits phase wraps in thick areas of the object, that is, the phase passes from π to −π, forming a contour-like plot of thickness. Scale bar, 50 nm.
Mentions: We use the extended ptychographical iterative engine (ePIE) to re-phase the recorded diffraction data and reconstruct our images30. Figure 3 shows the reconstructed modulus and phase image of a standard TEM test specimen consisting of a holey carbon film scattered with dispersed gold particles approximately ranging from 2 to 5 nm in diameter, and also relatively thick clumps of graphitized carbon. In the conventional TEM micrograph, the bright-field image has very low contrast and, because of the transfer properties of the lens, does not express accurately the phase of the exit wave. With ptychography, we see the absolute phase induced into the transmitted electron wave over the entire field of view, a signal that is directly proportional to the product of the thickness of the specimen and its inner potential.

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 keV) 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