Electronic Cone Illumination with the Conventional Transmission Electron Microscope

1977 ◽  
Vol 35 ◽  
pp. 72-73
Author(s):  
William Krakow
Keyword(s):  
Electronic Device ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Hollow Cone ◽  
Transmission Electron ◽  
Lissajous Figures ◽  
High Resolution Images ◽  
Imaging Mode ◽  
Diffraction Patterns ◽  
Transmission Microscope

An electronic device has been constructed which manipulates the primary beam in the conventional transmission microscope to illuminate a specimen under a variety of virtual condenser aperture conditions. The device uses the existing tilt coils of the microscope, and modulates the D.C. signals to both x and y tilt directions simultaneously with various waveforms to produce Lissajous figures in the back-focal plane of the objective lens. Electron diffraction patterns can be recorded which reflect the manner in which the direct beam is tilted during exposure of a micrograph. The device has been utilized mainly for the hollow cone imaging mode where the device provides a microscope transfer function without zeros in all spatial directions and has produced high resolution images which are also free from the effect of chromatic aberration. A standard second condenser aperture is employed and the width of the cone annulus is readily controlled by defocusing the second condenser lens.

Observability of Very Thick Specimen by Using Transmission Scanning Electron Microscope

1971 ◽  
Vol 29 ◽  
pp. 26-27
Author(s):  
K. Shibatomi ◽  
T. Yamanoto ◽  
H. Koike
Keyword(s):  
Electron Microscope ◽  
Image Quality ◽  
Scanning Electron Microscope ◽  
Chromatic Aberration ◽  
Image Contrast ◽  
Objective Lens ◽  
Thick Specimen ◽  
Transmission Electron ◽  
Scanning Electron

In the observation of a thick specimen by means of a transmission electron microscope, the intensity of electrons passing through the objective lens aperture is greatly reduced. So that the image is almost invisible. In addition to this fact, it have been reported that a chromatic aberration causes the deterioration of the image contrast rather than that of the resolution. The scanning electron microscope is, however, capable of electrically amplifying the signal of the decreasing intensity, and also free from a chromatic aberration so that the deterioration of the image contrast due to the aberration can be prevented. The electrical improvement of the image quality can be carried out by using the fascionating features of the SEM, that is, the amplification of a weak in-put signal forming the image and the descriminating action of the heigh level signal of the background. This paper reports some of the experimental results about the thickness dependence of the observability and quality of the image in the case of the transmission SEM.

Resolution of a Transmitted Electron Image Formed by A Scanning Electron Microscope

1970 ◽  
Vol 28 ◽  
pp. 386-387
Author(s):  
S. Takashima ◽  
H. Hashimoto ◽  
S. Kimoto
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Specimen Thickness ◽  
Probe Diameter ◽  
Transmission Electron ◽  
Electron Image ◽  
Conventional Transmission Electron Microscope ◽  
Scanning Electron

The resolution of a conventional transmission electron microscope (TEM) deteriorates as the specimen thickness increases, because chromatic aberration of the objective lens is caused by the energy loss of electrons). In the case of a scanning electron microscope (SEM), chromatic aberration does not exist as the restrictive factor for the resolution of the transmitted electron image, for the SEM has no imageforming lens. It is not sure, however, that the equal resolution to the probe diameter can be obtained in the case of a thick specimen. To study the relation between the specimen thickness and the resolution of the trans-mitted electron image obtained by the SEM, the following experiment was carried out.

Comparison of Deterministic and Linear Cosine Spatial Filtering of Transmission Electron Micrographs

1972 ◽  
Vol 30 ◽  
pp. 596-597
Author(s):  
David A. Ansley
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Spatial Filter ◽  
Operating Conditions ◽  
Objective Lens ◽  
List Type ◽  
Spatial Filters ◽  
Transmission Electron ◽  
Wide Range

The coherence of the electron flux of a transmission electron microscope (TEM) limits the direct application of deconvolution techniques which have been used successfully on unmanned spacecraft programs. The theory assumes noncoherent illumination. Deconvolution of a TEM micrograph will, therefore, in general produce spurious detail rather than improved resolution.A primary goal of our research is to study the performance of several types of linear spatial filters as a function of specimen contrast, phase, and coherence. We have, therefore, developed a one-dimensional analysis and plotting program to simulate a wide 'range of operating conditions of the TEM, including adjustment of the:(1) Specimen amplitude, phase, and separation(2) Illumination wavelength, half-angle, and tilt(3) Objective lens focal length and aperture width(4) Spherical aberration, defocus, and chromatic aberration focus shift(5) Detector gamma, additive, and multiplicative noise constants(6) Type of spatial filter: linear cosine, linear sine, or deterministic

Electron spectroscopic imaging (ESI) on multiphase polymer materials

1989 ◽  
Vol 47 ◽  
pp. 348-349
Author(s):  
H.-J. Cantow ◽  
M. Kunz ◽  
M. Möller
Keyword(s):  
Energy Loss ◽  
Melt Spinning ◽  
Chromatic Aberration ◽  
Element Distribution ◽  
Polymer Materials ◽  
Specific Energy Loss ◽  
Transmission Electron ◽  
Multicomponent Polymer ◽  
Diffraction Patterns ◽  
Image Planes

In transmission electron microscopy the natural contrast of polymers is very low. Thus the contrast has to be enhanced by staining with heavy metals. The resolution is limited by the size of the staining particles and by the fact that electrons with different energy are focused in different image planes due to the chromatic aberration of the magnetic lenses. The integration of an electron energy loss spectrometer into the optical coloumn of a transmission electron microscope offers the possibility to use monoenergetic electrons and to select electrons with a certain energy for imaging. Thus contrast and resolution are enhanced. By imaging only electrons with an element specific energy loss the element distribution in the sample can be obtained. In addition, elastic bright field images and diffraction patterns yield excellent resolution. Some applications of the method on multicomponent polymer materials are discussed.Bulk polymer samples were prepared by ultramicrotoming at room temperature or well below the glass transition temperature. Very thin films for the direct observation of the structure in semicrystalline polymers were obtained by melt-spinning. Specimens were examined with a ZEISS CEM 902 operated at 80 kV.

Ultra-high resolution SEMI-in-lens type FE-SEM, JSM-6320F, with strong magnetic-field lens with built-in secondary-electron detector

1994 ◽  
Vol 52 ◽  
pp. 484-485
Author(s):  
T. Miyokawa ◽  
H. Kazumori ◽  
S. Nakagawa ◽  
C. Nielsen
Keyword(s):  
High Resolution ◽  
Secondary Electron ◽  
Spherical Aberration ◽  
Incident Beam ◽  
Chromatic Aberration ◽  
Magnetic Flux Density ◽  
Objective Lens ◽  
Electron Detector ◽  
High Resolution Images ◽  
Working Distance

We have developed a strongly excited objective lens with a built-in secondary electron detector to provide ultra-high resolution images with high quality at low to medium accelerating voltages. The JSM-6320F is a scanning electron microscope (FE-SEM) equipped with this lens and an incident beam divergence angle control lens (ACL).The objective lens is so strongly excited as to have peak axial Magnetic flux density near the specimen surface (Fig. 1). Since the speciien is located below the objective lens, a large speciien can be accomodated. The working distance (WD) with respect to the accelerating voltage is limited due to the magnetic saturation of the lens (Fig.2). The aberrations of this lens are much smaller than those of a conventional one. The spherical aberration coefficient (Cs) is approximately 1/20 and the chromatic aberration coefficient (Cc) is 1/10. for accelerating voltages below 5kV. At the medium range of accelerating voltages (5∼15kV). Cs is 1/10 and Cc is 1/7. Typical values are Cs-1.lmm. Cc=l. 5mm at WD=2mm. and Cs=3.lmm. Cc=2.9 mm at WD=5mm. This makes the lens ideal for taking ultra-high resolution images at low to medium accelerating voltages.

Current and future aberration correctors for the improvement of resolution in electron microscopy

2009 ◽  
Vol 367 (1903) ◽  
pp. 3665-3682 ◽  
Author(s):  
M. Haider ◽  
P. Hartel ◽  
H. Müller ◽  
S. Uhlemann ◽  
J. Zach
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Low Voltage ◽  
Spherical Aberration ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Voltage Electron ◽  
System A ◽  
Transmission Electron ◽  
Correction System

The achievable resolution of a modern transmission electron microscope (TEM) is mainly limited by the inherent aberrations of the objective lens. Hence, one major goal over the past decade has been the development of aberration correctors to compensate the spherical aberration. Such a correction system is now available and it is possible to improve the resolution with this corrector. When high resolution in a TEM is required, one important parameter, the field of view, also has to be considered. In addition, especially for the large cameras now available, the compensation of off-axial aberrations is also an important task. A correction system to compensate the spherical aberration and the off-axial coma is under development. The next step to follow towards ultra-high resolution will be a correction system to compensate the chromatic aberration. With such a correction system, a new area will be opened for applications for which the chromatic aberration defines the achievable resolution, even if the spherical aberration is corrected. This is the case, for example, for low-voltage electron microscopy (EM) for the investigation of beam-sensitive materials, for dynamic EM or for in-situ EM.

Divergent-beam holography with a 200keV FE TEM

1991 ◽  
Vol 49 ◽  
pp. 678-679
Author(s):  
Xiao Zhang ◽  
David Joy
Keyword(s):  
Optical System ◽  
Photographic Film ◽  
Objective Lens ◽  
Electron Wave ◽  
Transmission Electron ◽  
High Resolution Images ◽  
Phase Data ◽  
Electron Microscopes ◽  
Complete Amplitude ◽  
Commercial Field

A hologram, first described and named by Gabor (1949), permits a medium such as photographic film, which responds only to intensity, to store the complete amplitude and phase information which characterizes an electron wavefront. The hologram is formed by allowing some fraction of a coherent electron wave which has interacted with a specimen to interact again with original incident wave so as to generate an interference pattern. If the hologram is then itself illuminated by a coherent light source and optical system which mimic the original electron-optical system then a pair of images -one real and the other virtual -can be reconstructed and viewed. Because the hologram contains both the amplitude and the phase data of the wavefront, errors and distortions in either component due to aberrations in the objective lens can be corrected by optical manipulates before the image is reconstructed. With the advent of commercial field emission transmission electron microscopes capable of generating both high resolution images and highly coherent electron beams, these holographic techniques are now available as practical tools to improve TEM performance as well as to create new modes of images (Tonomura 1987).

Analysis of electron-specimen interactions of thick biological specimens in Transmission Electron Microscopy at 200 KEV

1993 ◽  
Vol 51 ◽  
pp. 204-205
Author(s):  
Karen F. Han ◽  
Alexander J. Gubbens ◽  
Abraham J. Koster ◽  
Michael B. Braunfeld ◽  
John W. Sedat ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Mass Density ◽  
Three Dimensional ◽  
Chromatic Aberration ◽  
Background Intensity ◽  
Objective Lens ◽  
Dimensional Electron ◽  
Accurate Representation ◽  
Transmission Electron

The primary project of our laboratory is the investigation of chromatin structure by three dimensional electron microscope tomography. The goal is to understand how 30nm fibers fold into higher order chromatin structures. Three dimensional tomography involves the reconstruction of an object by combining multiple projection views of the object at different tilt angles. Due to the electronspecimen interaction and the characteristics of lens aberration in the electron microscope, however, the image is not always an accurate representation of the projected object mass density. In this abstract, we analyze the various types of electron-specimen interaction for thick biological specimens up to 0.7 microns thickness.Electron-specimen interactions include single elastic and inelastic, and multiple elastic and inelastic scattering. Of the imaging electrons, the single elastic and the plasmon electrons give rise to image intensities that can be linearly related to the projected object mass density. Multiply scattered elastic electrons contribute to an increase in background intensity. In addition, due to the chromatic aberration of the TEM’s objective lens, multiply scattered inelastic electrons cause a blurring of the image because of an effective broadening of the focus spread.

An Electron Microscope with Highly Coherent Illumination

1973 ◽  
Vol 31 ◽  
pp. 260-261
Author(s):  
R. E. Worsham ◽  
J. E. Mann ◽  
E. G. Richardson ◽  
N. F. Ziegler
Keyword(s):  
Electron Microscope ◽  
Coherence Length ◽  
Spherical Aberration ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Coherent Illumination ◽  
Illuminating Beam ◽  
Transmission Microscope

It has been shown theoretically that it is possible to correct for the defocus and the primary spherical aberration of the objective lens in a conventional transmission microscope column if the chromatic aberration can be made negligible and the transverse coherence length of the illuminating beam is about 1000A, or higher. The techniques were demonstrated with simulated micrographs. The microscope shown in the accompanying drawing and photograph was designed to test this procedure experimentally.

Imaging of Amorphous Objects by Tilted Beam Bright Field Illumination

1975 ◽  
Vol 33 ◽  
pp. 186-187
Author(s):  
W. Goldfarb ◽  
W. Krakow ◽  
D. Ast ◽  
B. Siegel
Keyword(s):  
Focal Plane ◽  
Power Spectra ◽  
Chromatic Aberration ◽  
Optic Axis ◽  
Hollow Cone ◽  
Bright Field ◽  
Transmission Electron ◽  
Single Ring ◽  
Symmetrical Pair ◽  
The One

Bright field tilted beam illumination is commonly used to demonstrate the resolution of a transmission electron microscope by forming lattice fringes.The unscattered and diffracted beams are symmetrically positioned on either side of the optic axis so that the spherical, defocus and chromatic abberations will cancel. The cancellation of chromatic aberration is particularly important. However, the balancing of aberration occurs not only for the one diffraction direction across the axis from the unscattered beam but for an entire hollow cone of scattering vectors centered on the microscope axis and passing through the unscattered beam. This hollow cone projects as a circle in the back focal plane (BFP) of the microscope with zero net aberrations for one sideband of the scattering. Because the image amplitude is squared to form the image intensity, the single ring of cancelled aberrations in the BFP corresponds to a symmetrical pair of rings in the spatial power spectra of the micrograph. These ring pairs show up strongly in the experimental diffractograms, Figures 1, 3 and 4.

Sign in / Sign up

Export Citation Format

Share Document