Phase contrast imaging using a scanning transmission electron microscope

It has already been shown 1,2,3 that the phase contrast in both the scanning transmission electron microscope and the conventional electron microscope is given by the same expression provided that the angular correspondences in Fig. 1 are maintained. This provides much useful information to the scanning microscope user as it suggests many phase contrast and interference techniques which may be used. However, the scanning microscope is a more flexible instrument, particularly with regard to the choice of the aperture angle βo and the use of a spectrometer between object and detector. In order to observe these phase effects it is necessary for the illuminating scanning spot to possess transverse coherence. This implies both that the chromatic aberration and the paraxial image of the electron source be small compared with the diffraction aberration.

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Enhanced Phase Contrast Transfer using Ptychography Combined with a Pre-Specimen Phase Plate in a Scanning Transmission Electron Microscope

Microscopy and Microanalysis ◽

10.1017/s1431927616003160 ◽

2016 ◽

Vol 22 (S3) ◽

pp. 462-463

Author(s):

Hao Yang ◽

Colin Ophus ◽

Peter Ercius ◽

Peter D. Nellist

Keyword(s):

Electron Microscope ◽

Transmission Electron Microscope ◽

Phase Contrast ◽

Scanning Transmission Electron Microscope ◽

Phase Plate ◽

Scanning Transmission Electron ◽

Transmission Electron ◽

Scanning Transmission

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A General Method for Spectrometer Design in the Scoff Approximation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100092657 ◽

1976 ◽

Vol 34 ◽

pp. 538-539

Author(s):

J. R. Fields

Keyword(s):

Electron Microscope ◽

Transmission Electron Microscope ◽

Energy Analysis ◽

Incident Beam ◽

Scanning Transmission Electron Microscope ◽

Chemical Identification ◽

Scanning Transmission Electron ◽

Transmission Electron ◽

Scanning Transmission ◽

General Method

The energy analysis of electrons scattered by a specimen in a scanning transmission electron microscope can improve contrast as well as aid in chemical identification. In so far as energy analysis is useful, one would like to be able to design a spectrometer which is tailored to his particular needs. In our own case, we require a spectrometer which will accept a parallel incident beam and which will focus the electrons in both the median and perpendicular planes. In addition, since we intend to follow the spectrometer by a detector array rather than a single energy selecting slit, we need as great a dispersion as possible. Therefore, we would like to follow our spectrometer by a magnifying lens. Consequently, the line along which electrons of varying energy are dispersed must be normal to the direction of the central ray at the spectrometer exit.

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Resolution in the Scanning Transmission Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100095522 ◽

1972 ◽

Vol 30 ◽

pp. 454-455

Author(s):

M. G. R. Thomson

Keyword(s):

Electron Microscope ◽

Transmission Electron Microscope ◽

Spherical Aberration ◽

Signal To Noise Ratio ◽

Scanning Transmission Electron Microscope ◽

Dark Field ◽

Objective Lens ◽

Scanning Transmission Electron ◽

Transmission Electron ◽

Scanning Transmission

The variation of contrast and signal to noise ratio with change in detector solid angle in the high resolution scanning transmission electron microscope was discussed in an earlier paper. In that paper the conclusions were that the most favourable conditions for the imaging of isolated single heavy atoms were, using the notation in figure 1, either bright field phase contrast with β0⋍0.5 α0, or dark field with an annular detector subtending an angle between ao and effectively π/2.The microscope is represented simply by the model illustrated in figure 1, and the objective lens is characterised by its coefficient of spherical aberration Cs. All the results for the Scanning Transmission Electron Microscope (STEM) may with care be applied to the Conventional Electron Microscope (CEM). The object atom is represented as detailed in reference 2, except that ϕ(θ) is taken to be the constant ϕ(0) to simplify the integration. This is reasonable for θ ≤ 0.1 θ0, where 60 is the screening angle.

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