Der Einfluß einer streuenden Phasenplatte auf das elektronenmikroskopische Bild

1970 ◽  
Vol 25 (5) ◽  
pp. 760-765 ◽  
Author(s):  
H. G. Badde ◽  
L. Beimer
Keyword(s):  
Phase Shift ◽  
Cross Section ◽  
Focal Plane ◽  
Phase Contrast ◽  
Carbon Film ◽  
Carbon Films ◽  
Phase Shifting ◽  
Phase Plate ◽  
Different Thickness ◽  
Coherent Part

Using carbon films for phase shifting in the focal plane of the objective one has to consider the decrease of the coherent part of the electron beam. Only the unscattered part contributes to the phase contrast. After passing a 90.8 nm carbon film with a phase shift of 2 π the coherent amplitude decreases to 47%. But using a phase plate of different thickness for shifting all scattered electrons like a Zernike λ/4-plate, there will be a larger increase of contrast in images of platinum and carbon atoms than by optimal defocussing phase contrast. Calculations of phase shift and decrease of zero beam amplitude up to 1 MeV are reported. The use of Be-films with lower scattering cross section offers no large advantage.

A method of hard X-ray phase-shifting digital holography

2016 ◽  
Vol 23 (4) ◽  
pp. 1024-1029
Author(s):  
So Yeong Park ◽  
Chung Ki Hong ◽  
Jun Lim
Keyword(s):  
Phase Shift ◽  
Digital Holography ◽  
Relative Phase ◽  
Test Pattern ◽  
Fresnel Lens ◽  
Phase Shifting ◽  
New Method ◽  
Phase Plate ◽  
X Ray ◽  
Line Type

A new method of phase-shifting digital holography is demonstrated in the hard X-ray region. An in-line-type phase-shifting holography setup was installed in a 6.80 keV hard X-ray synchrotron beamline. By placing a phase plate consisting of a hole and a band at the focusing point of a Fresnel lens, the relative phase of the reference and objective beams could be successfully shifted for use with a three-step phase-shift algorithm. The system was verified by measuring the shape of a gold test pattern and a silica sphere.

Four Stage E.M. for Phase Contrast and Strioscopic Microscopy

1967 ◽  
Vol 25 ◽  
pp. 236-237 ◽  
Author(s):  
H. M. Johnson ◽  
D. F. Parsons
Keyword(s):  
Electron Microscopy ◽  
Focal Plane ◽  
Phase Contrast ◽  
Phase Plate ◽  
Biological Structures ◽  
Better Than

Phase contrast electron microscopy should allow visualization of unstained biological structures. In an attempt to achieve this, we have modified a Siemens Elmiskop la microscope, in a way similar to that described by Faget, et al. (Proc. Fifth Int. Congr. Electron Microscopy, Philad., 1962, Abstract A-7). A number of phase contrast and strioscopic arrangements can be tested. A section consisting of phase plate chamber and additional intermediate lens (I2) was added to the column between the standard intermediate lens (I1) and the projector lens (Fig. 1). I1 was set, so as to project the back focal plane of the objective to the level of the phase plate holder (Fig. 2). I2 supplied final magnifications from 1,000 x to 80,000 x. Resolution was better than 15 Å. Two stigmators were used, one in the objective back focal plane and one in the plane of the phase plate. The source consisted of either a hairpin- or point- filament to allow variable coherence of illumination.

Low-power Phase-contrast Microscopy without a Condenser

1950 ◽  
Vol s3-91 (13) ◽  
pp. 109-110
Author(s):  
D. A. KEMPSON
Keyword(s):  
Low Power ◽  
Focal Plane ◽  
Phase Contrast ◽  
Phase Plate ◽  
Phase Contrast Microscopy ◽  
Contrast Microscopy

With those low-power objectives in which a phase-plate can be placed near the back focal plane, phase-contrast microscopy can be obtained without the use of any condenser. The illuminating annulus is placed in the conjugate focus of the phaseplate.

Phase contrast and interference microscopy with the electron microscope

1971 ◽  
Vol 261 (837) ◽  
pp. 95-104 ◽  
Keyword(s):  
Electron Microscope ◽  
Phase Contrast ◽  
Carbon Film ◽  
Optical Diffraction ◽  
Interference Microscopy ◽  
Phase Plate ◽  
Bright Field ◽  
Thin Carbon ◽  
Thin Carbon Film ◽  
Electron Interference

A simple electrostatic device has been constructed which, when inserted in the optical system of an electron microscope, functions as an absorbing phase plate. Its operation depends on the central portion of a thin poorly conducting thread generating a stable potential under the influence of the electron beam and creating a particular form of electric field. An electron interference technique is employed to study the stabilizing mechanism and to develop a method for achieving the required magnitude of potential. The performance of this device is gauged by optical diffraction of electron micrographs of a thin carbon film; its application is illustrated by examining some negatively stained biological specimens. The results indicate that such an ‘electrostatic phase plate’ can provide significant improvements in contrast and signal/noise ratio over normal bright field images without loss in resolution.

scholarly journals Color Digital Holography Based on Generalized Phase-Shifting Algorithm with Monitoring Phase-Shift

Photonics ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 241
Author(s):  
Minwoo Jung ◽  
Hosung Jeon ◽  
Sungjin Lim ◽  
Joonku Hahn
Keyword(s):  
Phase Shift ◽  
Focal Plane ◽  
Digital Holography ◽  
Phase Shifter ◽  
Phase Shifting ◽  
Signal Wave ◽  
Color Filter ◽  
Object Image ◽  
Phase Shift Error ◽  
Monitoring Phase

Color digital holography (DH) has been researched in various fields such as the holographic camera and holographic microscope because it acquires a realistic color object wave by measuring both amplitude and phase. Among the methods for color DH, the phase-shifting DH has an advantage of obtaining a signal wave of objects without the autocorrelation and conjugate noises. However, this method usually requires many interferograms to obtain signals for all wavelengths. In addition, the phase-shift algorithm is sensitive to the phase-shift error caused by the instability or hysteresis of the phase shifter. In this paper, we propose a new method of color phase-shifting digital holography with monitoring the phase-shift. The color interferograms are recorded by using a focal plane array (FPA) with a Bayer color filter. In order to obtain the color signal wave from the interferograms with unexpected phase-shift values, we devise a generalized phase-shifting DH algorithm. The proposed method enables the robust measurement in the interferograms. Experimentally, we demonstrate the proposed algorithm to reconstruct the object image with negligibly small conjugate noises.

scholarly journals Investigation of hole-free phase plate performance in transmission electron microscopy under different operation conditions by experiments and simulations

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Rebecca Pretzsch ◽  
Manuel Dries ◽  
Simon Hettler ◽  
Martin Spiecker ◽  
Martin Obermair ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Phase Shift ◽  
Zero Order ◽  
Phase Shifting ◽  
Negative Phase ◽  
Phase Plate ◽  
Microscopy Imaging ◽  
Transmission Electron ◽  
Phase Plates

Abstract Hole-free phase plates (HFPPs), also known as Volta phase plates, were already demonstrated to be well suited for in-focus transmission electron microscopy imaging of organic objects. However, the underlying physical processes have not been fully understood yet. To further elucidate the imaging properties of HFPPs, phase shift measurements were carried out under different experimental conditions. Both positive and negative phase shifts occur depending on the diameter of the zero-order electron beam and the HFPP film temperature. The analysis of Thon ring patterns of an amorphous carbon test sample reveals that the phase-shifting patch can be significantly larger than the size of the zero-order beam on the HFPP film. An HFPP was used for in-focus phase contrast imaging of carbon nanotube (CNT) bundles under positive and negative phase-shifting conditions. The comparison of experimental and simulated images of CNT bundles gives detailed information on the phase shift profile, which depends on the spatial frequency in the vicinity of the zero-order beam. The shape of the phase shift profile also explains halo-like image artifacts that surround the imaged objects.

scholarly journals Phase contrast electron microscopy: development of thin-film phase plates and biological applications

2008 ◽  
Vol 363 (1500) ◽  
pp. 2153-2162 ◽  
Author(s):  
Kuniaki Nagayama ◽  
Radostin Danev
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Amorphous Carbon ◽  
Phase Contrast ◽  
Carbon Film ◽  
Objective Lens ◽  
Phase Plate ◽  
Amorphous Carbon Film ◽  
Transmission Electron ◽  
Phase Plates

Phase contrast transmission electron microscopy (TEM) based on thin-film phase plates has been developed and applied to biological systems. Currently, development is focused on two techniques that employ two different types of phase plates. The first technique uses a Zernike phase plate, which is made of a uniform amorphous carbon film that completely covers the aperture of an objective lens and can retard the phase of electron waves by π /2, except at the centre where a tiny hole is drilled. The other technique uses a Hilbert phase plate, which is made of an amorphous carbon film that is twice as thick as the Zernike phase plate, covers only half of the aperture and retards the electron wave phase by π . By combining the power of efficient phase contrast detection with the accurate preservation achieved by a cryotechnique such as vitrification, macromolecular complexes and supermolecular structures inside intact bacterial or eukaryotic cells may be visualized without staining. Phase contrast cryo-TEM has the potential to bridge the gap between cellular and molecular biology in terms of high-resolution visualization. Examples using proteins, viruses, cyanobacteria and somatic cells are provided.

Benzylamine Tartrate as an Organic Glass Substrate for Carbon Films by Evaporation

1970 ◽  
Vol 28 ◽  
pp. 484-485
Author(s):  
A. C. Faberge
Keyword(s):  
Vapor Pressure ◽  
Viscous Liquid ◽  
Glass Substrate ◽  
Room Temperature ◽  
Carbon Film ◽  
Carbon Films ◽  
Organic Glass ◽  
Spectroscopic Examination ◽  
Polymeric Substrates

Benzylamine tartrate (m.p. 63°C) seems to be a better and more convenient substrate for making carbon films than any of those previously proposed. Using it in the manner described, it is easy consistently to make batches of specimen grids as open as 200 mesh with no broken squares, and without individual handling of the grids. Benzylamine tartrate (hereafter called B.T.) is a viscous liquid when molten, which sets to a glass. Unlike polymeric substrates it does not swell before dissolving; such swelling of the substrate seems to be a principal cause of breakage of carbon film. Mass spectroscopic examination indicates a vapor pressure less than 10−9 Torr at room temperature.

Object Wave Determination by Single-Sideband Methods

1973 ◽  
Vol 31 ◽  
pp. 266-267
Author(s):  
Kenneth H. Downing ◽  
Benjamin M. Siegel
Keyword(s):  
Phase Shift ◽  
Carbon Films ◽  
Object Wave ◽  
Electron Wave ◽  
Phase Object ◽  
Heavy Atoms ◽  
Single Sideband ◽  
Thin Carbon ◽  
Additional Phase Shift ◽  
Additional Phase

Under the “weak phase object” approximation, the component of the electron wave scattered by an object is phase shifted by π/2 with respect to the unscattered component. This phase shift has been confirmed for thin carbon films by many experiments dealing with image contrast and the contrast transfer theory. There is also an additional phase shift which is a function of the atomic number of the scattering atom. This shift is negligible for light atoms such as carbon, but becomes significant for heavy atoms as used for stains for biological specimens. The light elements are imaged as phase objects, while those atoms scattering with a larger phase shift may be imaged as amplitude objects. There is a great deal of interest in determining the complete object wave, i.e., both the phase and amplitude components of the electron wave leaving the object.

Characteristics of an Electrostatic Phase Plate

1972 ◽  
Vol 30 ◽  
pp. 618-619
Author(s):  
William Krakow ◽  
Benjamin Siegel
Keyword(s):  
Phase Contrast ◽  
Objective Lens ◽  
Phase Plate ◽  
Net Charge ◽  
Phase Plates ◽  
Beam Currents ◽  
Contrast Image ◽  
Bright Phase ◽  
Additional Phase Shift ◽  
Additional Phase

Unwin has used a metallized non-conducting thread in the back focal plane of the objective lens that stops out a portion of the unscattered beam, takes on a localized positive charge and thus produces an additional phase shift to give a different transfer function of the lens. Under the particular conditions Unwin used, the phase contrast image was shifted to bright phase contrast for optimum focus.We have investigated the characteristics of this type of electrostatic phase plate, both analytically and experimentally, as functions of the magnitude of charge and defocus. Phase plates have been constructed by using Wollaston wire to mount 0.25μ diameter platinum wires across apertures ranging from 50 to 200μ diameter and vapor depositing SiO and gold on the mounted wires to give them the desired charging characteristics. The net charge was varied by adjusting only the bias on the Wehnelt shield of the gun, and hence the beam currents and effective size of the source.

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